Chrysler 48RE User Manual

Download

Page 1

21 - 130 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE

TABLE OF CONTENTS

page page

AUTOMATIC TRANSMISSION - 48RE

DESCRIPTION ........................132

OPERATION ..........................134

DIAGNOSIS AND TESTING

DIAGNOSIS AND TESTING - AUTOMATIC

TRANSMISSION .....................140

DIAGNOSIS AND TESTING - PRELIMINARY . 140 DIAGNOSIS AND TESTING - ROAD

TESTING ...........................140

DIAGNOSIS AND TESTING - HYDRAULIC

PRESSURE TEST ....................141

DIAGNOSIS AND TESTING - AIR TESTING

TRANSMISSION CLUTCH AND BAND

OPERATION ........................144

DIAGNOSIS AND TESTING - CONVERTER

HOUSING FLUID LEAK ................144

DIAGNOSIS AND TESTING - DIAGNOSIS

CHARTS ...........................145

STANDARD PROCEDURE - ALUMINUM

THREAD REPAIR .....................158

REMOVAL ............................158

DISASSEMBLY ........................160

CLEANING ...........................166

INSPECTION .........................166

ASSEMBLY ...........................166

INSTALLATION ........................174

SCHEMATICS AND DIAGRAMS

HYDRAULIC SCHEMATICS .............176

SPECIFICATIONS

TRANSMISSION .....................189

SPECIAL TOOLS

RE TRANSMISSION ..................191

ACCUMULATOR

DESCRIPTION ........................193

OPERATION ..........................193

INSPECTION .........................194

BANDS

DESCRIPTION ........................194

OPERATION ..........................194

ADJUSTMENTS

ADJUSTMENT - BANDS ...............195

BRAKE TRANSMISSION SHIFT INTERLOCK

SYSTEM

DESCRIPTION ........................196

OPERATION ..........................196

DIAGNOSIS AND TESTING - BRAKE

TRANSMISSION SHIFT INTERLOCK ......196

ADJUSTMENTS - BRAKE TRANSMISSION

SHIFT INTERLOCK ...................196

ELECTRONIC GOVERNOR

DESCRIPTION ........................197

OPERATION ..........................198

REMOVAL ............................199

INSTALLATION ........................200

EXTENSION HOUSING SEAL

REMOVAL ............................201

INSTALLATION ........................201

FLUID AND FILTER

DIAGNOSIS AND TESTING

DIAGNOSIS AND TESTING - EFFECTS OF

INCORRECT FLUID LEVEL .............201

DIAGNOSIS AND TESTING - CAUSES OF

BURNT FLUID .......................201

DIAGNOSIS AND TESTING - FLUID

CONTAMINATION ....................202

STANDARD PROCEDURE

STANDARD PROCEDURE - FLUID LEVEL

CHECK ............................202

STANDARD PROCEDURE - FLUID AND

FILTER REPLACEMENT ...............203

STANDARD PROCEDURE - TRANSMISSION

FILL ...............................204

FRONT CLUTCH

DESCRIPTION ........................205

OPERATION ..........................205

DISASSEMBLY ........................205

INSPECTION .........................206

ASSEMBLY ...........................207

FRONT SERVO

DESCRIPTION ........................208

OPERATION ..........................208

DISASSEMBLY ........................209

CLEANING ...........................209

INSPECTION .........................209

ASSEMBLY ...........................209

GEARSHIFT CABLE

DIAGNOSIS AND TESTING - GEARSHIFT

CABLE .............................210

REMOVAL ............................210

INSTALLATION ........................211

ADJUSTMENTS

GEARSHIFT CABLE ..................212

OIL PUMP

DESCRIPTION ........................213

OPERATION ..........................213

DISASSEMBLY ........................214

CLEANING ...........................214

INSPECTION .........................214

ASSEMBLY ...........................214

Page 2

DR AUTOMATIC TRANSMISSION - 48RE 21 - 131

OUTPUT SHAFT FRONT BEARING

REMOVAL ............................216

INSTALLATION ........................216

OUTPUT SHAFT REAR BEARING

REMOVAL ............................216

INSTALLATION ........................217

OVERDRIVE CLUTCH

DESCRIPTION ........................217

OPERATION ..........................217

OVERDRIVE UNIT

REMOVAL ............................218

DISASSEMBLY ........................218

CLEANING ...........................225

INSPECTION .........................225

ASSEMBLY ...........................226

INSTALLATION ........................235

OVERRUNNING CLUTCH CAM/OVERDRIVE

PISTON RETAINER

DESCRIPTION ........................236

OPERATION ..........................236

DISASSEMBLY ........................236

CLEANING ...........................236

INSPECTION .........................237

ASSEMBLY ...........................237

PISTONS

DESCRIPTION ........................239

OPERATION ..........................239

PLANETARY GEARTRAIN/OUTPUT SHAFT

DESCRIPTION ........................241

OPERATION ..........................241

DISASSEMBLY ........................242

INSPECTION .........................243

ASSEMBLY ...........................244

REAR CLUTCH

DESCRIPTION ........................247

OPERATION ..........................248

DISASSEMBLY ........................248

CLEANING ...........................248

INSPECTION .........................248

ASSEMBLY ...........................249

REAR SERVO

DESCRIPTION ........................251

OPERATION ..........................251

DISASSEMBLY ........................251

CLEANING ...........................251

ASSEMBLY ...........................251

SHIFT MECHANISM

DESCRIPTION ........................252

OPERATION ..........................252

SOLENOID

DESCRIPTION ........................252

OPERATION ..........................252

SPEED SENSOR

DESCRIPTION ........................253

OPERATION ..........................253

THROTTLE VALVE CABLE

DESCRIPTION ........................253

ADJUSTMENTS - THROTTLE VALVE CABLE . 254

TORQUE CONVERTER

DESCRIPTION ........................255

OPERATION ..........................259

REMOVAL ............................260

INSTALLATION ........................260

TORQUE CONVERTER DRAINBACK VALVE

DESCRIPTION ........................261

OPERATION ..........................261

STANDARD PROCEDURE - TORQUE

CONVERTER DRAINBACK VALVE ........261

TOW/HAUL OVERDRIVE SWITCH

DESCRIPTION ........................261

OPERATION ..........................262

DIAGNOSIS AND TESTING - OVERDRIVE

ELECTRICAL CONTROLS ..............262

REMOVAL ............................262

INSTALLATION ........................262

TRANSMISSION RANGE SENSOR

DESCRIPTION ........................263

OPERATION ..........................263

DIAGNOSIS AND TESTING - TRANSMISSION

RANGE SENSOR (TRS) ................264

REMOVAL ............................265

INSTALLATION ........................266

TRANSMISSION TEMPERATURE SENSOR

DESCRIPTION ........................267

OPERATION ..........................267

VALVE BODY

DESCRIPTION ........................267

OPERATION ..........................272

REMOVAL ............................286

DISASSEMBLY ........................287

CLEANING ...........................298

INSPECTION .........................298

ASSEMBLY ...........................299

INSTALLATION ........................309

ADJUSTMENTS - VALVE BODY ...........310

Page 3

21 - 132 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION 48RE

DESCRIPTION

The 48RE (Fig. 1) is a four speed fully automatic transmissions with an electronic governor. The 48RE is equipped with a lock-up clutch in the torque converter. First through third gear ranges are provided by the clutches, bands, overrunning clutch, and planetary gear sets in the transmission. Fourth gear range is provided by the overdrive unit that contains an overdrive clutch, direct clutch, planetary gear set, and overrunning clutch.

The transmission contains a front, rear, and direct clutch which function as the input driving components. It also contains the kickdown (front) and the

low/reverse (rear) bands which, along with the overrunning clutch and overdrive clutch, serve as the holding components. The driving and holding components combine to select the necessary planetary gear components, in the front, rear, or overdrive planetary gear set, transfer the engine power from the input shaft through to the output shaft.

The valve body is mounted to the lower side of the transmission and contains the valves to control pressure regulation, fluid flow control, and clutch/band application. The oil pump is mounted at the front of the transmission and is driven by the torque converter hub. The pump supplies the oil pressure necessary for clutch/band actuation and transmission lubrication.

Page 4

DR AUTOMATIC TRANSMISSION - 48RE 21 - 133

AUTOMATIC TRANSMISSION - 48RE (Continued)

Fig. 1 48RE Transmission

Page 5

21 - 134 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

1 - TORQUE CONVERTER 10 - OVERDRIVE CLUTCH 2 - INPUT SHAFT 11 - DIRECT CLUTCH 3 - OIL PUMP 12 - PLANETARY GEAR 4 - FRONT BAND 13 - INTERMEDIATE SHAFT 5 - FRONT CLUTCH 14 - OVERDRIVE OVERRUNNING CLUTCH 6 - REAR CLUTCH 15 - DIRECT CLUTCH SPRING 7 - PLANETARIES 16 - OVERDRIVE PISTON RETAINER 8 - REAR BAND 17 - OIL PAN 9 - OVERRUNNING CLUTCH 18 - VALVE BODY

IDENTIFICATION

Transmission identification numbers are stamped on the left side of the case just above the oil pan gasket surface (Fig. 2). Refer to this information when ordering replacement parts.

Fig. 2 Transmission Part Number And Serial

Number Location

1 - PART NUMBER 2 - BUILD DATE 3 - SERIAL NUMBER

GEAR RATIOS

The 48RE gear ratios are:

1st .................................2.45:1

2nd ................................1.45:1

3rd ................................1.00:1

4th .................................0.69:1

Rev. ................................2.20:1

OPERATION

The application of each driving or holding component is controlled by the valve body based upon the manual lever position, throttle pressure, and governor pressure. The governor pressure is a variable pressure input to the valve body and is one of the signals that a shift is necessary. First through fourth gear are obtained by selectively applying and releasing the different clutches and bands. Engine power is thereby routed to the various planetary gear assemblies which combine with the overrunning clutch assemblies to generate the different gear ratios. The torque converter clutch is hydraulically applied and is released when fluid is vented from the hydraulic circuit by the torque converter control (TCC) solenoid on the valve body. The torque converter clutch is controlled by the Powertrain Control Module (PCM). The torque converter clutch engages in fourth gear, and in third gear under various conditions, such as when the O/D switch is OFF, when the vehicle is cruising on a level surface after the vehicle has warmed up. The torque converter clutch can also be engaged in the MANUAL SECOND gear position if high transmission temperatures are sensed by the PCM. The torque converter clutch will disengage momentarily when an increase in engine load is sensed by the PCM, such as when the vehicle begins to go uphill or the throttle pressure is increased. The torque converter clutch feature increases fuel economy and reduces the transmission fluid temperature.

Since the overdrive clutch is applied in fourth gear only and the direct clutch is applied in all ranges except fourth gear, the transmission operation for park, neutral, and first through third gear will be described first. Once these powerflows are described, the third to fourth shift sequence will be described.

Page 6

DR AUTOMATIC TRANSMISSION - 48RE 21 - 135

AUTOMATIC TRANSMISSION - 48RE (Continued)

PARK POWERFLOW

As the engine is running and the crankshaft is rotating, the flexplate and torque converter, which are also bolted to it, are all rotating in a clockwise direction as viewed from the front of the engine. The notched hub of the torque converter is connected to the oil pump’s internal gear, supplying the transmission with oil pressure. As the converter turns, it turns the input shaft in a clockwise direction. As the input shaft is rotating, the front clutch hub-rear clutch retainer and all their associated parts are also rotating, all being directly connected to the input shaft. The power flow from the engine through the front clutch hub and rear clutch retainer stops at the rear clutch retainer. Therefore, no power flow to the output shaft occurs because no clutches are applied. The only mechanism in use at this time is the parking sprag (Fig. 3), which locks the parking gear on the output shaft to the transmission case.

NEUTRAL POWERFLOW

With the gear selector in the NEUTRAL position (Fig. 4), the power flow of the transmission is essentially the same as in the park position. The only operational difference is that the parking sprag has been disengaged, unlocking the output shaft from the transmission case and allowing it to move freely.

Fig. 3 Park Powerflow

1 - PAWL ENGAGED FOR PARK 2 - PARK SPRAG 3 - OUTPUT SHAFT

Fig. 4 Neutral Powerflow

1 - PAWL DISENGAGED FOR NEUTRAL 2 - PARK SPRAG 3 - OUTPUT SHAFT 4 - CAM 5-PAWL

Page 7

21 - 136 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

REVERSE POWERFLOW

When the gear selector is moved into the REVERSE position (Fig. 5), the front clutch and the rear band are applied. With the application of the front clutch, engine torque is applied to the sun gear, turning it in a clockwise direction. The clockwise rotation of the sun gear causes the rear planet pinions to rotate against engine rotation in a counterclockwise direction. The rear band is holding the low reverse drum, which is splined to the rear carrier. Since the rear carrier is being held, the torque from

the planet pinions is transferred to the rear annulus gear, which is splined to the output shaft. The output shaft in turn rotates with the annulus gear in a counterclockwise direction giving a reverse gear output. The entire transmission of torque is applied to the rear planetary gearset only. Although there is torque input to the front gearset through the sun gear, no other member of the gearset is being held. During the entire reverse stage of operation, the front planetary gears are in an idling condition.

1 - FRONT CLUTCH ENGAGED 5 - OUTPUT SHAFT 2 - OUTPUT SHAFT 6 - INPUT SHAFT 3 - LOW/REVERSE BAND APPLIED 7 - FRONT CLUTCH ENGAGED 4 - INPUT SHAFT 8 - LOW/REVERSE BAND APPLIED

Fig. 5 Reverse Powerflow

Page 8

DR AUTOMATIC TRANSMISSION - 48RE 21 - 137

AUTOMATIC TRANSMISSION - 48RE (Continued)

FIRST GEAR POWERFLOW

When the gearshift lever is moved into the DRIVE position the transmission goes into first gear (Fig. 6). As soon as the transmission is shifted from PARK or NEUTRAL to DRIVE, the rear clutch applies, applying the rear clutch pack to the front annulus gear. Engine torque is now applied to the front annulus gear turning it in a clockwise direction. With the front annulus gear turning in a clockwise direction, it causes the front planets to turn in a clockwise direction. The rotation of the front planets cause the sun to revolve in a counterclockwise direction. The sun gear now transfers its counterclockwise rotation to the rear planets which rotate back in a clockwise

direction. With the rear annulus gear stationary, the rear planet rotation on the annulus gear causes the rear planet carrier to revolve in a counterclockwise direction. The rear planet carrier is splined into the low-reverse drum, and the low reverse drum is splined to the inner race of the over-running clutch. With the over-running clutch locked, the planet carrier is held, and the resulting torque provided by the planet pinions is transferred to the rear annulus gear. The rear annulus gear is splined to the output shaft and rotated along with it (clockwise) in an underdrive gear reduction mode.

1 - OUTPUT SHAFT 5 - OVER-RUNNING CLUTCH HOLDING 2 - OVER-RUNNING CLUTCH HOLDING 6 - INPUT SHAFT 3 - REAR CLUTCH APPLIED 7 - REAR CLUTCH APPLIED 4 - OUTPUT SHAFT 8 - INPUT SHAFT

Fig. 6 First Gear Powerflow

Page 9

21 - 138 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

SECOND GEAR POWERFLOW

In DRIVE-SECOND (Fig. 7), the same elements are applied as in MANUAL-SECOND. Therefore, the power flow will be the same, and both gears will be discussed as one in the same. In DRIVE-SECOND, the transmission has proceeded from first gear to its shift point, and is shifting from first gear to second. The second gear shift is obtained by keeping the rear clutch applied and applying the front (kickdown) band. The front band holds the front clutch retainer that is locked to the sun gear driving shell. With the rear clutch still applied, the input is still on the front annulus gear turning it clockwise at engine speed.

Now that the front band is holding the sun gear stationary, the annulus rotation causes the front planets to rotate in a clockwise direction. The front carrier is then also made to rotate in a clockwise direction but at a reduced speed. This will transmit the torque to the output shaft, which is directly connected to the front planet carrier. The rear planetary annulus gear will also be turning because it is directly splined to the output shaft. All power flow has occurred in the front planetary gear set during the drive-second stage of operation, and now the over-running clutch, in the rear of the transmission, is disengaged and freewheeling on its hub.

1 - KICKDOWN BAND APPLIED 6 - INPUT SHAFT 2 - OUTPUT SHAFT 7 - REAR CLUTCH APPLIED 3 - REAR CLUTCH ENGAGED 8 - KICKDOWN BAND APPLIED 4 - OUTPUT SHAFT 9 - INPUT SHAFT 5 - OVER-RUNNING CLUTCH FREE-WHEELING

Fig. 7 Second Gear Powerflow

Page 10

DR AUTOMATIC TRANSMISSION - 48RE 21 - 139

AUTOMATIC TRANSMISSION - 48RE (Continued)

DIRECT DRIVE POWERFLOW

The vehicle has accelerated and reached the shift point for the 2-3 upshift into direct drive (Fig. 8). When the shift takes place, the front band is released, and the front clutch is applied. The rear clutch stays applied as it has been in all the forward gears. With the front clutch now applied, engine torque is now on the front clutch retainer, which is locked to the sun gear driving shell. This means that the sun gear is now turning in engine rotation (clockwise) and at engine speed. The rear clutch is still applied so engine torque is also still on the front annulus gear. If two members of the same planetary set are driven, direct drive results. Therefore, when two members are rotating at the same speed and in the same direction, it is the same as being locked up. The rear planetary set is also locked up, given the sun gear is still the input, and the rear annulus gear must turn with the output shaft. Both gears are turning in the same direction and at the same speed. The front and rear planet pinions do not turn at all in direct drive. The only rotation is the input from the engine to the connected parts, which are acting as one common unit, to the output shaft.

FOURTH GEAR POWERFLOW

Fourth gear overdrive range is electronically controlled and hydraulically activated. Various sensor inputs are supplied to the powertrain control module to operate the overdrive solenoid on the valve body. The solenoid contains a check ball that opens and closes a vent port in the 3-4 shift valve feed passage. The overdrive solenoid (and check ball) are not energized in first, second, third, or reverse gear. The vent port remains open, diverting line pressure from the 2-3 shift valve away from the 3-4 shift valve. The Tow/Haul control switch must be in the ON position to transmit overdrive status to the PCM. A 3-4 upshift occurs only when the overdrive solenoid is energized by the PCM. The PCM energizes the overdrive solenoid during the 3-4 upshift. This causes the solenoid check ball to close the vent port allowing line pressure from the 2-3 shift valve to act directly on the 3-4 upshift valve. Line pressure on the 3-4 shift valve overcomes valve spring pressure moving the valve to the upshift position. This action exposes the feed passages to the 3-4 timing valve, 3-4 quick fill valve, 3-4 accumulator, and ultimately to the overdrive piston. Line pressure through the timing

1 - FRONT CLUTCH APPLIED 6 - INPUT SHAFT 2 - OVER-RUNNING CLUTCH FREE-WHEELING 7 - OVER-RUNNING CLUTCH FREE-WHEELING 3 - OUTPUT SHAFT 8 - REAR CLUTCH APPLIED 4 - REAR CLUTCH APPLIED 9 - FRONT CLUTCH APPLIED 5 - OUTPUT SHAFT 10 - INPUT SHAFT

Fig. 8 Direct Drive Powerflow

Page 11

21 - 140 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

valve moves the overdrive piston into contact with the overdrive clutch. The direct clutch is disengaged before the overdrive clutch is engaged. The boost valve provides increased fluid apply pressure to the overdrive clutch during 3-4 upshifts, and when accelerating in fourth gear. The 3-4 accumulator cushions overdrive clutch engagement to smooth 3-4 upshifts. The accumulator is charged at the same time as apply pressure acts against the overdrive piston.

DIAGNOSIS AND TESTING

DIAGNOSIS AND TESTING - AUTOMATIC TRANSMISSION

Automatic transmission problems can be a result of poor engine performance, incorrect fluid level, incorrect linkage or cable adjustment, band or hydraulic control pressure adjustments, hydraulic system malfunctions or electrical/mechanical component malfunctions. Begin diagnosis by checking the easily accessible items such as: fluid level and condition, linkage adjustments and electrical connections. A road test will determine if further diagnosis is necessary.

DIAGNOSIS AND TESTING - PRELIMINARY

Two basic procedures are required. One procedure for vehicles that are drivable and an alternate procedure for disabled vehicles (will not back up or move forward).

VEHICLE IS DRIVEABLE

(1) Check for transmission fault codes using DRBt scan tool.

(2) Check fluid level and condition.

(3) Adjust throttle and gearshift linkage if complaint was based on delayed, erratic, or harsh shifts.

(4) Road test and note how transmission upshifts, downshifts, and engages.

(5) Perform hydraulic pressure test if shift problems were noted during road test.

(6) Perform air-pressure test to check clutch-band operation.

VEHICLE IS DISABLED

(1) Check fluid level and condition. (2) Check for broken or disconnected gearshift or

throttle linkage.

(3) Check for cracked, leaking cooler lines, or loose

or missing pressure-port plugs.

(4) Raise and support vehicle on safety stands, start engine, shift transmission into gear, and note following:

(a) If propeller shaft turns but wheels do not,

problem is with differential or axle shafts.

(b) If propeller shaft does not turn and transmission is noisy, stop engine. Remove oil pan, and check for debris. If pan is clear, remove transmission and check for damaged drive plate, converter, oil pump, or input shaft.

(c) If propeller shaft does not turn and transmission is not noisy, perform hydraulic-pressure test to determine if problem is hydraulic or mechanical.

DIAGNOSIS AND TESTING - ROAD TESTING

Before road testing, be sure the fluid level and con-

trol cable adjustments have been checked and adjusted if necessary. Verify that diagnostic trouble codes have been resolved.

Observe engine performance during the road test.

A poorly tuned engine will not allow accurate analysis of transmission operation.

Operate the transmission in all gear ranges. Check

for shift variations and engine flare which indicates slippage. Note if shifts are harsh, spongy, delayed, early, or if part throttle downshifts are sensitive.

Slippage indicated by engine flare, usually means

clutch, band or overrunning clutch problems. If the condition is advanced, an overhaul will be necessary to restore normal operation.

A slipping clutch or band can often be determined

by comparing which internal units are applied in the various gear ranges. The Clutch and Band Application chart provides a basis for analyzing road test results.

Page 12

DR AUTOMATIC TRANSMISSION - 48RE 21 - 141

AUTOMATIC TRANSMISSION - 48RE (Continued)

CLUTCH AND BAND APPLICATION CHART

SHIFT

LEVER

POSITION

Reverse X X X

Drive -

First

Drive -

Second

Drive -

Third

Drive Fourth

Manual Second

Manual

First

Note that the rear clutch is applied in all forward ranges (D, 2, 1). The transmission overrunning clutch is applied in first gear (D, 2 and 1 ranges) only. The rear band is applied in 1 and R range only.

Note that the overdrive clutch is applied only in fourth gear and the overdrive direct clutch and overrunning clutch are applied in all ranges except fourth gear.

For example: If slippage occurs in first gear in D and 2 range but not in 1 range, the transmission overrunning clutch is faulty. Similarly, if slippage occurs in any two forward gears, the rear clutch is slipping.

Applying the same method of analysis, note that the front and rear clutches are applied simultaneously only in D range third and fourth gear. If the transmission slips in third gear, either the front clutch or the rear clutch is slipping.

If the transmission slips in fourth gear but not in third gear, the overdrive clutch is slipping. By selecting another gear which does not use these clutches, the slipping unit can be determined. For example, if the transmission also slips in Reverse, the front clutch is slipping. If the transmission does not slip in Reverse, the rear clutch is slipping.

If slippage occurs during the 3-4 shift or only in fourth gear, the overdrive clutch is slipping. Similarly, if the direct clutch were to fail, the transmission would lose both reverse gear and overrun braking in 2 position (manual second gear).

If the transmission will not shift to fourth gear, the control switch, overdrive solenoid or related wiring may also be the problem cause.

FRONT

CLUTCH

TRANSMISSION CLUTCHES AND BANDS OVERDRIVE CLUTCHES

FRONT

BAND

XX XX

XX X

XX XX

REAR

CLUTCH

XXXX

XXX XX

REAR BAND

a slipping unit and check operation. Proper use of the Clutch and Band Application Chart is the key.

slipping unit, the actual cause of a malfunction usually cannot be determined until hydraulic and air pressure tests are performed. Practically any condition can be caused by leaking hydraulic circuits or sticking valves.

in D range first gear, do not disassemble the transmission. Perform the hydraulic and air pressure tests to help determine the probable cause.

OVER-

RUNNING

CLUTCH

This process of elimination can be used to identify

Although road test analysis will help determine the

Unless a malfunction is obvious, such as no drive

OVERDRIVE

CLUTCH

DIAGNOSIS AND TESTING - HYDRAULIC PRESSURE TEST

Hydraulic test pressures range from a low of one psi (6.895 kPa) governor pressure, to 300 psi (2068 kPa) at the rear servo pressure port in reverse.

An accurate tachometer and pressure test gauges are required. Test Gauge C-3292 has a 100 psi range and is used at the accumulator, governor, and front servo ports. Test Gauge C-3293-SP has a 300 psi range and is used at the rear servo and overdrive ports where pressures exceed 100 psi.

Pressure Test Port Locations

Test ports are located at both sides of the transmission case (Fig. 9).

Line pressure is checked at the accumulator port on the right side of the case. The front servo pressure port is at the right side of the case just behind the filler tube opening.

DIRECT

CLUTCH

OVER-

RUNNING

CLUTCH

Page 13

21 - 142 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

The rear servo and governor pressure ports are at the right rear of the transmission case. The overdrive clutch pressure port is at the left rear of the case.

Fig. 9 Pressure Test Port Locations

1 - REAR SERVO TEST PORT 2 - GOVERNOR TEST PORT 3 - ACCUMULATOR TEST PORT 4 - FRONT SERVO TEST PORT 5 - OVERDRIVE CLUTCH TEST PORT

Test One - Transmission In Manual Low

This test checks pump output, pressure regulation, and condition of the rear clutch and servo circuit. Both test gauges are required for this test.

(1) Connect tachometer to engine. Position tachometer so it can be observed from driver seat if helper will be operating engine. Raise vehicle on hoist that will allow rear wheels to rotate freely.

(2) Connect 100 psi Gauge C-3292 to accumulator port. Then connect 300 psi Gauge C-3293-SP to rear servo port.

(3) Disconnect throttle and gearshift cables from levers on transmission valve body manual shaft.

(4) Have helper start and run engine at 1000 rpm.

(5) Move transmission shift lever fully forward into 1 range.

(6) Gradually move transmission throttle lever from full forward to full rearward position and note pressures on both gauges:

• Line pressure at accumulator port should be 54-60 psi (372-414 kPa) with throttle lever forward and gradually increase to 90-96 psi (621-662 kPa) as throttle lever is moved rearward.

• Rear servo pressure should be same as line pressure within 3 psi (20.68 kPa).

Test Two - Transmission In 2 Range

This test checks pump output, line pressure and pressure regulation. Use 100 psi Test Gauge C-3292 for this test.

(1) Leave vehicle in place on hoist and leave Test Gauge C-3292 connected to accumulator port.

(2) Have helper start and run engine at 1000 rpm.

(3) Move transmission shift lever one detent rearward from full forward position. This is 2 range.

(4) Move transmission throttle lever from full forward to full rearward position and read pressure on gauge.

(5) Line pressure should be 54-60 psi (372-414 kPa) with throttle lever forward and gradually increase to 90-96 psi (621-662 kPa) as lever is moved rearward.

Test Three - Transmission In D Range Third Gear

This test checks pressure regulation and condition of the clutch circuits. Both test gauges are required for this test.

(1) Turn OD switch off.

(2) Leave vehicle on hoist and leave Gauge C-3292 in place at accumulator port.

(3) Move Gauge C-3293-SP over to front servo port for this test.

(4) Have helper start and run engine at 1600 rpm for this test.

(5) Move transmission shift lever two detents rearward from full forward position. This is D range.

(6) Read pressures on both gauges as transmission throttle lever is gradually moved from full forward to full rearward position:

• Line pressure at accumulator in D range third gear, should be 54-60 psi (372-414 kPa) with throttle lever forward and increase as lever is moved rearward.

• Front servo pressure in D range third gear, should be within 3 psi (21 kPa) of line pressure up to kickdown point.

Test Four - Transmission In Reverse

This test checks pump output, pressure regulation and the front clutch and rear servo circuits. Use 300 psi Test Gauge C-3293-SP for this test.

(1) Leave vehicle on hoist and leave gauge C-3292 in place at accumulator port.

(2) Move 300 psi Gauge C-3293-SP back to rear servo port.

Page 14

DR AUTOMATIC TRANSMISSION - 48RE 21 - 143

AUTOMATIC TRANSMISSION - 48RE (Continued)

(3) Have helper start and run engine at 1600 rpm

for test.

Move transmission shift lever four detents rear-

(4)

ward from full forward position. This is Reverse range.

(5) Move transmission throttle lever fully forward then fully rearward and note reading at Gauge C-3293-SP.

(6) Pressure should be 145 - 175 psi (1000-1207 kPa) with throttle lever forward and increase to 230 280 psi (1586-1931 kPa) as lever is gradually moved rearward.

Test Five - Governor Pressure

This test checks governor operation by measuring governor pressure response to changes in vehicle speed. It is usually not necessary to check governor operation unless shift speeds are incorrect or if the transmission will not downshift. The test should be performed on the road or on a hoist that will allow the rear wheels to rotate freely.

(1) Move 100 psi Test Gauge C-3292 to governor pressure port.

(2) Move transmission shift lever two detents rearward from full forward position. This is D range.

(3) Have helper start and run engine at curb idle speed. Then firmly apply service brakes so wheels will not rotate.

(4) Note governor pressure:

Governor pressure should be no more than 20.6

•

kPa (3 psi) at curb idle speed and wheels not rotating.

• If pressure exceeds 20.6 kPa (3 psi), a fault

exists in governor pressure control system.

(5) Release brakes, slowly increase engine speed, and observe speedometer and pressure test gauge (do not exceed 30 mph on speedometer). Governor pressure should increase in proportion to vehicle speed. Or approximately 6.89 kPa (1 psi) for every 1 mph.

(6) Governor pressure rise should be smooth and drop back to no more than 20.6 kPa (3 psi), after engine returns to curb idle and brakes are applied to prevent wheels from rotating.

Compare results of pressure test with analysis

(7) chart.

Test Six - Transmission In Overdrive Fourth Gear

This test checks line pressure at the overdrive clutch in fourth gear range. Use 300 psi Test Gauge C-3293-SP for this test. The test should be performed on the road or on a chassis dyno.

Remove tachometer; it is not needed for this test.

(1)

(2) Move 300 psi Gauge to overdrive clutch pressure test port. Then remove other gauge and reinstall test port plug.

(3) Lower vehicle.

(4) Turn OD switch on.

(5) Secure test gauge so it can be viewed from

drivers seat.

(6) Start engine and shift into D range. (7) Increase vehicle speed gradually until 3-4 shift

occurs and note gauge pressure.

(8) Pressure should be 524-565 kPa (76-82 psi) with closed throttle and increase to 690-896 kPa (100-130 psi) at 1/2 to 3/4 throttle. Note that pressure can increase to around 965 kPa (140 psi) at full throttle.

(9) Return to shop or move vehicle off chassis dyno.

PRESSURE TEST ANALYSIS CHART

TEST CONDITION INDICATION

Line pressure OK during any one test

Line pressure OK in R but low in D, 2, 1

Pressure low in D Fourth Gear Range

Pressure OK in 1, 2 but low in D3 and R

Pressure OK in 2 but low in R and 1

Front servo pressure in 2 Leakage in servo; broken

Pressure low in all positions

Governor pressure too high at idle speed

Governor pressure low at all mph figures

Lubrication pressure low at all throttle positions

Line pressure high Output shaft plugged,

Line pressure low Sticky regulator valve,

Pump and regulator valve OK

Leakage in rear clutch area (seal rings, clutch seals)

Overdrive clutch piston seal, or check ball problem

Leakage in front clutch area

Leakage in rear servo

servo ring or cracked servo piston

Clogged filter, stuck regulator valve, worn or faulty pump, low oil level

Governor pressure solenoid valve system fault. Refer to diagnostic book.

Faulty governor pressure solenoid, transmission control module, or governor pressure sensor

Clogged fluid cooler or lines, seal rings leaking, worn pump bushings, pump, clutch retainer, or clogged filter.

sticky regulator valve

clogged filter, worn pump

Page 15

21 - 144 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

DIAGNOSIS AND TESTING - AIR TESTING TRANSMISSION CLUTCH AND BAND OPERATION

Air-pressure testing can be used to check transmission front/rear clutch and band operation. The test can be conducted with the transmission either in the vehicle or on the work bench, as a final check, after overhaul.

Air-pressure testing requires that the oil pan and valve body be removed from the transmission. The servo and clutch apply passages are shown (Fig. 10).

Fig. 10 Air Pressure Test Passages

1 - LINE PRESSURE TO ACCUMULATOR 2 - REAR SERVO APPLY 3 - FRONT SERVO APPLY 4 - FRONT SERVO RELEASE 5 - PUMP SUCTION 6 - PUMP PRESSURE 7 - FRONT CLUTCH APPLY 8 - REAR CLUTCH APPLY 9 - TO TORQUE CONVERTOR 10 - TO COOLER 11 - FROM TORQUE CONVERTER

Front Clutch Air Test

Place one or two fingers on the clutch housing and apply air pressure through front clutch apply passage. Piston movement can be felt and a soft thump heard as the clutch applies.

Rear Clutch Air Test

Place one or two fingers on the clutch housing and apply air pressure through rear clutch apply passage. Piston movement can be felt and a soft thump heard as the clutch applies.

Front Servo Air Test

Apply air pressure to the front servo apply passage. The servo rod should extend and cause the band to tighten around the drum. Spring pressure should release the servo when air pressure is removed.

Rear Servo Air Test

Apply air pressure to the rear servo apply passage. The servo rod should extend and cause the band to tighten around the drum. Spring pressure should release the servo when air pressure is removed.

DIAGNOSIS AND TESTING - CONVERTER HOUSING FLUID LEAK

When diagnosing converter housing fluid leaks, two items must be established before repair.

(1) Verify that a leak condition actually exists.

(2) Determined the true source of the leak.

Some suspected converter housing fluid leaks may not be leaks at all. They may only be the result of residual fluid in the converter housing, or excess fluid spilled during factory fill or fill after repair. Converter housing leaks have several potential sources. Through careful observation, a leak source can be identified before removing the transmission for repair. Pump seal leaks tend to move along the drive hub and onto the rear of the converter. Pump body leaks follow the same path as a seal leak (Fig.

11). Pump vent or pump attaching bolt leaks are generally deposited on the inside of the converter housing and not on the converter itself (Fig. 11). Pump o-ring or gasket leaks usually travel down the inside of the converter housing. Front band lever pin plug leaks are generally deposited on the housing and not on the converter.

Page 16

DR AUTOMATIC TRANSMISSION - 48RE 21 - 145

AUTOMATIC TRANSMISSION - 48RE (Continued)

(4) Inspect pump bushing and converter hub. If bushing is scored, replace it. If converter hub is scored, either polish it with crocus cloth or replace converter.

(5) Install new pump seal, O-ring, and gasket. Replace oil pump if cracked, porous or damaged in any way. Be sure to loosen the front band before installing the oil pump, damage to the oil pump seal may occur if the band is still tightened to the front clutch retainer.

(6) Loosen kickdown lever pin access plug three turns. Apply Loctite™ 592, or Permatext No.2to plug threads and tighten plug to 17 N·m (150 in. lbs.) torque.

(7) Adjust front band.

(8) Lubricate pump seal and converter hub with

Fig. 11 Converter Housing Leak Paths

1 - PUMP SEAL 2 - PUMP VENT 3 - PUMP BOLT 4 - PUMP GASKET 5 - CONVERTER HOUSING 6 - CONVERTER 7 - REAR MAIN SEAL LEAK

transmission fluid or petroleum jelly and install converter.

(9) Install transmission and converter housing dust shield.

(10) Lower vehicle.

DIAGNOSIS AND TESTING - DIAGNOSIS CHARTS

TORQUE CONVERTER LEAK POINTS

Possible sources of converter leaks are:

• Leaks at the weld joint around the outside diam-

eter weld.

• Leaks at the converter hub weld.

CONVERTER HOUSING AREA LEAK CORRECTION

(1) Remove converter.

(2) Tighten front band adjusting screw until band is tight around front clutch retainer. This prevents front/rear clutches from coming out when oil pump is removed.

(3) Remove oil pump and remove pump seal. Inspect pump housing drainback and vent holes for obstructions. Clear holes with solvent and wire.

The diagnosis charts provide additional reference when diagnosing a transmission fault. The charts provide general information on a variety of transmission, overdrive unit and converter clutch fault conditions.

The hydraulic flow charts in the Schematics and Diagrams section of this group, outline fluid flow and hydraulic circuitry. Circuit operation is provided for PARK, NEUTRAL, FIRST, SECOND, THIRD, FOURTH, MANUAL FIRST, MANUAL SECOND, and REVERSE gear ranges. Normal working pressures are also supplied for each of the gear ranges.

Page 17

21 - 146 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

DIAGNOSIS CHARTS

CONDITION POSSIBLE CAUSES CORRECTION

HARSH ENGAGEMENT (FROM NEUTRAL TO DRIVE OR REVERSE)

1. Fluid Level Low. 1. Add Fluid

2. Throttle Linkage Mis-adjusted. 2. Adjust linkage - setting may be too long.

3. Mount and Driveline Bolts Loose. 3. Check engine mount, transmission mount, propeller shaft, rear spring to body bolts, rear control arms, crossmember and axle bolt torque. Tighten loose bolts and replace missing bolts.

4. U-Joint Worn/Broken. 4. Remove propeller shaft and replace U-Joint.

5. Axle Backlash Incorrect. 5. Check per Service Manual. Correct as needed.

6. Hydraulic Pressure Incorrect. 6. Check pressure. Remove, overhaul or adjust valve body as needed.

7. Band Mis-adjusted. 7. Adjust rear band.

8. Valve Body Check Balls Missing. 8. Inspect valve body for proper check ball installation.

9. Axle Pinion Flange Loose. 9. Replace nut and check pinion threads before installing new nut. Replace pinion gear if threads are damaged.

10. Clutch, band or planetary

component damaged.

11. Converter Clutch Faulty. 11. Replace converter and flush cooler and

10. Remove, disassemble and repair transmission as necessary.

line before installing new converter.

Page 18

DR AUTOMATIC TRANSMISSION - 48RE 21 - 147

AUTOMATIC TRANSMISSION - 48RE (Continued)

CONDITION POSSIBLE CAUSES CORRECTION

DELAYED ENGAGEMENT (FROM NEUTRAL TO DRIVE OR REVERSE)

NO DRIVE RANGE (REVERSE OK)

1. Fluid Level Low. 1. Correct level and check for leaks.

2. Filter Clogged. 2. Change filter.

3. Gearshift Linkage Mis-adjusted. 3. Adjust linkage and repair linkage if worn or damaged.

4. Torque Converter Drain Back (Oil

drains from torque converter into transmission sump).

5. Rear Band Mis-adjusted. 5. Adjust band.

6. Valve Body Filter Plugged. 6. Replace fluid and filter. If oil pan and old

7. Oil Pump Gears Worn/Damaged. 7. Remove transmission and replace oil

8. Governor Circuit and Solenoid

Valve Electrical Fault.

9. Hydraulic Pressure Incorrect. 9. Perform pressure test, remove

10. Reaction Shaft Seal Rings

Worn/Broken.

11. Rear Clutch/Input Shaft, Rear

Clutch Seal Rings Damaged.

12. Regulator Valve Stuck. 12. Clean.

13. Cooler Plugged. 13. Transfer case failure can plug cooler.

1. Fluid Level Low. 1. Add fluid and check for leaks if drive is

2. Gearshift Linkage/Cable

Loose/Misadjusted.

3. Rear Clutch Burnt. 3. Remove and disassemble transmission

4. Valve Body Malfunction. 4. Remove and disassemble valve body.

5. Transmission Overrunning Clutch

Broken.

6. Input Shaft Seal Rings Worn/

Damaged.

7. Front Planetary Failed Broken. 7. Remove and repair.

4. If vehicle moves normally after 5 seconds after shifting into gear, no repair is necessary. If longer, inspect pump bushing for wear. Replace pump house.

fluid were full of clutch disc material and/or metal particles, overhaul will be necessary.

pump.

8. Test with DRBT scan tool and repair as required.

transmission and repair as needed.

10. Remove transmission, remove oil pump and replace seal rings.

11. Remove and disassemble transmission and repair as necessary.

restored.

2. Repair or replace linkage components.

and rear clutch and seals. Repair/replace worn or damaged parts as needed.

Replace assembly if any valves or bores are damaged.

5. Remove and disassemble transmission. Replace overrunning clutch.

6. Remove and disassemble transmission. Replace seal rings and any other worn or damaged parts.

Page 19

21 - 148 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

CONDITION POSSIBLE CAUSES CORRECTION

NO DRIVE OR REVERSE (VEHICLE WILL NOT MOVE)

SHIFTS DELAYED OR ERRATIC (SHIFTS ALSO HARSH AT TIMES)

1. Fluid Level Low. 1. Add fluid and check for leaks if drive is restored.

2. Gearshift Linkage/Cable

Loose/Misadjusted.

3. U-Joint/Axle/Transfer Case

Broken.

4. Filter Plugged. 4. Remove and disassemble transmission.

5. Oil Pump Damaged. 5. Perform pressure test to confirm low

6. Valve Body Malfunctioned. 6. Check and inspect valve body. Replace

7. Transmission Internal Component

Damaged.

8. Park Sprag not Releasing - Check

Stall Speed, Worn/Damaged/Stuck.

9. Torque Converter Damage. 9. Inspect and replace as required.

1. Fluid Level Low/High. 1. Correct fluid level and check for leaks if

2. Fluid Filter Clogged. 2. Replace filter. If filter and fluid contained

3. Throttle Linkage Mis-adjusted. 3. Adjust linkage as described in service

4. Throttle Linkage Binding. 4. Check cable for binding. Check for return

5. Gearshift Linkage/Cable

Mis-adjusted.

6. Clutch or Servo Failure. 6. Remove valve body and air test clutch,

7. Governor Circuit Electrical Fault. 7. Test using DRBT scan tool and repair as

8. Front Band Mis-adjusted. 8. Adjust band.

9. Pump Suction Passage Leak. 9. Check for excessive foam on dipstick

2. Inspect, adjust and reassemble linkage as needed. Replace worn/damaged parts.

3. Perform preliminary inspection procedure for vehicle that will not move. Refer to procedure in diagnosis section.

Repair or replace failed components as needed. Replace filter. If filter and fluid contained clutch material or metal particles, an overhaul may be necessary. Perform lube flow test. Flush oil. Replace cooler as necessary.

pressure. Replace pump body assembly if necessary.

valve body (as assembly) if any valve or bore is damaged. Clean and reassemble correctly if all parts are in good condition.

7. Remove and disassemble transmission. Repair or replace failed components as needed.

8. Remove, disassemble, repair.

low.

clutch material or metal particles, an overhaul may be necessary. Perform lube flow test.

section.

to closed throttle at transmission.

5. Adjust linkage/cable as described in service section.

and band servo operation. Disassemble and repair transmission as needed.

required.

after normal driving. Check for loose pump bolts, defective gasket. Replace pump assembly if needed.

Page 20

DR AUTOMATIC TRANSMISSION - 48RE 21 - 149

AUTOMATIC TRANSMISSION - 48RE (Continued)

CONDITION POSSIBLE CAUSES CORRECTION

NO REVERSE (D RANGES OK)

HAS FIRST/REVERSE ONLY (NO 1-2 OR 2-3 UPSHIFT)

MOVES IN 2ND OR 3RD GEAR, ABRUPTLY DOWNSHIFTS TO LOW

NO LOW GEAR (MOVES IN 2ND OR 3RD GEAR ONLY)

1. Gearshift Linkage/Cable

Mis-adjusted/Damaged.

2. Park Sprag Sticking. 2. Replace overdrive annulus gear.

3. Rear Band Mis-adjusted/Worn. 3. Adjust band; replace.

4. Valve Body Malfunction. 4. Remove and service valve body. Replace

5. Rear Servo Malfunction. 5. Remove and disassemble transmission.

6. Direct Clutch in Overdrive Worn. 6. Disassemble overdrive. Replace worn or

7. Front Clutch Burnt. 7. Remove and disassemble transmission.

1. Governor Circuit Electrical Fault. 1. Test using DRBT scan tool and repair as

2. Valve Body Malfunction. 2. Repair stuck 1-2 shift valve or governor

3. Front Servo/Kickdown Band

Damaged/Burned.

1. Valve Body Malfunction. 1. Remove, clean and inspect. Look for

1. Governor Circuit Electrical Fault. 1. Test with DRBT scan tool and repair as

2. Valve Body Malfunction. 2. Remove, clean and inspect. Look for

3. Front Servo Piston Cocked in

Bore.

4. Front Band Linkage Malfunction 4. Inspect linkage and look for bind in

1. Repair or replace linkage parts as needed.

valve body if any valves or valve bores are worn or damaged.

Replace worn/damaged servo parts as necessary.

damaged parts.

Replace worn, damaged clutch parts as required.

required.

plug.

3. Repair/replace.

stuck 1-2 valve or governor plug.

required.

sticking 1-2 shift valve, 2-3 shift valve, governor plug or broken springs.

3. Inspect servo and repair as required.

linkage.

Page 21

21 - 150 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

CONDITION POSSIBLE CAUSES CORRECTION

NO KICKDOWN OR NORMAL DOWNSHIFT

STUCK IN LOW GEAR (WILL NOT UPSHIFT)

CREEPS IN NEUTRAL 1. Gearshift Linkage Mis-adjusted. 1. Adjust linkage.

1. Throttle Linkage Mis-adjusted. 1. Adjust linkage.

2. Accelerator Pedal Travel

Restricted.

3. Valve Body Hydraulic Pressures

Too High or Too Low Due to Valve Body Malfunction or Incorrect Hydraulic Control Pressure Adjustments.

4. Governor Circuit Electrical Fault. 4. Test with DRBT scan tool and repair as

5. Valve Body Malfunction. 5. Perform hydraulic pressure tests to

6. TPS Malfunction. 6. Replace sensor, check with DRBT scan

7. PCM Malfunction. 7. Check with DRBT scan tool and replace

8. Valve Body Malfunction. 8. Repair sticking 1-2, 2-3 shift valves,

1. Throttle Linkage Mis-adjusted/

Stuck.

2. Gearshift Linkage Mis-adjusted. 2. Adjust linkage and repair linkage if worn

3. Governor Component Electrical

Fault.

4. Front Band Out of Adjustment. 4. Adjust Band.

5. Clutch or Servo Malfunction. 5. Air pressure check operation of clutches

2. Rear Clutch Dragging/Warped. 2. Disassemble and repair.

3. Valve Body Malfunction. 3. Perform hydraulic pressure test to

2. Verify floor mat is not under pedal, repair worn accelerator cable or bent brackets.

3. Perform hydraulic pressure tests to determine cause and repair as required. Correct valve body pressure adjustments as required.

required.

determine cause and repair as required. Correct valve body pressure adjustments as required.

tool.

if required.

governor plugs, 3-4 solenoid, 3-4 shift valve, 3-4 timing valve.

1. Adjust linkage and repair linkage if worn or damaged. Check for binding cable or missing return spring.

or damaged.

3. Check operating pressures and test with DRBT scan tool, repair faulty component.

and bands. Repair faulty component.

determine cause and repair as required.

Page 22

DR AUTOMATIC TRANSMISSION - 48RE 21 - 151

AUTOMATIC TRANSMISSION - 48RE (Continued)

CONDITION POSSIBLE CAUSES CORRECTION

BUZZING NOISE 1. Fluid Level Low 1. Add fluid and check for leaks.

2. Shift Cable Mis-assembled. 2. Route cable away from engine and bell housing.

3. Valve Body Mis-assembled. 3. Remove, disassemble, inspect valve body. Reassemble correctly if necessary. Replace assembly if valves or springs are damaged. Check for loose bolts or screws.

4. Pump Passages Leaking. 4. Check pump for porous casting, scores on mating surfaces and excess rotor clearance. Repair as required. Loose pump bolts.

5. Cooling System Cooler Plugged. 5. Flow check cooler circuit. Repair as needed.

6. Overrunning Clutch Damaged. 6. Replace clutch.

SLIPS IN REVERSE ONLY 1. Fluid Level Low. 1. Add fluid and check for leaks.

2. Gearshift Linkage Mis-adjusted. 2. Adjust linkage.

3. Rear Band Mis-adjusted. 3. Adjust band.

4. Rear Band Worn. 4. Replace as required.

5. Overdrive Direct Clutch Worn. 5. Disassemble overdrive. Repair as needed.

6. Hydraulic Pressure Too Low. 6. Perform hydraulic pressure tests to determine cause.

7. Rear Servo Leaking. 7. Air pressure check clutch-servo operation and repair as required.

8. Band Linkage Binding. 8. Inspect and repair as required.

SLIPS IN FORWARD DRIVE RANGES

SLIPS IN LOW GEAR 9D9 ONLY, BUT NOT IN MANUAL 1 POSITION

1. Fluid Level Low. 1. Add fluid and check for leaks.

2. Fluid Foaming. 2. Check for high oil level, bad pump gasket or seals, dirt between pump halves and loose pump bolts. Replace pump if necessary.

3. Throttle Linkage Mis-adjusted. 3. Adjust linkage.

4. Gearshift Linkage Mis-adjusted. 4. Adjust linkage.

5. Rear Clutch Worn. 5. Inspect and replace as needed.

6. Low Hydraulic Pressure Due to

Worn Pump, Incorrect Control Pressure Adjustments, Valve Body Warpage or Malfunction, Sticking, Leaking Seal Rings, Clutch Seals Leaking, Servo Leaks, Clogged Filter or Cooler Lines.

7. Rear Clutch Malfunction, Leaking

Seals or Worn Plates.

8. Overrunning Clutch Worn, Not

Holding (Slips in 1 Only). Overrunning Clutch Faulty. Replace overrunning clutch.

6. Perform hydraulic and air pressure tests to determine cause.

7. Air pressure check clutch-servo operation and repair as required.

8. Replace Clutch.

Page 23

21 - 152 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

CONDITION POSSIBLE CAUSES CORRECTION

GROWLING, GRATING OR SCRAPING NOISES

DRAGS OR LOCKS UP 1. Fluid Level Low. 1. Check and adjust level.

NO 4-3 DOWNSHIFT 1. Circuit Wiring and/or Connectors

1. Drive Plate Broken. 1. Replace.

2. Torque Converter Bolts Hitting

Dust Shield.

3. Planetary Gear Set Broken/

Seized.

4. Overrunning Clutch Worn/Broken. 4. Inspect and check for debris in oil pan.

5. Oil Pump Components Scored/

Binding.

6. Output Shaft Bearing or Bushing

Damaged.

7. Clutch Operation Faulty. 7. Perform air pressure check and repair as

8. Front and Rear Bands Mis-

adjusted.

2. Clutch Dragging/Failed 2. Air pressure check clutch operation and

3. Front or Rear Band Mis-adjusted. 3. Adjust bands.

4. Case Leaks Internally. 4. Check for leakage between passages in

5. Servo Band or Linkage

Malfunction.

6. Overrunning Clutch Worn. 6. Remove and inspect clutch. Repair as

7. Planetary Gears Broken. 7. Remove, inspect and repair as required

8. Converter Clutch Dragging. 8. Check for plugged cooler. Perform flow

Shorted.

2. PCM Malfunction. 2. Check PCM operation with DRBT scan

3. TPS Malfunction 3. Check TPS with DRBT scan tool at PCM.

4. Lockup Solenoid Not Venting. 4. Remove valve body and replace solenoid

5. Overdrive Solenoid Not Venting. 5. Remove valve body and replace solenoid

6. Valve Body Valve Sticking. 6. Repair stuck 3-4 shift valve or lockup

2. Dust shield bent. Replace or repair.

3. Check for debris in oil pan and repair as required.

Repair as required.

5. Remove, inspect and repair as required.

6. Remove, inspect and repair as required.

required.

8. Adjust bands.

repair as required.

case.

5. Air pressure check servo operation and repair as required.

required.

(look for debris in oil pan).

check. Inspect pump for excessive side clearance. Replace pump as required.

1. Test wiring and connectors with test lamp and volt/ohmmeter. Repair wiring as necessary. Replace connectors and/or harnesses as required.

tool. Replace PCM only if faulty.

assembly if plugged or shorted.

if plugged or shorted.

timing valve.

Page 24

DR AUTOMATIC TRANSMISSION - 48RE 21 - 153

AUTOMATIC TRANSMISSION - 48RE (Continued)

CONDITION POSSIBLE CAUSES CORRECTION

NO 4-3 DOWNSHIFT WHEN CONTROL SWITCH IS TURNED OFF

CLUNK NOISE FROM DRIVELINE ON CLOSED THROTTLE 4-3 DOWNSHIFT

3-4 UPSHIFT OCCURS IMMEDIATELY AFTER 2-3 SHIFT

WHINE/NOISE RELATED TO ENGINE SPEED

1. Control Switch Open/Shorted. 1. Test and replace switch if faulty.

2. Overdrive Solenoid Connector

Shorted.

3. PCM Malfunction. 3. Test with DRBT scan tool. Replace PCM

4. Valve Body Stuck Valves. 4. Repair stuck 3-4, lockup or lockup timing

1. Transmission Fluid Low. 1. Add Fluid.

2. Throttle Cable Mis-adjusted. 2. Adjust cable.

3. Overdrive Clutch Select Spacer

Wrong Spacer.

1. Overdrive Solenoid Connector or

Wiring Shorted.

2. TPS Malfunction. 2. Test TPS and replace as necessary.

3. PCM Malfunction. 3. Test PCM with DRBT scan tool and

4. Overdrive Solenoid Malfunction. 4. Replace solenoid.

5. Valve Body Malfunction. 5. Remove, disassemble, clean and inspect

1. Fluid Level Low. 1. Add fluid and check for leaks.

2. Shift Cable Incorrect Routing. 2. Check shift cable for correct routing.

2. Test solenoids and replace if seized or shorted.

if faulty.

valve.

3. Replace overdrive piston thrust plate spacer.

1. Test connector and wiring for loose connections, shorts or ground and repair as needed.

Check with DRBT scan tool.

replace controller if faulty.

valve body components. Make sure all valves and plugs slide freely in bores. Polish valves with crocus cloth if needed.

Should not touch engine or bell housing.

Page 25

21 - 154 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

CONDITION POSSIBLE CAUSES CORRECTION

NO 3-4 UPSHIFT 1. O/D Switch In OFF Position. 1. Turn control switch to ON position.

2. Overdrive Circuit Fuse Blown. 2. Replace fuse. Determine why fuse failed and repair as necessary (i.e., shorts or grounds in circuit).

3. O/D Switch Wire Shorted/Open

Cut.

4. Distance or Coolant Sensor

Malfunction.

5. TPS Malfunction. 5. Check with DRBT scan tool and replace

6. Neutral Sense to PCM Wire

Shorted/Cut.

7. PCM Malfunction. 7. Check with DRBT scan tool and replace

8. Overdrive Solenoid Shorted/Open. 8. Replace solenoid if shorted or open and

9. Solenoid Feed Orifice in Valve

Body Blocked.

10. Overdrive Clutch Failed. 10. Disassemble overdrive and repair as

11. Hydraulic Pressure Low. 11. Pressure test transmission to determine

12. Valve Body Valve Stuck. 12. Repair stuck 3-4 shift valve, 3-4 timing

13. O/D Piston Incorrect Spacer. 13. Remove unit, check end play and install

14. Overdrive Piston Seal Failure. 14. Replace both seals.

15. O/D Check Valve/Orifice Failed. 15. Check for free movement and secure

3. Check wires/connections with 12V test lamp and voltmeter. Repair damaged or loose wire/connection as necessary.

4. Check with DRBT scan tool and repair or replace as necessary.

if necessary.

6. Test switch/sensor as described in service section and replace if necessary. Engine no start.

if necessary.

repair loose or damaged wires (DRBT scan tool).

9. Remove, disassemble, and clean valve body thoroughly. Check feed orifice.

needed.

cause.

valve.

correct spacer.

assembly (in piston retainer). Check ball bleed orifice.

Page 26

DR AUTOMATIC TRANSMISSION - 48RE 21 - 155

AUTOMATIC TRANSMISSION - 48RE (Continued)

CONDITION POSSIBLE CAUSES CORRECTION

SLIPS IN OVERDRIVE FOURTH GEAR

DELAYED 3-4 UPSHIFT (SLOW TO ENGAGE)

TORQUE CONVERTER LOCKS UP IN SECOND AND/OR THIRD GEAR

HARSH 1-2, 2-3, 3-4 OR 3-2 SHIFTS

1. Fluid Level Low. 1. Add fluid and check for leaks.

2. Overdrive Clutch Pack Worn. 2. Remove overdrive unit and rebuild clutch pack.

3. Overdrive Piston Retainer Bleed

Orifice Blown Out.

4. Overdrive Piston or Seal

Malfunction.

5. 3-4 Shift Valve, Timing Valve or

Accumulator Malfunction.

6. Overdrive Unit Thrust Bearing

Failure.

7. O/D Check Valve/Bleed Orifice

Failure.

1. Fluid Level Low. 1. Add fluid and check for leaks.

2. Throttle Valve Cable Mis-adjusted. 2. Adjust throttle valve cable.

3. Overdrive Clutch Pack Worn/

Burnt.

4. TPS Faulty. 4. Test with DRBT scan tool and replace as

5. Overdrive Clutch Bleed Orifice

Plugged.

6. Overdrive Solenoid or Wiring

Shorted/Open.

7. Overdrive Excess Clearance. 7. Remove unit. Measure end play and

8. O/D Check Valve Missing or

Stuck. Lockup Solenoid, Relay or Wiring

Shorted/Open.

Lockup Solenoid Malfunction. Remove valve body and replace solenoid

3. Disassemble transmission, remove retainer and replace orifice.

4. Remove overdrive unit. Replace seals if worn. Replace piston if damaged. If piston retainer is damaged, remove and disassemble the transmission.

5. Remove and overhaul valve body. Replace accumulator seals. Make sure all valves operate freely in bores and do not bind or stick. Make sure valve body screws are correctly tightened and separator plates are properly positioned.

6. Disassemble overdrive unit and replace thrust bearing (NO. 1 thrust bearing is between overdrive piston and clutch hub; NO. 2 thrust bearing is between the planetary gear and the direct clutch spring plate; NO. 3 thrust bearing is between overrunning clutch hub and output shaft).

7. Check for function/secure orifice insert in O/D piston retainer.

3. Remove unit and rebuild clutch pack.

necessary

5. Disassemble transmission and replace orifice.

6. Test solenoid and check wiring for loose/corroded connections or shorts/ grounds. Replace solenoid if faulty and repair wiring if necessary.

select proper spacer.

8. Check for presence of check valve. Repair or replace as required.

Test solenoid, relay and wiring for continuity, shorts or grounds. Replace solenoid and relay if faulty. Repair wiring and connectors as necessary.

assembly.

Page 27

21 - 156 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

CONDITION POSSIBLE CAUSES CORRECTION

NO START IN PARK OR NEUTRAL

NO REVERSE (OR SLIPS IN REVERSE)

1. Gearshift Linkage/Cable

Mis-adjusted.

2. Neutral Sense Wire Open/Cut. 2. Check continuity with test lamp. Repair

3. Park/Neutral Switch, or

Transmission Range Sensor Faulty.

4. Park/Neutral Switch, or

Transmission Range Sensor Connection Faulty.

5. Valve Body Manual Lever

Assembly Bent/Worn/Broken.

1. Direct Clutch Pack (front clutch)

Worn.

2. Rear Band Mis-adjusted. 2. Adjust band.

3. Front Clutch Malfunctioned/

Burned.

4. Overdrive Thrust Bearing Failure. 4. Disassemble geartrain and replace

5. Direct Clutch Spring Collapsed/

Broken.

1. Adjust linkage/cable.

as required.

3. Refer to service section for test and replacement procedure.

4. Connectors spread open. Repair.

5. Inspect lever assembly and replace if damaged.

1. Disassemble unit and rebuild clutch pack.

3. Air-pressure test clutch operation. Remove and rebuild if necessary.

bearings.

5. Remove and disassemble unit. Check clutch position and replace spring.

Page 28

DR AUTOMATIC TRANSMISSION - 48RE 21 - 157

AUTOMATIC TRANSMISSION - 48RE (Continued)

CONDITION POSSIBLE CAUSES CORRECTION

OIL LEAKS. 1. Fluid Lines and Fittings Loose/

Leaks/Damaged.

2. Fill Tube (where tube enters case)

Leaks/Damaged.

3. Pressure Port Plug Loose

Loose/Damaged.

4. Pan Gasket Leaks. 4. Tighten pan screws (150 in. lbs.). If leaks

5. Valve Body Manual Lever Shaft

Seal Leaks/Worn.

6. Rear Bearing Access Plate Leaks. 6. Replace gasket. Tighten screws.

7. Gasket Damaged or Bolts are

Loose.

8. Adapter/Extension Gasket

Damaged Leaks/Damaged.

9. Park/Neutral Switch, or

Transmission Range Sensor Leaks/Damaged.

10. Converter Housing Area Leaks. 10. Check for leaks at seal caused by worn

11. Pump Seal Leaks/Worn/

Damaged.

12. Torque Converter Weld

Leak/Cracked Hub.

13. Case Porosity Leaks. 13. Replace case.

NOISY OPERATION IN FOURTH GEAR ONLY

1. Overdrive Clutch Discs, Plates or

Snap Rings Damaged.

2. Overdrive Piston or Planetary

Thrust Bearing Damaged.

3. Output Shaft Bearings Scored/

Damaged.

4. Planetary Gears Worn/Chipped. 4. Remove and overhaul overdrive unit.

5. Overdrive Unit Overrunning Clutch

Rollers Worn/Scored.

1. Tighten fittings. If leaks persist, replace fittings and lines if necessary.

2. Replace tube seal. Inspect tube for cracks in fill tube.

3. Tighten to correct torque. Replace plug or reseal if leak persists.

persist, replace gasket.

5. Replace shaft seal.

7. Replace bolts or gasket or tighten both.

8. Replace gasket.

9. Replace switch and gasket.

seal or burr on converter hub (cutting seal), worn bushing, missing oil return, oil in front pump housing or hole plugged. Check for leaks past O-ring seal on pump or past pump-to-case bolts; pump housing porous, oil coming out vent due to overfill or leak past front band shaft access plug.

11. Replace seal.

12. Replace converter.

1. Remove unit and rebuild clutch pack.

2. Remove and disassemble unit. Replace either thrust bearing if damaged.

3. Remove and disassemble unit. Replace either bearing if damaged.

5. Remove and overhaul overdrive unit.

Page 29

21 - 158 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

STANDARD PROCEDURE - ALUMINUM THREAD REPAIR

Damaged or worn threads in the aluminum transmission case and valve body can be repaired by the use of Heli-Coils™, or equivalent. This repair consists of drilling out the worn-out damaged threads. Then tap the hole with a special Heli-Coil™ tap, or equivalent, and installing a Heli-Coil™ insert, or equivalent, into the hole. This brings the hole back to its original thread size.

Heli-Coil™, or equivalent, tools and inserts are readily available from most automotive parts suppliers.

REMOVAL

NOTE: The overdrive unit can be removed and serviced separately. It is not necessary to remove the entire transmission assembly to perform overdrive unit repairs.

(1) Disconnect battery negative cable.

(2) Raise vehicle.

(3) Remove the transfer case skid plate (Fig. 12), if equipped.

(4) Disconnect and lower or remove necessary

exhaust components.

(5) Remove engine-to-transmission struts. (6) Remove starter motor. (Refer to 8 - ELECTRI-

CAL/STARTING/STARTER MOTOR - REMOVAL)

(7) Disconnect and remove the crankshaft position sensor. (Refer to 14 - FUEL SYSTEM/FUEL INJECTION/CRANKSHAFT POSITION SENSOR REMOVAL) Retain the sensor attaching bolts.

(8) If transmission is being removed for overhaul, remove transmission oil pan, drain fluid and reinstall pan.

(9) Remove torque converter access cover.

(10) Rotate crankshaft in clockwise direction until converter bolts are accessible. Then remove bolts one at a time. Rotate crankshaft with socket wrench on dampener bolt.

(11) Mark propeller shaft and axle yokes for assembly alignment. Then disconnect and remove propeller shaft. On4x4models, remove both propeller shafts. (Refer to 3 - DIFFERENTIAL & DRIVELINE/PROPELLER SHAFT/PROPELLER SHAFT REMOVAL)

(12) Disconnect wires from the transmission range sensor and transmission solenoid connector.

(13) Disconnect gearshift cable (Fig. 13) from the transmission.

Fig. 12 Transfer Case Skid Plate

1 - FRAME RAIL 2 - SKID PLATE 3 - BOLTS (6)

Fig. 13 Gearshift Cable At Transmission

1 - GEARSHIFT CABLE 2 - TRANSMISSION MANUAL LEVER 3 - CABLE SUPPORT BRACKET

Page 30

DR AUTOMATIC TRANSMISSION - 48RE 21 - 159

AUTOMATIC TRANSMISSION - 48RE (Continued)

(14) Disconnect throttle valve cable from transmis-

sion bracket and throttle valve lever.

(15) On 4X4 models, disconnect shift rod from

transfer case shift lever.

(16) Support rear of engine with safety stand or

jack.

(17) Raise transmission slightly with service jack

to relieve load on crossmember and supports.

(18) Remove bolts securing rear support and cushion (Fig. 14) and (Fig. 15) to transmission and crossmember and remove rear support.

Fig. 15 Engine Rear Mount - 4X4 Automatic

Transmission

1 - TRANSMISSION 2 - ENGINE REAR MOUNT 3 - BOLT

Fig. 14 Engine Rear Mount - 4X2 Automatic

Transmission

1 - ENGINE REAR MOUNT 2 - BOLT 3 - NUT 4 - THROUGH BOLT NUT 5 - TRANSMISSION

(19) Remove bolts attaching crossmember to frame and remove crossmember.

(20) On 4X4 models, remove transfer case with transmission jack or aid of helper.

(21) Disconnect fluid cooler lines at transmission.

(22) Remove fill tube bracket bolts and pull tube out of transmission. Retain fill tube seal. On 4X4 models, it will also be necessary to remove bolt attaching transfer case vent tube to converter housing (Fig. 16).

(23) Remove all converter housing bolts.

(24) Carefully work transmission and torque converter assembly rearward off engine block dowels.

(25) Lower transmission and remove assembly from under the vehicle.

(26) To remove torque converter, remove C-clamp from edge of bell housing and carefully slide torque converter out of the transmission.

Fig. 16 Fill Tube Attachment

1 - TRANSFER CASE VENT TUBE 2 - FILL TUBE (V8) 3 - TUBE SEAL 4 - FILL TUBE (V6)

Page 31

21 - 160 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

DISASSEMBLY

(1) Clean exterior of transmission with suitable solvent or pressure washer.

(2) Place transmission in vertical position.

(3) Measure the input shaft end play as follows (Fig. 17).

(a) Attach Adapter 8266-5 to Handle 8266-8. (b) Attach dial indicator C-3339 to Handle

8266-8.

(c) Install the assembled tool onto the input shaft of the transmission and tighten the retaining screw on Adapter 8266-5 to secure it to the input shaft.

(d) Position the dial indicator plunger against a flat spot on the oil pump and zero the dial indicator.

(e) Move input shaft in and out and record reading. Record the maximum travel for assembly reference

(7) Remove filter from valve body (Fig. 18). Keep filter screws separate from other valve body screws. Filter screws are longer and should be kept with filter.

Fig. 18 Oil Filter Removal

1 - OIL FILTER 2 - VALVE BODY 3 - FILTER SCREWS (2)

Fig. 17 Checking Input Shaft End Play

1 - TOOL 8266-8 2 - TOOL 8266-5 3 - TOOL C-3339

(4) Remove the overdrive unit from the main transmission case. If overdrive unit is not to be serviced, install Alignment Shaft 6227-2 into the overdrive unit to prevent misalignment of the overdrive clutches during service of main transmission components.

(5) Remove throttle and shift levers from valve body manual shaft and throttle lever shaft.

(6) Remove transmission oil pan and gasket.

(8) Remove the transmission range sensor.

(9) Remove hex head bolts attaching valve body to transmission case (Fig. 19). A total of 10 bolts are used. Note different bolt lengths for assembly reference.

Fig. 19 Valve Body Bolt Locations

1 - VALVE BODY BOLTS 2 - VALVE BODY BOLTS

Page 32

DR AUTOMATIC TRANSMISSION - 48RE 21 - 161

AUTOMATIC TRANSMISSION - 48RE (Continued)

(10) Remove valve body assembly. Push valve body harness connector out of case. Then work park rod and valve body out of case (Fig. 20).

Fig. 22 Front Band Lever Pin Access Plug

1 - FRONT BAND REACTION PIN ACCESS PLUG 2 - 1/4 DRIVE EXTENSION AND RATCHET

(14) Remove oil pump and reaction shaft support

assembly as follows:

(a) Tighten front band adjusting screw until

band is tight around front clutch retainer (Fig. 23).

Fig. 20 Valve Body Removal

1 - GOVERNOR PRESSURE SENSOR 2 - VALVE BODY 3 - PARK ROD 4 - ACCUMULATOR PISTON 5 - GOVERNOR PRESSURE SOLENOID

This will prevent retainer from coming out with pump and possibly damaging clutch or pump components.

(11) Remove accumulator outer spring, piston and inner spring (Fig. 21). Note position of piston and springs for assembly reference. Remove and discard piston seals if worn or cut.

(12) Remove pump oil seal with suitable pry tool or slide-hammer mounted screw.

(13) Remove front band lever pin access plug (Fig.

22). Use square end of 1/4 in. drive extension to remove plug as shown.

Fig. 21 Accumulator Component Removal

1 - ACCUMULATOR PISTON 2 - OUTER SPRING 3 - INNER SPRING

Fig. 23 Tightening Front Band To Hold Front Clutch

In Place

1 - LOCK-NUT 2 - FRONT BAND ADJUSTER

Page 33

21 - 162 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

(b) Remove oil pump bolts. (c) Thread Slide Hammer Tools C-3752 into

threaded holes in flange of oil pump housing (Fig.

24). (d) Remove oil pump and reaction shaft support

by bumping slide hammers outward alternately to pull pump from case (Fig. 25). (15) Remove oil pump gasket (Fig. 26). Note gas-

ket position in case for assembly reference.

(16) Loosen front band adjusting screw until band

is completely loose.

(17) Remove front band strut and anchor (Fig. 27).

Fig. 26 Oil Pump Gasket

1 - OIL PUMP GASKET

Fig. 24 Oil Pump Removal Tools

1 - PUMP HOUSING 2 - SLIDE HAMMER TOOLS (THREAD INTO PUMP HOUSING)

Fig. 27 Front Band Linkage

1 - LEVER 2 - STRUT 3 - ANCHOR 4 - FRONT BAND

Fig. 25 Oil Pump Removal

1 - OIL PUMP AND REACTION SHAFT SUPPORT

Page 34

DR AUTOMATIC TRANSMISSION - 48RE 21 - 163

AUTOMATIC TRANSMISSION - 48RE (Continued)

(18) Squeeze front band together slightly and slide

band over front clutch retainer and out of case (Fig.

28).

Fig. 28 Front Band Removal

1 - FRONT BAND 2 - FRONT CLUTCH RETAINER

(19) Remove front and rear clutch assemblies as a

unit (Fig. 29).

(20) Remove front band reaction pin and lever. Start pin through lever and out of case bore with drift or punch. Then use pencil magnet to withdraw pin completely (Fig. 30).

(21) Remove intermediate shaft thrust washer. Triangular shaped washer will either be on shaft pilot hub or in rear clutch retainer (Fig. 31).

Fig. 29 Removing Front/Rear Clutch Assemblies

1 - FRONT AND REAR CLUTCH ASSEMBLIES

Fig. 30 Front Band Lever And Pin

1 - BAND LEVER 2 - USE PENCIL MAGNET TO REMOVE REACTION PIN

Fig. 31 Intermediate Shaft Thrust Washer

1 - THRUST WASHER 2 - INTERMEDIATE SHAFT PILOT HUB

Page 35

21 - 164 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

(22) Remove thrust plate from intermediate shaft

hub (Fig. 32).

(23) Remove intermediate shaft-planetary

geartrain assembly (Fig. 33).

(24) Loosen rear band locknut and loosen adjust-

ing screw 3-4 turns.

(25) Remove snap-ring that retains low-reverse

drum on overdrive piston retainer hub (Fig. 34).

Fig. 34 Low-Reverse Drum Snap-Ring

1 - LOW-REVERSE DRUM 2 - TABBED WASHER 3 - SNAP-RING

(26) Slide low-reverse drum and thrust washer off piston retainer hub and out of rear band (Fig. 35).

Fig. 32 Intermediate Shaft Thrust Plate

1 - SHAFT THRUST PLATE 2 - INTERMEDIATE SHAFT PILOT HUB

Fig. 33 Intermediate Shaft And Planetary Geartrain

1 - INTERMEDIATE SHAFT AND PLANETARY GEAR TRAIN ASSEMBLY

Fig. 35 Low-Reverse Drum And Thrust Washer

1 - LOW-REVERSE DRUM 2 - SPOTFACE FOR WASHER 3 - THRUST WASHER

Page 36

DR AUTOMATIC TRANSMISSION - 48RE 21 - 165

AUTOMATIC TRANSMISSION - 48RE (Continued)

(27) Note that overrunning clutch race will remain

on splines of low-reverse drum after removal (Fig.

36). The race is a permanent press fit on the

hub splines. Do not attempt to remove the race.

(28) Remove overrunning clutch assembly (Fig.

37). Assembly can be removed without displacing rollers and springs if care is exercised. Note position of rollers and springs for assembly reference.

(29) Remove rear band adjusting lever and reac-

tion pin.

(30) Remove rear band.

Fig. 37 Overrunning Clutch

1 - CLUTCH CAM 2 - OVERRUNNING CLUTCH ASSEMBLY

Fig. 36 Overrunning Clutch Race Position On

Low-Reverse Drum

1 - OVERRUNNING CLUTCH RACE 2 - LOW-REVERSE DRUM

(31) Compress front servo rod guide with large C-clamp and Tool C-4470, or Compressor Tool C-3422-B (Fig. 38). Compress guide only enough to permit snap-ring removal (about 1/8 in.).

(32) Remove servo piston snap-ring (Fig. 38). Unseat one end of ring. Then carefully work removal tool around back of ring until free of ring groove.

Exercise caution when removing snap-ring. Servo bore can be scratched or nicked if care is not exercised.

Fig. 38 Front Servo Retaining Snap-Ring

1 - C-CLAMP 2 - FRONT SERVO ROD GUIDE 3 - SNAP-RING 4 - TOOL C-4470

Page 37

21 - 166 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

(33) Remove tools and remove servo piston and spring.

(34) Compress rear servo piston with C-clamp and Tool C-4470, or Valve Spring Compressor C-3422-B (Fig. 39). Compress servo spring retainer only enough to permit snap-ring removal.

(35) Remove servo piston snap-ring (Fig. 39). Start one end of ring out of bore. Then carefully work removal tool around back of snap-ring until free of ring groove. Exercise caution when removing

snap-ring. Servo bore can be scratched or nicked if care is not exercised.

(36) Remove tools and remove rear servo retainer, spring and piston assembly.

INSPECTION

Inspect the case for cracks, porous spots, worn bores, or damaged threads. Damaged threads can be repaired with Helicoil thread inserts. However, the case will have to be replaced if it exhibits any type of damage or wear.

Lubricate the front band adjusting screw threads with petroleum jelly and thread the screw part-way into the case. Be sure the screw turns freely.

Inspect the transmission bushings during overhaul. Bushing condition is important as worn, scored bushings contribute to low pressures, clutch slip and accelerated wear of other components. However, do not replace bushings as a matter of course. Replace bushings only when they are actually worn, or scored.

The use of crocus cloth is permissible where necessary, providing it is used carefully. When used on shafts, or valves, use extreme care to avoid rounding off sharp edges. Sharp edges are vital as they prevent foreign matter from getting between the valve and valve bore.

Do not reuse oil seals, gaskets, seal rings, or O-rings during overhaul. Replace these parts as a matter of course. Also do not reuse snap rings or E-clips that are bent or distorted. Replace these parts as well.

Fig. 39 Rear Servo Retaining Snap-Ring

1 - TOOL C-4470 2 - C-CLAMP 3 - REAR SERVO SPRING RETAINER 4 - RETAINER SNAP-RING

CLEANING

Clean the case in a solvent tank. Flush the case bores and fluid passages thoroughly with solvent. Dry the case and all fluid passages with compressed air. Be sure all solvent is removed from the case and that all fluid passages are clear.

NOTE: Do not use shop towels or rags to dry the case (or any other transmission component) unless they are made from lint-free materials. Lint will stick to case surfaces and transmission components and circulate throughout the transmission after assembly. A sufficient quantity of lint can block fluid passages and interfere with valve body operation.

Lubricate transmission parts with Mopart ATF +4, Automatic Transmission fluid, during overhaul and assembly. Use petroleum jelly to prelubricate seals, O-rings, and thrust washers. Petroleum jelly can also be used to hold parts in place during reassembly.

ASSEMBLY

Do not allow dirt, grease, or foreign material to enter the case or transmission components during assembly. Keep the transmission case and components clean. Also make sure the tools and workbench area used for reassembly operations are equally clean.

Shop towels used for wiping off tools and your hands must be made from lint free materials. Lint will stick to transmission parts and could interfere with valve operation or even restrict fluid passages.

Lubricate transmission clutch and gear components with Mopart ATF +4 during reassembly. Soak clutch discs in transmission fluid before installation.

Use petroleum jelly on piston seals and o-rings to ease installation. Petroleum jelly can also be used to lubricate and hold thrust washers and plates in position during assembly.

Do not use chassis grease, bearing grease, white grease, or similar lubricants on any part.

These types of lubricants can eventually block or restrict fluid passages and valve operation. Use petroleum jelly only.

Do not force parts into place. The transmission components and sub-assemblies are easily installed by hand when properly aligned. If a part seems difficult to install, it is either misaligned or incorrectly

Page 38

DR AUTOMATIC TRANSMISSION - 48RE 21 - 167

AUTOMATIC TRANSMISSION - 48RE (Continued)

assembled. Verify that thrust washers, thrust plates and seal rings are correctly positioned.

The planetary geartrain, front/rear clutch assemblies and oil pump are all much easier to install when the transmission case is upright. Either tilt the case upward with wood blocks, or cut a hole in the bench large enough for the intermediate shaft and rear support. Then lower the shaft and support into the hole and support the rear of the case directly on the bench.

FRONT/REAR SERVO

(1) Lubricate rear servo piston seal with ATF +4. Lubricate servo bore in case with ATF +4.

(2) Install rear servo piston in case. Position piston at slight angle to bore and insert piston with twisting motion (Fig. 40).

(3) Install rear servo spring and retainer in case bore (Fig. 41). Be sure spring is seated on piston.

(4) Compress rear servo piston with C-clamp or Valve Spring Compressor C-3422-B and install servo piston snap-ring (Fig. 42).

(5) Lubricate front servo piston components and servo bore in case with transmission fluid.

(6) Install front servo piston in bore. Carefully “run” small, suitable tool around piston ring to press it back into groove and ease installation (Fig. 43). Rotate piston into bore at same time. Rock piston slightly to ease piston ring past snap-ring groove and into bore.

Fig. 41 Rear Servo Piston Spring And Retainer

1 - PISTON SPRING 2 - REAR SERVO PISTON 3 - SPRING RETAINER

Fig. 40 Rear Servo Piston

1 - REAR SERVO PISTON

Fig. 42 Rear Servo Snap Ring

1 - TOOL C-4470 2 - C-CLAMP 3 - REAR SERVO SPRING RETAINER 4 - RETAINER SNAP-RING

Page 39

21 - 168 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

Fig. 44 Front Servo Rod Guide And Snap Ring

1 - C-CLAMP 2 - ROD GUIDE 3 - SMALL SCREWDRIVER 4 - ROD GUIDE SNAP-RING 5 - TOOL SP-5560

Fig. 43 Front Servo Piston

1 - USE SUITABLE TOOL TO HELP SEAT PISTON RING 2 - FRONT SERVO PISTON

(7) Bottom front servo piston in bore and install servo spring.

(8) Install front servo piston rod guide as follows:

(a) Place Tool SP-5560 (or similar size tool) on

guide and position C-clamp on tool and case (Fig.

44). (b) Slowly compress rod guide while simulta-

neously easing seal ring into bore with suitable tool. (9) Install rod guide snap-ring (Fig. 44).

(7) Install rear band adjusting lever and pivot pin. Be sure lever and the single lug on the band are aligned and engaged before seating band pivot pin in case.

OVERRUNNING CLUTCH, REAR BAND, AND LOW-REVERSE DRUM

(1) Install overrunning clutch components if not

yet installed.

(2) Position rear band reaction pin and band in case. Be sure that the twin lugs on the band are seated against the reaction pin.

(3) Install low-reverse drum. Slide drum through rear band, onto piston retainer hub and into engagement with overrunning clutch and race.

(4) Install thrust washer in low-reverse drum spotface (Fig. 45). Use petroleum jelly to hold washer in place.

(5) Install snap-ring that secures low-reverse drum to piston retainer hub (Fig. 45).

(6) Insert the rear band pivot pin part way into the case.

Fig. 45 Low-Reverse Drum Snap Ring

1 - LOW-REVERSE DRUM 2 - TABBED WASHER 3 - SNAP-RING

Page 40

DR AUTOMATIC TRANSMISSION - 48RE 21 - 169

AUTOMATIC TRANSMISSION - 48RE (Continued)

PLANETARY GEARTRAIN, FRONT/REAR CLUTCH, AND FRONT BAND

(1) Remove Alignment Shaft 6227-2, if installed previously.

(2) Install assembled intermediate shaft and planetary geartrain (Fig. 46). Support shaft carefully

during installation. Do not allow shaft bearing/ bushing surfaces to become nicked or scratched.

(3) Lubricate intermediate shaft thrust plate with petroleum jelly and install plate on shaft pilot hub (Fig. 47).

(4) Check input shaft front seal rings, fiber thrust washer and rear seal ring (Fig. 48). Be sure the ends of rear seal ring are hooked together and diagonal cut ends of front seal rings are firmly seated against each other as shown. Lubricate seal rings with petroleum jelly after checking them.

(5) Assemble front and rear clutches (Fig. 49). Align lugs on front clutch discs. Mount front clutch on rear clutch. Turn front clutch retainer back and forth until front clutch discs are fully seated on rear clutch splined hub.

1 - SHAFT THRUST PLATE 2 - INTERMEDIATE SHAFT PILOT HUB

Fig. 47 Intermediate Shaft Thrust Plate

Fig. 46 Intermediate Shaft And Planetary Geartrain

1 - INTERMEDIATE SHAFT AND PLANETARY GEAR TRAIN ASSEMBLY

Fig. 48 Input Shaft Seal Ring And Thrust Washer

1 - TORLONT FRONT SEAL RINGS 2 - INPUT SHAFT 3 - REAR SEAL RING 4 - THRUST WASHER

Page 41

21 - 170 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

Fig. 49 Assembling Front And Rear Clutches

1 - FRONT CLUTCH ASSEMBLY 2 - REAR CLUTCH ASSEMBLY 3 - REAR CLUTCH SPLINED HUB

(6) Install intermediate shaft thrust washer in hub of rear clutch retainer (Fig. 50). Use petroleum jelly to hold washer in place. Position washer so grooves are facing outward. Washer only fits one way in

clutch retainer hub.

(7) Place transmission case in upright position, or place blocks under front end of transmission repair stand to tilt case rearward. This makes it easier to install front/rear clutch assembly.

(8) Align discs in rear clutch. Then install and engage assembly in front planetary and driving shell (Fig. 51). Turn clutch retainers back and forth until both clutches are seated.

(9) Position front band lever in case and over servo rod guide. Then install front band lever pin in case and slide it through lever.

(10) Coat threads of front band pin access plug with sealer and install it in case. Tighten plug to 17 N·m (13 ft. lbs.) torque.

Fig. 50 Intermediate Shaft Thrust Washer

1 - BE SURE WASHER GROOVES FACE OUT AS SHOWN 2 - REAR CLUTCH RETAINER HUB 3 - SHAFT THRUST WASHER

Fig. 51 Front/Rear Clutch Assemblies

1 - FRONT AND REAR CLUTCH ASSEMBLIES

Page 42

DR AUTOMATIC TRANSMISSION - 48RE 21 - 171

AUTOMATIC TRANSMISSION - 48RE (Continued)

(11) Slide front band over front clutch retainer and install front band strut and anchor (Fig. 52).

(12) Tighten front band adjusting screw until band is tight on clutch retainer. This will hold clutches in place while oil pump is being installed. Verify that

front/rear clutch assembly is still properly seated before tightening band.

(2) Install new oil pump gasket on pilot studs and seat it in case. Be sure gasket is properly aligned with fluid passages in case (Fig. 53).

(3) Coat the reaction shaft thrust washer with petroleum jelly to hold it in place. Then install washer over reaction shaft hub and seat it on pump (Fig. 54).

CAUTION: The thrust washer bore (I.D.), is chamfered on one side. Make sure the chamfered side is installed so it faces the pump.

Fig. 52 Front Band And Linkage

1 - LEVER 2 - STRUT 3 - ANCHOR 4 - FRONT BAND

OIL PUMP

(1) Install oil pump Pilot Studs C-3288-B in case

(Fig. 53).

Fig. 54 Front Clutch Thrust Washer Installation

1 - THRUST WASHER 2 - CHAMFERED SIDE OF WASHER BORE GOES TOWARD PUMP

Fig. 53 Oil Pump Gasket And Pilot Studs

1 - OIL PUMP GASKET 2 - PILOT STUDS C-3288-B

Fig. 55 Reaction Shaft Seal Ring And Thrust Washer

1 - SEAL RINGS 2 - REACTION SHAFT SUPPORT 3 - THRUST WASHER (FIBER)

Page 43

21 - 172 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

(4) Check seal rings on reaction shaft support. Be sure rings are hooked together correctly. Also be sure fiber thrust washer is in position (Fig. 55). Use extra petroleum jelly to hold washer in place if necessary.

(5) Check the torque converter hub seal ring on the reaction shaft for damage. Also check that the seal ring rotates freely in the reaction shaft groove. Replace the seal if necessary.

(6) Lubricate oil pump seals with petroleum Mopart ATF +4.

(7) Mount oil pump on pilot studs and slide pump into case opening (Fig. 56). Work pump into case

by hand. Do not use a mallet or similar tools to seat pump.

(8) Remove pilot studs and install oil pump bolts. Tighten pump bolts alternately and evenly to fully seat pump in case. Then final-tighten pump bolts to 20 N·m (15 ft. lbs.) torque.

(9) Verify correct installation. Rotate input and intermediate shafts and check for bind. If bind exists, components are either mis-assembled, or not seated. Disassemble and correct as necessary before proceeding.

NOTE: If end play is incorrect, transmission is incorrectly assembled, or reaction shaft thrust washer is incorrect. The reaction shaft thrust washer is selective.

(a) Attach Adapter 8266-5 to Handle 8266-8. (b) Attach dial indicator C-3339 to Handle

8266-8.

(c) Install the assembled tool onto the input shaft of the transmission and tighten the retaining screw on Adapter 8266-5 to secure it to the input shaft.

(d) Position the dial indicator plunger against a flat spot on the oil pump and zero the dial indicator.

(e) Move input shaft in and out and record reading. End play should be 0.86 - 2.13 mm (0.034 -

0.084 in.). Adjust as necessary.

Fig. 56 Oil Pump

1 - SEAT OIL PUMP IN CASE BY HAND 2 - REMOVE PILOT STUDS WHEN PUMP IS SEATED

INPUT SHAFT END PLAY CHECK

NOTE: Overdrive unit must be installed in order to correctly measure the input shaft end-play.

(1) Measure input shaft end play (Fig. 57).

Fig. 57 Checking Input Shaft End Play

1 - TOOL 8266-8 2 - TOOL 8266-5 3 - TOOL C-3339

ACCUMULATOR, VALVE BODY, OIL PAN, AND TORQUE CONVERTER

(1) Install accumulator inner spring, piston and

outer spring (Fig. 58).

(2) Verify that the transmission range sensor has

not been installed in case. Valve body can not be installed if sensor is in position.

(3) Install new valve body manual shaft seal in

case (Fig. 59). Lubricate seal lip and manual shaft with petroleum jelly. Start seal over shaft and into case. Seat seal with 15/16 inch, deep well socket.

(4) Install valve body as follows:

Page 44

DR AUTOMATIC TRANSMISSION - 48RE 21 - 173

AUTOMATIC TRANSMISSION - 48RE (Continued)

(a) Start park rod into park pawl. If rod will not slide past park pawl, pawl is engaged in park gear. Rotate overdrive output shaft with suitable size 12 point socket; this will free pawl and allow rod to engage.

(b) Align and seat valve body on case. Be sure manual lever shaft and overdrive connector are fully seated in case.

(c) Install and start all valve body attaching bolts by hand. Then tighten bolts evenly, in a diagonal pattern to 12 N·m (105 in. lbs.) torque. Do

not overtighten valve body bolts. This could result in distortion and cross leakage after installation..

(5) Install new filter on valve body. Tighten filter

screws to 4 N·m (35 in. lbs.).

(6) Move the transmission manual shaft lever to

the manual LOW position.

(7) Install the TRS mounting bracket into the transmission case. Using Adapter 8581 (Fig. 60), tighten the mounting bracket to 34 N·m (300 in.lbs.).

Fig. 60 Tighten the TRS Mounting Bracket

1 - SOLENOID CASE CONNECTOR 2 - TRS MOUNTING BRACKET 3 - ADAPTER 8581

Fig. 58 Accumulator Piston And Springs

1 - ACCUMULATOR PISTON 2 - OUTER SPRING 3 - INNER SPRING

Fig. 59 Manual Lever Shaft Seal

1 - 15/1688 SOCKET 2 - SEAL

(8) Install the TRS (Fig. 61) into the mounting bracket with the wiring connector facing the front of the transmission.

Fig. 61 Remove Transmission Range Sensor

1 - SOLENOID CASE CONNECTOR 2 - TRS MOUNTING BRACKET 3 - TRANSMISSION RANGE SENSOR

CAUTION: If the condition of the transmission before the overhaul procedure caused excessive metallic or fiber contamination in the fluid, replace the torque converter and reverse flush the cooler(s) and cooler lines. Fluid contamination and transmission failure can result if not done.

Page 45

21 - 174 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

(9) Install the two screws to hold the TRS to the mounting bracket. Tighten the screws to 5 N·m (45 in.lbs.).

(10) Verify proper sensor operation (Fig. 62).

Fig. 62 Transmission Range Sensor Operation

1 - NEUTRAL CONTACT 2 - MANUAL LEVER AND SENSOR PLUNGER IN REVERSE POSITION 3 - PARK CONTACT 4 - TRANSMISSION RANGE SENSOR

burrs, scratches, or nicks. Polish the hub and notches with 320/400 grit paper and crocus cloth if necessary. The hub must be smooth to avoid damaging pump seal at installation.

(2) Lubricate pocket in the rear oil pump seal lip

with transmission fluid.

(3) Lubricate converter pilot hub of the crankshaft

with a light coating of Mopart High Temp Grease.

(4) Align and install converter in oil pump.

(5) Carefully insert converter in oil pump. Then rotate converter back and forth until fully seated in pump gears.

(6) Check converter seating with steel scale and straightedge (Fig. 63). Surface of converter lugs should be 19mm (0.75 in.) to rear of straightedge when converter is fully seated.

(7) Temporarily secure converter with C-clamp.

(11) Move the transmission manual shaft lever to

the PARK position.

(12) Install torque converter. Use C-clamp or metal

strap to hold converter in place for installation.

BAND ADJUSTMENT AND FINAL

(1) Adjust front and rear bands as follows:

(a) Loosen locknut on each band adjusting screw

4-5 turns.

(b) Tighten both adjusting screws to 8 N·m (72

in. lbs.).

turns.

(d) Back off rear band adjusting screw 3 turns.

(e) Hold each adjusting screw in position and tighten locknut to 34 N·m (25 ft. lbs.) torque. (2) Install magnet in oil pan. Magnet seats on

small protrusion at corner of pan.

(3) Position new oil pan gasket on case and install

oil pan. Tighten pan bolts to 13.6 N·m (125 in. lbs.).

(4) Install throttle valve and shift selector levers

on valve body manual lever shaft.

(5) Apply small quantity of dielectric grease to ter-

minal pins of solenoid case connector and neutral switch.

(6) Fill transmission with recommended fluid.

INSTALLATION

(1) Check torque converter hub inner and outer

diameters and hub drive notches for sharp edges

Fig. 63 Checking Converter Seating - Typical

1 - SCALE 2 - STRAIGHTEDGE

(8) Position transmission on jack and secure it

with chains.

(9) Check condition of converter driveplate.

Replace the plate if cracked, distorted or damaged.

Also be sure transmission dowel pins are seated in engine block and protrude far enough to hold transmission in alignment.

(10) Raise transmission and align converter with

drive plate and converter housing with engine block.

(11) Move transmission forward. Then raise, lower or tilt transmission to align converter housing with engine block dowels.

(12) Carefully work transmission forward and over engine block dowels until converter hub is seated in crankshaft.

Page 46

DR AUTOMATIC TRANSMISSION - 48RE 21 - 175

AUTOMATIC TRANSMISSION - 48RE (Continued)

(13) Install bolts attaching converter housing to

engine.

(14) Install rear support. (15) Install the rear transmission crossmember.

(16) Lower transmission onto crossmember and install bolts attaching transmission mount to crossmember.

(17) Remove engine support fixture.

(18) Install the transfer case, if equipped.

(19) Install crankshaft position sensor. (Refer to 14

- FUEL SYSTEM/FUEL INJECTION/CRANKSHAFT POSITION SENSOR - INSTALLATION)

(20) Connect gearshift cable (Fig. 64) and throttle cable to transmission.

(22) Install torque converter-to-driveplate bolts. (23) Install converter housing access cover.

(24) Install starter motor and cooler line bracket. (Refer to 8 - ELECTRICAL/STARTING/STARTER MOTOR - INSTALLATION)

(25) Connect cooler lines (Fig. 65) to transmission.

Fig. 65 Transmission Cooler Lines

1 - TRANSMISSION 2 - RADIATOR 3 - COOLER LINES

Fig. 64 Gearshift Cable At Transmission

1 - GEARSHIFT CABLE 2 - TRANSMISSION MANUAL LEVER 3 - CABLE SUPPORT BRACKET

(21) Connect wires to the transmission range sensor and transmission solenoid connector. Be sure the transmission harnesses are properly routed.

CAUTION: It is essential that correct length bolts be used to attach the converter to the driveplate. Bolts that are too long will damage the clutch surface inside the converter.

(26) Install transmission fill tube. Install new seal

on tube before installation.

(27) Install any exhaust components previously

removed.

(28) Align and connect propeller shaft. (Refer to 3 DIFFERENTIAL & DRIVELINE/PROPELLER SHAFT/PROPELLER SHAFT - INSTALLATION)

(29) Adjust gearshift cable and throttle valve cable, if necessary.

(30) Install the transfer case skid plate, if equipped.

(31) Lower vehicle.

(32) Fill transmission with Mopart ATF +4, Automatic Transmission fluid.

Page 47

21 - 176 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

SCHEMATICS AND DIAGRAMS

HYDRAULIC SCHEMATICS

HYDRAULIC FLOW IN PARK

Page 48

DR AUTOMATIC TRANSMISSION - 48RE 21 - 177

AUTOMATIC TRANSMISSION - 48RE (Continued)

HYDRAULIC FLOW IN NEUTRAL

Page 49

21 - 178 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

HYDRAULIC FLOW IN REVERSE

Page 50

DR AUTOMATIC TRANSMISSION - 48RE 21 - 179

AUTOMATIC TRANSMISSION - 48RE (Continued)

HYDRAULIC FLOW IN DRIVE FIRST GEAR

Page 51

21 - 180 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

HYDRAULIC FLOW IN DRIVE SECOND GEAR (CONVERTER CLUTCH NOT APPLIED)

Page 52

DR AUTOMATIC TRANSMISSION - 48RE 21 - 181

AUTOMATIC TRANSMISSION - 48RE (Continued)

HYDRAULIC FLOW IN DRIVE SECOND GEAR (CONVERTER CLUTCH APPLIED)

Page 53

21 - 182 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

HYDRAULIC FLOW IN DRIVE THIRD GEAR (CONVERTER CLUTCH NOT APPLIED)

Page 54

DR AUTOMATIC TRANSMISSION - 48RE 21 - 183

AUTOMATIC TRANSMISSION - 48RE (Continued)

HYDRAULIC FLOW IN DRIVE THIRD GEAR (CONVERTER CLUTCH APPLIED)

Page 55

21 - 184 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

HYDRAULIC FLOW IN DRIVE FOURTH GEAR (CONVERTER CLUTCH NOT APPLIED)

Page 56

DR AUTOMATIC TRANSMISSION - 48RE 21 - 185

AUTOMATIC TRANSMISSION - 48RE (Continued)

HYDRAULIC FLOW IN DRIVE FOURTH GEAR (CONVERTER CLUTCH APPLIED)

Page 57

21 - 186 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

HYDRAULIC FLOW IN MANUAL LOW (1)

Page 58

DR AUTOMATIC TRANSMISSION - 48RE 21 - 187

AUTOMATIC TRANSMISSION - 48RE (Continued)

HYDRAULIC FLOW IN MANUAL SECOND (2)

Page 59

21 - 188 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

HYDRAULIC FLOW DURING FULL THROTTLE 3-2 DOWNSHIFT (PASSING GEAR)

Page 60

DR AUTOMATIC TRANSMISSION - 48RE 21 - 189

AUTOMATIC TRANSMISSION - 48RE (Continued)

SPECIFICATIONS

TRANSMISSION

GENERAL

Component Metric Inch

Planetary end play 0.150-1.22mm0.006-0.048

Input shaft end play 0.86-2.13

Clutch pack clearance/

Front.

Clutch pack clearance/

2.5-4.09 mm

0.635-0.914mm0.025-0.036

Rear.

Front clutch 5 discs

Rear clutch 4 discs

Overdrive clutch 5(STD) OR 6(Diesel HO)

Direct clutch 23 Single Sided discs

Band adjustment from

72 in. lbs.

Front band Back off 1 3/4 turns

Rear band Back off 3 turns

Recommended fluid MoparT ATF +4

0.034-0.084

0.098-0.161

discs

in.

GEAR RATIOS

1ST GEAR 2.45:1 2ND GEAR 1.45:1 3RD GEAR 1.0:1

4TH GEAR 0.69:1

REVERSE 2.20:1

THRUST WASHER/SPACER/SNAP-RING DIMENSIONS

Component Metric Inch

Front clutch thrust washer (reaction shaft support hub) 1.55 mm 0.061 in.

2.15 mm 0.084 in.

2.59 mm 0.102 in.

Rear clutch thrust washer (clutch retainer) 1.55 mm 0.061 in.

Intermediate shaft thrust plate (shaft hub pilot) 1.5-1.6 mm 0.060-0.063 in.

Output shaft thrust washer (rear clutch hub) 1.3-1.4 mm 0.052-0.054 in.

1.75-1.8 mm 0.068-0.070 in.

2.1-2.2 mm 0.083-0.085 in.

Rear clutch pack snap-ring 1.5-1.6 mm 0.060-0.062 in.

1.9-1.95 mm 0.074-0.076 in.

Planetary geartrain snap-ring (at front of output shaft) 1.4-1.5 mm 0.055-0.059 in.

1.6-1.7 mm 0.062-0.066 in.

Overdrive piston thrust plate Thrust plate and

Intermediate shaft spacer

spacer are select fit.

Refer to size charts

and selection

procedures in

Overdrive Unit D&A

procedures

Page 61

21 - 190 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

PRESSURE TEST

Overdrive clutch Fourth gear only Pressure should be 524-565 kPa (76-82 psi) with

closed throttle and increase to 965 kPa (140 psi) at 1/2

to 3/4 throttle.

Line pressure (at

accumulator)

Front servo Third or Fourth gear only No more than 21 kPa (3 psi) lower than line pressure.

Rear servo 1 range No more than 21 kPa (3 psi) lower than line pressure.

Governor D range closed throttle Pressure should respond smoothly to changes in mph

Closed throttle 372-414 kPa (54-60 psi).

R range 1103 kPa (160 psi) at idle, builds to 1862 kPa (270 psi)

at 1600 rpm.

and return to 0-7 kPa (0-1.5 psi) when stopped with

transmission in D, 1, 2. Pressure above 7 kPa (1.5 psi)

at stand still will prevent transmission from

downshifting.

TORQUE SPECIFICATIONS

DESCRIPTION N·m Ft. Lbs. In. Lbs.

Fitting, cooler line at trans 18 13 -

Bolt, torque convertor 47 35 -

Bolt, clevis bracket to crossmember 47 35 -

Bolt, clevis bracket to rear support 68 50 -

Bolt, driveplate to crankshaft 75 55 -

Plug, front band reaction 17 13 -

Locknut, front band adj. 34 25 -

Bolt, fluid pan 13.6 - 120

Screws, fluid filter 4 - 35

Bolt, oil pump 20 15 -

Bolt, overrunning clutch cam 17 13 -

Bolt, O/D to trans. 34 25 -

Bolt, O/D piston retainer 17 13 -

Plug, pressure test port 14 10 -

Bolt, reaction shaft support 20 15 -

Locknut, rear band 41 30 -

Bolt, valve body to case 12 - 100

Sensor, trans speed 27 20 -

Screw, solenoid wiring connector 4 - 35

Screw, solenoid to transfer plate 4 - 35 Bracket, transmission range sensor mounting 34 25 Screw, transmision range sensor to mounting

bracket

5-45

Page 62

DR AUTOMATIC TRANSMISSION - 48RE 21 - 191

AUTOMATIC TRANSMISSION - 48RE (Continued)

SPECIAL TOOLS

RE TRANSMISSION

Adapter, Band Adjuster - C-3705

Pilot Studs C-3288-B

Puller/Slide Hammer, C-3752

Oil Pressure Gauge - C-3292

Pressure Gauge - C-3293SP

Dial Indicator C-3339

Gauge, Throttle Setting - C-3763

Installer C-3860-A

Valve Spring Compressor C-3422-B

Spring Compressor - C-3863-A

Page 63

21 - 192 AUTOMATIC TRANSMISSION - 48RE DR

AUTOMATIC TRANSMISSION - 48RE (Continued)

Retainer - 6583

Handle C-4171

Installer - 8114

Dial Caliper - C-4962

Spring Compressor and Alignment Shaft - 6227

Gauge Bar - 6311

Socket, TRS Mounting Bracket - 8581

Installer, Seal - 9037

Gauge - 6312

Page 64

DR AUTOMATIC TRANSMISSION - 48RE 21 - 193

ACCUMULATOR

DESCRIPTION

The accumulator (Fig. 66) is a hydraulic device that has the sole purpose of cushioning the application of a band or clutch. The accumulator consists of a dual-land piston and a spring located in a bore in the transmission case. The 3-4 accumulator is located in a housing attached to the side of the valve body (Fig. 67).

Fig. 66 Accumulator

1 - ACCUMULATOR PISTON 2 - PISTON SPRING

OPERATION

Both the accumulator and the 3-4 accumulator function the same. Line pressure is directed to the small end of the piston when the transmission is placed into a DRIVE position (Fig. 68), bottoming it against the accumulator plate. When the 1-2 upshift occurs (Fig. 69), line pressure is directed to the large end of the piston and then to the kickdown servo. As the line pressure reaches the accumulator, the combination of spring pressure and line pressure forces the piston away from the accumulator plate. This causes a balanced pressure situation, which results in a cushioned band application. After the kickdown servo has become immovable, line pressure will finish pushing the accumulator up into its bore. When the large end of the accumulator piston is seated in its bore, the band or clutch is fully applied.

NOTE: The accumulator is shown in the inverted position for illustrative purposes.

Fig. 67 3-4 Accumulator and Housing

1 - ACCUMULATOR PISTON 2 - 3-4 ACCUMULATOR HOUSING 3 - TEFLON SEALS 4 - PISTON SPRING 5 - COVER PLATE AND SCREWS

Fig. 68 Accumulator in DRIVE - FIRST Gear Position

1 - LINE PRESSURE

Page 65

21 - 194 AUTOMATIC TRANSMISSION - 48RE DR

ACCUMULATOR (Continued)

Fig. 70 Front Band

1 - FRONT BAND 2 - TRANSMISSION HOUSING

band design (the drum is completely encompassed/ wrapped by the band). The double-wrap band pro-

Fig. 69 Accumulator in SECOND Gear Position

1 - BOTTOM OF BORE 2 - LINE PRESSURE 3 - SHUTTLE VALVE

vides a greater holding power in comparison to the single-wrap design.

INSPECTION

Inspect the accumulator piston and seal rings. Replace the seal rings if worn or cut. Replace the piston if chipped or cracked.

Check condition of the accumulator inner and outer springs. Replace the springs if the coils are cracked, distorted or collapsed.

BANDS

DESCRIPTION

KICKDOWN (FRONT) BAND

The kickdown, or “front”, band (Fig. 70) holds the common sun gear of the planetary gear sets. The front (kickdown) band is made of steel, and faced on its inner circumference with a friction-type lining. One end of the band is anchored to the transmission case, and the other is acted on with a pushing force by a servo piston. The front band is a single-wrap design (the band does not completely encompass/ wrap the drum that it holds).

LOW/REVERSE (REAR) BAND

The low/reverse band, or “rear”, band (Fig. 71) is similar in appearance and operation to the front band. The rear band is slightly different in that it does not use a link bar, but is acted directly on by the apply lever. This is referred to as a double-wrap

Fig. 71 Rear Band

1 - ADJUSTING SCREW 2 - LOCKNUT 3 - LEVER 4 - REAR BAND 5 - REACTION PIN 6 - O-RINGS 7 - PIVOT PIN

OPERATION

KICKDOWN (FRONT) BAND

The kickdown band holds the common sun gear of the planetary gear sets by applying and holding the front clutch retainer, which is splined to the sun gear driving shell, and in turn splined directly to the sun gear. The application of the band by the servo is typically done by an apply lever and link bar.

Page 66

DR AUTOMATIC TRANSMISSION - 48RE 21 - 195

BANDS (Continued)

LOW/REVERSE (REAR) BAND

The rear band holds the rear planet carrier stationary by being mounted around and applied to the low/reverse drum.

ADJUSTMENTS

ADJUSTMENT - BANDS

FRONT BAND

The front (kickdown) band adjusting screw is located on the left side of the transmission case above the manual valve and throttle valve levers.

(1) Raise vehicle.

(2) Loosen band adjusting screw locknut (Fig. 72). Then back locknut off 3-5 turns. Be sure adjusting screw turns freely in case. Apply lubricant to screw threads if necessary.

(3) Tighten band adjusting screw to 8 N·m (72 in. lbs.) torque with an appropriate Torx™ socket.

CAUTION: If Adapter C-3705 is needed to reach the adjusting screw, tighten the screw to only 5 N·m (47-50 in. lbs.) torque.

REAR BAND

The transmission oil pan must be removed for

access to the rear band adjusting screw.

(1) Raise vehicle. (2) Remove transmission oil pan and drain fluid. (3) Loosen band adjusting screw locknut 5-6 turns.

Be sure adjusting screw turns freely in lever.

(4) Tighten adjusting screw to 8 N·m (72 in. lbs.)

torque (Fig. 73).

(5) Back off adjusting screw 3 turns. (6) Hold adjusting screw in place and tighten lock-

nut to 34 N·m (25 ft. lbs.) torque.

(7) Position new gasket on oil pan and install pan on transmission. Tighten pan bolts to 17 N·m (13 ft. lbs.) torque.

(8) Lower vehicle and refill transmission with Mopart ATF +4, Automatic Transmission fluid.

(4) Back off front band adjusting screw 1-3/4

turns.

(5) Hold adjuster screw in position and tighten

locknut to 41 N·m (30 ft. lbs.) torque.

(6) Lower vehicle.

Fig. 72 Front Band Adjustment Screw Location

1 - LOCK-NUT 2 - FRONT BAND ADJUSTER

Fig. 73 Rear Band Adjustment Screw Location

1 - LOW-REVERSE BAND ADJUSTMENT

Page 67

21 - 196 AUTOMATIC TRANSMISSION - 48RE DR

BRAKE TRANSMISSION SHIFT INTERLOCK SYSTEM

DESCRIPTION

The Brake Transmission Shifter Interlock (BTSI) (Fig. 74), is a solenoid operated system. It consists of a solenoid permanently mounted on the gearshift cable.

LOCK. When the shifter is in any other gear or neutral position, the ignition key cylinder should not rotate to the LOCK position.

(3) Shifting out of PARK should not be possible when the ignition key cylinder is in the OFF position.

(4) Shifting out of PARK should not be possible while applying normal pushbutton force and ignition key cylinder is in the RUN or START positions unless the foot brake pedal is depressed approximately 1/2 inch (12mm).

(5) Shifting out of PARK should not be possible when the ignition key cylinder is in the ACCESSORY or LOCK positions.

(6) Shifting between any gears, NEUTRAL or into PARK may be done without depressing foot brake pedal with ignition switch in RUN or START positions.

ADJUSTMENTS - BRAKE TRANSMISSION SHIFT INTERLOCK

Correct cable adjustment is important to proper interlock operation. The gearshift cable must be correctly adjusted in order to shift out of PARK.

Fig. 74 Brake Transmission Interlock Mechanism

1 - STEERING COLUMN 2 - GEARSHIFT CABLE 3 - GEARSHIFT CABLE LOCK TAB 4 - BTSI SOLENOID LOCK TAB 5 - BTSI CONNECTOR

OPERATION

The system locks the shifter into the PARK position. The interlock system is engaged whenever the ignition switch is in the LOCK or ACCESSORY position. An additional electrically activated feature will prevent shifting out of the PARK position unless the brake pedal is depressed approximately one-half an inch. A magnetic holding device in line with the park lock cable is energized when the ignition is in the RUN position. When the key is in the RUN position and the brake pedal is depressed, the shifter is unlocked and will move into any position. The interlock system also prevents the ignition switch from being turned to the LOCK or ACCESSORY position, unless the shifter is fully locked into the PARK position.

DIAGNOSIS AND TESTING - BRAKE TRANSMISSION SHIFT INTERLOCK

(1) Verify that the key can only be removed in the PARK position

(2) When the shift lever is in PARK And the shift handle pushbutton is in the “OUT” position, the ignition key cylinder should rotate freely from OFF to

ADJUSTMENT PROCEDURE

(1) Remove the steering column trim as necessary

for access to the brake transmission shift interlock.

(2) Shift the transmission into the PARK position. (3) Pull upward on both the BTSI lock tab and the

gearshift cable lock tab (Fig. 75).

(4) Verify that the shift lever is in the PARK posi-

tion.

(5) Verify positive engagement of the transmission park lock by attempting to rotate the propeller shaft. The shaft will not rotate when the park lock is engaged.

(6) Turn ignition switch to LOCK position. Be

sure ignition key cylinder is in the LOCK position. Cable will not adjust correctly in any other position.

(7) Ensure that the cable is free to self-adjust by pushing cable rearward and releasing.

(8) Push the gearshift cable lock tab down until it snaps in place.

(9) Locate the BTSI alignment hole in the bottom of the BTSI mechanism between the BTSI lock tab and the BTSI connector.

(10) Move the BTSI assembly up or down on the gearshift cable until an appropriate size drill bit can be inserted into the alignment hole and through the assembly.

(11) Push the BTSI lock tab down until it snaps into place and remove the drill bit.

(12) Install any steering column trim previously removed.

Page 68

DR AUTOMATIC TRANSMISSION - 48RE 21 - 197

BRAKE TRANSMISSION SHIFT INTERLOCK SYSTEM (Continued)

• PARK position - Apply downward force on the shift arm and remove pressure. Engine starts must be possible.

• NEUTRAL position - Normal position. Engine starts must be possible.

• NEUTRAL position - Engine running and brakes applied, apply upward force on the shift arm. Transmission shall not be able to shift from neutral to reverse.

ELECTRONIC GOVERNOR

DESCRIPTION

Governor pressure is controlled electronically. Com-

ponents used for governor pressure control include:

Fig. 75 Brake Transmission Interlock Mechanism

1 - STEERING COLUMN 2 - GEARSHIFT CABLE 3 - GEARSHIFT CABLE LOCK TAB 4 - BTSI SOLENOID LOCK TAB 5 - BTSI CONNECTOR

BTSI FUNCTION CHECK

(1) Verify removal of ignition key allowed in PARK

position only.

(2) When the shift lever is in PARK, the ignition key cylinder should rotate freely from off to lock. When the shifter is in any other position, the ignition key should not rotate from off to lock.

(3) Shifting out of PARK should be possible when the ignition key cylinder is in the off position.

(4) Shifting out of PARK should not be possible while applying normal force, and ignition key cylinder is in the run or start positions, unless the foot brake pedal is depressed approximately 1/2 inch (12mm).

(5) Shifting out of PARK should not be possible when the ignition key cylinder is in the accessory or lock position.

(6) Shifting between any gear and NEUTRAL, or PARK, may be done without depressing foot brake with ignition switch in run or start positions.

(7) Engine starts must be possible with shifter lever in PARK or NEUTRAL positions only. Engine starts must not be possible in any position other than PARK or NEUTRAL.

(8) With shifter lever in the:

• PARK position - Apply upward force on the shift arm and remove pressure. Engine starts must be possible.

• Governor body

• Valve body transfer plate

• Governor pressure solenoid valve

• Governor pressure sensor

• Fluid temperature thermistor

• Throttle position sensor (TPS)

• Transmission speed sensor

• Powertrain control module (PCM)

GOVERNOR PRESSURE SOLENOID VALVE

The solenoid valve is a duty-cycle solenoid which regulates the governor pressure needed for upshifts and downshifts. It is an electro-hydraulic device located in the governor body on the valve body transfer plate (Fig. 76).

Fig. 76 Governor Pressure Solenoid Valve

1 - SOLENOID FILTER 2 - GOVERNOR PRESSURE SOLENOID

Page 69

21 - 198 AUTOMATIC TRANSMISSION - 48RE DR

ELECTRONIC GOVERNOR (Continued)

GOVERNOR PRESSURE SENSOR

The governor pressure sensor measures output

pressure of the governor pressure solenoid valve (Fig.

77).

Fig. 77 Governor Pressure Sensor

1 - GOVERNOR BODY 2 - GOVERNOR PRESSURE SENSOR/TRANSMISSION FLUID TEMPERATURE THERMISTOR

GOVERNOR BODY AND TRANSFER PLATE

The transfer plate is designed to supply transmission line pressure to the governor pressure solenoid valve and to return governor pressure.

The governor pressure solenoid valve is mounted in the governor body. The body is bolted to the lower side of the transfer plate (Fig. 77).

GOVERNOR PRESSURE CURVES

There are four governor pressure curves programmed into the transmission control module. The different curves allow the control module to adjust governor pressure for varying conditions. One curve is used for operation when fluid temperature is at, or below, –1°C (30°F). A second curve is used when fluid temperature is at, or above, 10°C (50°F) during normal city or highway driving. A third curve is used during wide-open throttle operation. The fourth curve is used when driving with the transfer case in low range.

OPERATION

Compensation is required for performance variations of two of the input devices. Though the slope of the transfer functions is tightly controlled, offset may vary due to various environmental factors or manufacturing tolerances.

The pressure transducer is affected by barometric pressure as well as temperature. Calibration of the zero pressure offset is required to compensate for shifting output due to these factors.

Normal calibration will be performed when sump temperature is above 50 degrees F, or in the absence

of sump temperature data, after the first 10 minutes of vehicle operation. Calibration of the pressure transducer offset occurs each time the output shaft speed falls below 200 RPM. Calibration shall be repeated each 3 seconds the output shaft speed is below 200 RPM. A 0.5 second pulse of 95% duty cycle is applied to the governor pressure solenoid valve and the transducer output is read during this pulse. Averaging of the transducer signal is necessary to reject electrical noise.

Under cold conditions (below 50 degrees F sump), the governor pressure solenoid valve response may be too slow to guarantee 0 psi during the 0.5 second calibration pulse. Calibration pulses are continued during this period, however the transducer output valves are discarded. Transducer offset must be read at key-on, under conditions which promote a stable reading. This value is retained and becomes the offset during the 9cold9 period of operation.

GOVERNOR PRESSURE SOLENOID VALVE

The inlet side of the solenoid valve is exposed to normal transmission line pressure. The outlet side of the valve leads to the valve body governor circuit.

The solenoid valve regulates line pressure to produce governor pressure. The average current supplied to the solenoid controls governor pressure. One amp current produces zero kPa/psi governor pressure. Zero amps sets the maximum governor pressure.

The powertrain control module (PCM) turns on the trans control relay which supplies electrical power to the solenoid valve. Operating voltage is 12 volts (DC). The PCM controls the ground side of the solenoid using the governor pressure solenoid control circuit.

GOVERNOR PRESSURE SENSOR

The sensor output signal provides the necessary feedback to the PCM. This feedback is needed to adequately control governor pressure.

GOVERNOR BODY AND TRANSFER PLATE

The transfer plate channels line pressure to the solenoid valve through the governor body. It also channels governor pressure from the solenoid valve to the governor circuit. It is the solenoid valve that develops the necessary governor pressure.

GOVERNOR PRESSURE CURVES

LOW TRANSMISSION FLUID TEMPERATURE

When the transmission fluid is cold the conventional governor can delay shifts, resulting in higher than normal shift speeds and harsh shifts. The electronically controlled low temperature governor pres-

Page 70

DR AUTOMATIC TRANSMISSION - 48RE 21 - 199

ELECTRONIC GOVERNOR (Continued)

sure curve is higher than normal to make the transmission shift at normal speeds and sooner. The PCM uses a temperature sensor in the transmission oil sump to determine when low temperature governor pressure is needed.

NORMAL OPERATION

Normal operation is refined through the increased computing power of the PCM and through access to data on engine operating conditions provided by the PCM that were not available with the previous stand-alone electronic module. This facilitated the development of a load adaptive shift strategy - the ability to alter the shift schedule in response to vehicle load condition. One manifestation of this capability is grade 9hunting9 prevention - the ability of the transmission logic to delay an upshift on a grade if the engine does not have sufficient power to maintain speed in the higher gear. The 3-2 downshift and the potential for hunting between gears occurs with a heavily loaded vehicle or on steep grades. When hunting occurs, it is very objectionable because shifts are frequent and accompanied by large changes in noise and acceleration.

WIDE OPEN THROTTLE OPERATION

In wide-open throttle (WOT) mode, adaptive memory in the PCM assures that up-shifts occur at the preprogrammed optimum speed. WOT operation is determined from the throttle position sensor, which is also a part of the emission control system. The initial setting for the WOT upshift is below the optimum engine speed. As WOT shifts are repeated, the PCM learns the time required to complete the shifts by comparing the engine speed when the shifts occur to the optimum speed. After each shift, the PCM adjusts the shift point until the optimum speed is reached. The PCM also considers vehicle loading, grade and engine performance changes due to high altitude in determining when to make WOT shifts. It does this by measuring vehicle and engine acceleration and then factoring in the shift time.

REMOVAL

(1) Hoist and support vehicle on safety stands. (2) Remove transmission fluid pan and filter. (3) Disengage wire connectors from pressure sen-

sor and solenoid (Fig. 78).

Fig. 78 Governor Solenoid And Pressure Sensor

1 - PRESSURE SENSOR 2 - PRESSURE SOLENOID 3 - GOVERNOR

(4) Remove screws holding pressure solenoid

retainer to governor body.

(5) Separate solenoid retainer from governor (Fig.

79).

TRANSFER CASE LOW RANGE OPERATION

On four-wheel drive vehicles operating in low range, the engine can accelerate to its peak more rapidly than in Normal range, resulting in delayed shifts and undesirable engine 9flare.9 The low range governor pressure curve is also higher than normal to initiate upshifts sooner. The PCM compares electronic vehicle speed signal used by the speedometer to the transmission output shaft speed signal to determine when the transfer case is in low range.

Fig. 79 Pressure Solenoid Retainer

1 - PRESSURE SOLENOID RETAINER 2 - GOVERNOR

Page 71

21 - 200 AUTOMATIC TRANSMISSION - 48RE DR

ELECTRONIC GOVERNOR (Continued)

(6) Pull solenoid from governor body (Fig. 80).

(7) Pull pressure sensor from governor body.

(8) Remove bolts holding governor body to valve body.

Fig. 80 Pressure Solenoid and O-ring

1 - PRESSURE SOLENOID 2 - O-RING 3 - GOVERNOR

(9) Separate governor body from valve body (Fig.

81).

(10) Remove governor body gasket.

(2) Place governor body in position on valve body. (3) Install bolts to hold governor body to valve

body.

Fig. 82 Governor Body and Gasket

1 - GOVERNOR BODY 2 - GASKET

(4) Lubricate o-ring on pressure sensor with trans-

mission fluid.

(5) Align pressure sensor to bore in governor body. (6) Push pressure sensor into governor body. (7) Lubricate o-ring, on pressure solenoid, with

transmission fluid.

(8) Align pressure solenoid to bore in governor

body (Fig. 83).

(9) Push solenoid into governor body.

Fig. 81 Governor Body and Gasket

1 - GOVERNOR BODY 2 - GASKET

INSTALLATION

Before installing the pressure sensor and solenoid in the governor body, replace o-ring seals, clean the gasket surfaces and replace gasket.

(1) Place gasket in position on back of governor body (Fig. 82).

Fig. 83 Pressure Solenoid and O-ring

1 - PRESSURE SOLENOID 2 - O-RING 3 - GOVERNOR

Page 72

DR AUTOMATIC TRANSMISSION - 48RE 21 - 201

ELECTRONIC GOVERNOR (Continued)

(10) Place solenoid retainer in position on governor (Fig. 84).

(11) Install screws to hold pressure solenoid retainer to governor body.

Fig. 84 Pressure Solenoid Retainer

1 - PRESSURE SOLENOID RETAINER 2 - GOVERNOR

(12) Engage wire connectors into pressure sensor and solenoid (Fig. 85).

(13) Install transmission fluid pan and (new) filter.

(14) Lower vehicle and road test to verify repair.

(4) Remove old seal with a screw mounted in a

slide hammer.

INSTALLATION

(1) Place seal in position on overdrive housing. (2) Drive seal into overdrive housing with Seal

Installer 9037 (Fig. 86).

(3) Carefully guide propeller shaft slip yoke into housing and onto output shaft splines. Align marks made at removal and connect propeller shaft to rear axle pinion yoke.

Fig. 86 Installing Overdrive Housing Yoke Seal

1 - SPECIAL TOOL 9037 2 - SPECIAL TOOL C-4171

FLUID AND FILTER

Fig. 85 Governor Solenoid And Pressure Sensor

1 - PRESSURE SENSOR 2 - PRESSURE SOLENOID 3 - GOVERNOR

EXTENSION HOUSING SEAL

REMOVAL

(1) Raise vehicle. (2) Mark propeller shaft and axle yoke for align-

ment reference.

(3) Disconnect and remove propeller shaft.

DIAGNOSIS AND TESTING

DIAGNOSIS AND TESTING - EFFECTS OF INCORRECT FLUID LEVEL

A low fluid level allows the pump to take in air along with the fluid. Air in the fluid will cause fluid pressures to be low and develop slower than normal. If the transmission is overfilled, the gears churn the fluid into foam. This aerates the fluid and causing the same conditions occurring with a low level. In either case, air bubbles cause fluid overheating, oxidation and varnish buildup which interferes with valve and clutch operation. Foaming also causes fluid expansion which can result in fluid overflow from the transmission vent or fill tube. Fluid overflow can easily be mistaken for a leak if inspection is not careful.

DIAGNOSIS AND TESTING - CAUSES OF BURNT FLUID

Burnt, discolored fluid is a result of overheating which has two primary causes.

(1) A result of restricted fluid flow through the main and/or auxiliary cooler. This condition is usually the result of a faulty or improperly installed drainback valve, a damaged main cooler, or severe restrictions in the coolers and lines caused by debris or kinked lines.

Page 73

21 - 202 AUTOMATIC TRANSMISSION - 48RE DR

FLUID AND FILTER (Continued)

(2) Heavy duty operation with a vehicle not properly equipped for this type of operation. Trailer towing or similar high load operation will overheat the transmission fluid if the vehicle is improperly equipped. Such vehicles should have an auxiliary transmission fluid cooler, a heavy duty cooling system, and the engine/axle ratio combination needed to handle heavy loads.

DIAGNOSIS AND TESTING - FLUID CONTAMINATION

Transmission fluid contamination is generally a result of:

• adding incorrect fluid

• failure to clean dipstick and fill tube when

checking level

• engine coolant entering the fluid

• internal failure that generates debris

• overheat that generates sludge (fluid break-

down)

• failure to replace contaminated converter after

repair

The use of non-recommended fluids can result in transmission failure. The usual results are erratic shifts, slippage, abnormal wear and eventual failure due to fluid breakdown and sludge formation. Avoid this condition by using recommended fluids only.

The dipstick cap and fill tube should be wiped clean before checking fluid level. Dirt, grease and other foreign material on the cap and tube could fall into the tube if not removed beforehand. Take the time to wipe the cap and tube clean before withdrawing the dipstick.

Engine coolant in the transmission fluid is generally caused by a cooler malfunction. The only remedy is to replace the radiator as the cooler in the radiator is not a serviceable part. If coolant has circulated through the transmission, an overhaul is necessary.

The torque converter should also be replaced whenever a failure generates sludge and debris. This is necessary because normal converter flushing procedures will not remove all contaminants.

geartrain churns up foam and cause the same conditions which occur with a low fluid level.

In either case, air bubbles can cause overheating and/or fluid oxidation, and varnishing. This can interfere with normal valve, clutch, and accumulator operation. Foaming can also result in fluid escaping from the transmission vent where it may be mistaken for a leak.

After the fluid has been checked, seat the dipstick fully to seal out water and dirt.

The transmission has a dipstick to check oil level. It is located on the right side of the engine. Be sure to wipe all dirt from dipstick handle before removing.

Fluid level is checked with the engine running at curb idle speed, the transmission in NEUTRAL and the transmission fluid at normal operating temperature. The engine should be running at idle

speed for at least one minute, with the vehicle on level ground.

The transmission fluid level can be checked two ways.

PROCEDURE ONE

(1) Transmission fluid must be at normal operating temperature for accurate fluid level check. Drive vehicle if necessary to bring fluid temperature up to normal hot operating temperature of 82°C (180°F).

(2) Position vehicle on level surface.

(3) Start and run engine at curb idle speed.

(4) Apply parking brakes.

(5) Shift transmission momentarily into all gear ranges. Then shift transmission back to NEUTRAL.

(6) Clean top of filler tube and dipstick to keep dirt from entering tube.

(7) Remove dipstick (Fig. 87) and check fluid level as follows:

(a) Correct acceptable level is in crosshatch area. (b) Correct maximum level is to MAX arrow

mark.

+4 to restore correct level. Do not overfill.

STANDARD PROCEDURE

STANDARD PROCEDURE - FLUID LEVEL CHECK

Low fluid level can cause a variety of conditions because it allows the pump to take in air along with the fluid. As in any hydraulic system, air bubbles make the fluid spongy, therefore, pressures will be low and build up slowly.

Improper filling can also raise the fluid level too high. When the transmssion has too much fluid, the

Fig. 87 Dipstick Fluid Level Marks - Typical

1 - DIPSTICK 2 - MAXIMUM CORRECT FLUID LEVEL 3 - ACCEPTABLE FLUID LEVEL

Page 74

DR AUTOMATIC TRANSMISSION - 48RE 21 - 203

FLUID AND FILTER (Continued)

PROCEDURE TWO

(1) Start engine and apply parking brake.

(2) Shift the transmission into DRIVE for approximately 2 seconds.

(3) Shift the transmission into REVERSE for approximately 2 seconds.

(4) Shift the transmission into PARK.

(5) Hook up DRBt scan tool and select engine.

(6) Select sensors.

(7) Read the transmission temperature value.

(8) Compare the fluid temperature value with the chart.

(9) Adjust transmission fluid level shown on the dipstick according to the chart (Fig. 88).

NOTE: After adding any fluid to the transmission, wait a minimum of 2 minutes for the oil to fully drain from the fill tube into the transmission before rechecking the fluid level.

(10) Check transmission for leaks.

STANDARD PROCEDURE - FLUID AND FILTER REPLACEMENT

For proper service intervals (Refer to LUBRICATION & MAINTENANCE/MAINTENANCE SCHEDULES - DESCRIPTION). The service fluid fill after a filter change is approximately 3.8 liters (4.0 quarts).

REMOVAL

(1) Hoist and support vehicle on safety stands. (2) Place a large diameter shallow drain pan

beneath the transmission pan.

(3) Remove bolts holding front and sides of pan to

transmission (Fig. 89).

(4) Loosen bolts holding rear of pan to transmis-

sion.

Fig. 89 Transmission Pan

1 - TRANSMISSION 2 - REUSABLE GASKET 3-PAN

Fig. 88 48RE Fluid Fill Graph

Page 75

21 - 204 AUTOMATIC TRANSMISSION - 48RE DR

FLUID AND FILTER (Continued)

(5) Slowly separate front of pan and reusable gasket away from transmission allowing the fluid to drain into drain pan.

(6) Hold up pan and remove remaining bolt holding pan to transmission.

(7) While holding pan level, lower pan and gasket away from transmission.

(8) Pour remaining fluid in pan into drain pan.

(9) Remove screws holding filter to valve body (Fig. 90).

(10) Separate filter from valve body and pour fluid in filter into drain pan.

(11) Dispose of used trans fluid and filter properly.

Fig. 90 Transmission Filter

1 - TRANSMISSION 2 - FILTER

INSTALLATION

(1) Position a new transmission oil filter onto the valve body.

(2) Install the screws to hold the filter to the valve body. Tighten the screws to 4 N·m (35 in.lbs.).

(3) Clean the gasket surfaces of the transmission oil pan and transmission pan rail.

NOTE: The transmission pan oil gasket is reusable. Inspect the sealing surfaces of the gasket. If the sealing ribs on both surfaces appear to be in good condition, clean the gasket of any foreign material and reinstall.

(4) Position the oil pan gasket onto the oil pan.

(5) Position the oil pan and gasket onto the transmission and install several bolts to hold the pan and gasket to the transmission.

(6) Install the remainder of the oil pan bolts.

Tighten the bolts to 13.6 N·m (125 in.lbs.).

(7) Lower vehicle and fill transmission. (Refer to 21 - TRANSMISSION/AUTOMATIC/FLUID - STANDARD PROCEDURE)

STANDARD PROCEDURE - TRANSMISSION FILL

To avoid overfilling transmission after a fluid change or overhaul, perform the following procedure:

(1) Remove dipstick and insert clean funnel in transmission fill tube.

(2) Add following initial quantity of Mopart ATF +4 to transmission:

(a) If only fluid and filter were changed, add 3

pints (1-1/2 quarts) of ATF +4 to transmission.

(b) If transmission was completely overhauled, torque converter was replaced or drained, and cooler was flushed, add 12 pints (6 quarts) of ATF +4 to transmission. (3) Apply parking brakes. (4) Start and run engine at normal curb idle

speed.

(5) Apply service brakes, shift transmission

through all gear ranges then back to NEUTRAL, set parking brake, and leave engine running at curb idle speed.

(6) Remove funnel, insert dipstick and check fluid

level. If level is low, add fluid to bring level to MIN mark on dipstick. Check to see if the oil level is equal on both sides of the dipstick. If one side is noticably higher than the other, the dipstick has picked up some oil from the dipstick tube. Allow the oil to drain down the dipstick tube and re-check.

(7) Drive vehicle until transmission fluid is at nor-

mal operating temperature.

(8) With the engine running at curb idle speed, the

gear selector in NEUTRAL, and the parking brake applied, check the transmission fluid level.

CAUTION: Do not overfill transmission, fluid foaming and shifting problems can result.

(9) Add fluid to bring level up to MAX arrow

mark.

When fluid level is correct, shut engine off, release

park brake, remove funnel, and install dipstick in fill tube.

Page 76

DR AUTOMATIC TRANSMISSION - 48RE 21 - 205

FRONT CLUTCH

DESCRIPTION

The front clutch assembly (Fig. 91) is composed of the front clutch retainer, pressure plate, clutch plates, driving discs, piston, piston return spring, return spring retainer, and snap-rings. The front clutch is the forward-most component in the transmission geartrain and is directly behind the oil pump and is considered a driving component.

OPERATION

To apply the clutch, pressure is applied between the clutch retainer and piston. The fluid pressure is provided by the oil pump, transferred through the control valves and passageways, and enters the clutch through the hub of the reaction shaft support. With pressure applied between the clutch retainer and piston, the piston moves away from the clutch retainer and compresses the clutch pack. This action

applies the clutch pack, allowing torque to flow through the input shaft into the driving discs, and into the clutch plates and pressure plate that are lugged to the clutch retainer. The waved snap-ring is used to cushion the application of the clutch pack.

When pressure is released from the piston, the spring returns the piston to its fully released position and disengages the clutch. The release spring also helps to cushion the application of the clutch assembly. When the clutch is in the process of being released by the release spring, fluid flows through a vent and one-way ball-check-valve located in the clutch retainer. The check-valve is needed to eliminate the possibility of plate drag caused by centrifugal force acting on the residual fluid trapped in the clutch piston retainer.

DISASSEMBLY

(1) Remove the waved snap-ring, reaction plate, clutch plates, and clutch discs.

Fig. 91 48RE Front Clutch Components

1 - INNER PISTON SEAL 7 - CLUTCH DISCS 2 - CLUTCH PISTON 8 - RETAINER SNAP-RING 3 - CLUTCH PISTON SPRING RETAINER 9 - CLUTCH PISTON SPRINGS 4 - CLUTCH PLATES 10 - OUTER PISTON SEAL 5 - CLUTCH PACK SNAP-RING (WAVED) 11 - FRONT CLUTCH RETAINER 6 - REACTION PLATE

Page 77

21 - 206 AUTOMATIC TRANSMISSION - 48RE DR

FRONT CLUTCH (Continued)

(2) Compress clutch piston retainer and piston

springs with Compressor Tool C-3863-A (Fig. 92).

(3) Remove retainer snap-ring and remove com-

pressor tool.

(4) Remove clutch piston springs (Fig. 93). Note position and number of piston springs for assembly reference.

(5) Remove clutch piston from retainer with a twisting motion.

(6) Remove and discard clutch piston inner and outer seals.

INSPECTION

Inspect the front clutch components. Replace the clutch discs if warped, worn, scored, burned or charred, the lugs are damaged, or if the facing is flaking off. Replace the steel plates and reaction plate if heavily scored, warped, or broken. Be sure the driving lugs on the discs and plate are also in good condition. The lugs must not be bent, cracked or damaged in any way.

Replace the piston springs and spring retainer if either are distorted, warped or broken.

Check the lug grooves in the clutch piston retainer. The steel plates should slide freely in the slots. Replace the piston retainer if the grooves are worn or damaged. Also check action of the check ball in the piston retainer. The ball must move freely and not stick.

Fig. 92 Removing Front Clutch Spring Retainer

Snap-Ring

1 - SPECIAL TOOL C-3863-A 2 - SNAP-RING

Replace the retainer bushing if worn, scored, or

there is any doubt about bushing condition.

Fig. 93 48RE Front Clutch Components

Page 78

DR AUTOMATIC TRANSMISSION - 48RE 21 - 207

FRONT CLUTCH (Continued)

Inspect the piston and retainer seal surfaces for nicks or scratches. Minor scratches can be removed with crocus cloth. However, replace the piston and/or retainer if the seal surfaces are seriously scored.

Check the clutch piston check ball. The ball should be securely in place. Replace the piston if the ball is missing, or seized in place.

ASSEMBLY

NOTE: The 48RE transmission uses five plates and discs for the front clutch.

(1) Soak clutch discs in transmission fluid.

(2) Install new inner piston seal onto the outer diameter of the clutch retainer inner hub.

(3)

Install new outer seal onto the clutch piston. Be sure seal lips of both seals face the interior of the retainer.

(4) Lubricate new inner and outer piston seals

with petroleum jelly.

(5) Install clutch piston in retainer. Use twisting motion to seat piston in bottom of retainer. A thin strip of plastic (about 0.015 - 0.020 in. thick), can be used to guide seals into place if necessary.

CAUTION: Never push the clutch piston straight in. This will fold the seals over causing leakage and clutch slip. In addition, never use any type of metal

Fig. 94 Front Clutch Spring Position

1 - 9 SPRING CLUTCH

tool to help ease the piston seals into place. Metal tools will cut, shave, or score the seals.

(6) Install and position nine clutch piston springs

(Fig. 94).

(7) Install spring retainer on top of piston springs. (8) Compress spring retainer and piston springs

with Tool C-3863-A.

(9) Install spring retainer snap-ring and remove

compressor tool.

(10) Install clutch plates and discs (Fig. 95). Five clutch discs, five steel plates and one reaction plate are required.

Fig. 95 48RE Front Clutch Components

Page 79

21 - 208 AUTOMATIC TRANSMISSION - 48RE DR

FRONT CLUTCH (Continued)

(11) Install reaction plate followed by waved snap-

ring.

(12) Check clutch pack clearance with feeler gauge (Fig. 96). Clearance between waved spring and pressure plate should 2.5-4.09 mm (0.098-0.161 in.). If clearance is incorrect, clutch plates, clutch discs, snap-ring, or pressure plate may have to be changed.

Fig. 97 Front Servo

1 - VENT 2 - INNER PISTON 3 - PISTON 4 - SPRING 5 - RELEASE PRESSURE 6 - APPLY PRESSURE 7 - PISTON ROD

Fig. 96 Typical Method Of Measuring Front Clutch

Pack Clearance

1 - FEELER GAUGE 2 - WAVED SNAP-RING 3 - FEELER GAUGE

FRONT SERVO

DESCRIPTION

The kickdown servo (Fig. 97) consists of a two-land piston with an inner piston, a piston rod and guide, and a return spring. The dual-land piston uses seal rings on its outer diameters and an O-ring for the inner piston.

OPERATION

The application of the piston is accomplished by applying pressure between the two lands of the piston. The pressure acts against the larger lower land to push the piston downward, allowing the piston rod to extend though its guide against the apply lever. Release of the servo at the 2-3 upshift is accomplished by a combination of spring and line pressure, acting on the bottom of the larger land of the piston. The small piston is used to cushion the application of the band by bleeding oil through a small orifice in the larger piston. The release timing of the kickdown servo is very important to obtain a smooth but firm shift. The release has to be very quick, just as the front clutch application is taking place. Otherwise, engine runaway or a shift hesitation will occur. To accomplish this, the band retains its holding capacity until the front clutch is applied, giving a small amount of overlap between them.

Page 80

DR AUTOMATIC TRANSMISSION - 48RE 21 - 209

FRONT SERVO (Continued)

DISASSEMBLY

(1) Remove seal ring from rod guide (Fig. 98).

(2) Remove small snap-ring from servo piston rod. Then remove piston rod, spring and washer from piston.

(3) Remove and discard servo component O-ring and seal rings.

Fig. 99 Front Servo

1 - VENT 2 - INNER PISTON 3 - PISTON 4 - SPRING 5 - RELEASE PRESSURE 6 - APPLY PRESSURE 7 - PISTON ROD

Fig. 98 Front Servo

1 - PISTON RINGS 2 - SERVO PISTON 3 - O-RING 4 - SNAP-RING 5 - PISTON ROD GUIDE 6 - SEAL RING 7 - SNAP-RING 8 - SERVO SPRING 9 - WASHER 10 - SPRING 11 - PISTON ROD

CLEANING

Clean the servo piston components (Fig. 99) with solvent and dry them with compressed air.

INSPECTION

Inspect the servo components (Fig. 100). Replace the springs if collapsed, distorted or broken. Replace the guide, rod and piston if cracked, bent, or worn. Discard the servo snap-ring if distorted or warped.

Check the servo piston bore for wear. If the bore is severely scored, or damaged, it will be necessary to replace the case.

Replace any servo component if doubt exists about condition. Do not reuse suspect parts.

ASSEMBLY

Clean and inspect front servo components.

(1) Lubricate new o-ring and seal rings with petroleum jelly and install them on piston, guide and rod.

Fig. 100 Front Servo

1 - PISTON RINGS 2 - SERVO PISTON 3 - O-RING 4 - SNAP-RING 5 - PISTON ROD GUIDE 6 - SEAL RING 7 - SNAP-RING 8 - SERVO SPRING 9 - WASHER 10 - SPRING 11 - PISTON ROD

Page 81

21 - 210 AUTOMATIC TRANSMISSION - 48RE DR

FRONT SERVO (Continued)

(2) Install rod in piston. Install spring and washer on rod. Compress spring and install snap-ring (Fig.

101).

Fig. 101 Front Servo

1 - PISTON RINGS 2 - SERVO PISTON 3 - O-RING 4 - SNAP-RING 5 - PISTON ROD GUIDE 6 - SEAL RING 7 - SNAP-RING 8 - SERVO SPRING 9 - WASHER 10 - SPRING 11 - PISTON ROD

(3) Disengage cable eyelet at transmission shift lever and pull cable adjuster out of mounting bracket (Fig. 102) or (Fig. 103).

Fig. 102 Gearshift Cable at Transmission - RFE

1 - GEARSHIFT CABLE 2 - RFE TRANSMISSION 3 - MANUAL LEVER

GEARSHIFT CABLE

DIAGNOSIS AND TESTING - GEARSHIFT CABLE

(1) Engine starts must be possible with shift lever in PARK or NEUTRAL positions only. Engine starts must not be possible in any other gear position.

(2) With the shift lever in the:

(a) PARK position - Apply upward force on the shift arm and remove pressure. Engine starts must be possible.

(b) PARK position - Apply downward force on the shift arm and remove pressure. Engine starts must be possible.

(d) NEUTRAL position - Engine running and brakes applied, apply upward force on the shift arm. Transmission shall not be able to shift from neutral to reverse.

REMOVAL

(1) Shift transmission into PARK. (2) Raise vehicle.

Fig. 103 Gearshift Cable at Transmission - RE

1 - GEARSHIFT CABLE 2 - RE TRANSMISSION 3 - MANUAL LEVER

Page 82

DR AUTOMATIC TRANSMISSION - 48RE 21 - 211

GEARSHIFT CABLE (Continued)

(4) Lower the vehicle. (5) Remove the dash panel insulation pad as nec-

essary to access the gearshift cable grommet (Fig.

104). (6) Remove grommet from the dash panel. (7) Remove any steering column trim necessary to

access the gearshift cable and BTSI mechanism.

(8) Disconnect the BTSI wiring connector. (9) Disconnect cable at lower column bracket and

shift lever pin and pull the cable through the dash panel opening into the vehicle (Fig. 105).

INSTALLATION

(1) Route the transmission end of the gearshift

cable through the opening in the dash panel (Fig.

106). (2) Seat the cable grommet into the dash panel

opening.

(3) Snap the cable into the steering column

bracket so the retaining ears (Fig. 107) are engaged and snap the cable eyelet onto the shift lever ball stud.

Fig. 104 Gearshift Cable at the Dash Panel

1 - GEARSHIFT CABLE 2 - GROMMET

Fig. 105 Gearshift Cable at Steering Column

1 - STEERING COLUMN 2 - GEARSHIFT CABLE 3 - GEARSHIFT CABLE LOCK TAB 4 - BTSI SOLENOID LOCK TAB 5 - BTSI CONNECTOR

(10) Remove gearshift cable from vehicle.

Fig. 106 Gearshift Cable at the Dash Panel

1 - GEARSHIFT CABLE 2 - GROMMET

Fig. 107 Gearshift Cable at Steering Column

1 - STEERING COLUMN 2 - GEARSHIFT CABLE 3 - GEARSHIFT CABLE LOCK TAB 4 - BTSI SOLENOID LOCK TAB 5 - BTSI CONNECTOR

(4) Raise the vehicle. (5) Place the transmission manual shift lever in

the “PARK” detent (rearmost) position and rotate prop shaft to ensure transmission is in PARK.

Page 83

21 - 212 AUTOMATIC TRANSMISSION - 48RE DR

GEARSHIFT CABLE (Continued)

(6) Route the gearshift cable through the transmission mounting bracket and secure the cable by snapping the cable retaining ears into the transmission bracket and snapping the cable eyelet on the manual shift lever ball stud.

(7) Lower vehicle.

(8) Lock the shift cable adjustment by pressing the cable adjuster lock tab downward until it snaps into place.

(9) Check for proper operation of the transmission range sensor.

(10) Adjust the gearshift cable (Refer to 21 TRANSMISSION/AUTOMATIC/GEAR SHIFT CABLE - ADJUSTMENTS) and BTSI mechanism (Refer to 21 - TRANSMISSION/AUTOMATIC/ BRAKE TRANSMISSION SHIFT INTERLOCK SYSTEM - ADJUSTMENTS) as necessary.

ADJUSTMENTS

GEARSHIFT CABLE

Check adjustment by starting the engine in PARK and NEUTRAL. Adjustment is CORRECT if the engine starts only in these positions. Adjustment is INCORRECT if the engine starts in one but not both positions. If the engine starts in any position other than PARK or NEUTRAL, or if the engine will not start at all, the transmission range sensor may be faulty.

Gearshift Adjustment Procedure

(1) Shift transmission into PARK.

(2) Release cable adjuster lock tab (underneath the steering column) (Fig. 108) to unlock cable.

(3) Raise vehicle.

(4) Disengage the cable eyelet from the transmission manual shift lever.

(5) Verify transmission shift lever is in PARK detent by moving lever fully rearward. Last rearward detent is PARK position.

(6) Verify positive engagement of transmission park lock by attempting to rotate propeller shaft. Shaft will not rotate when park lock is engaged.

(7) Snap the cable eyelet onto the transmission manual shift lever.

(8) Lower vehicle.

(9) Lock shift cable by pressing cable adjuster lock tab downward until it snaps into place.

(10) Check engine starting. Engine should start only in PARK and NEUTRAL

Fig. 108 Gearshift Cable at Steering Column

1 - STEERING COLUMN 2 - GEARSHIFT CABLE 3 - GEARSHIFT CABLE LOCK TAB 4 - BTSI SOLENOID LOCK TAB 5 - BTSI CONNECTOR

Page 84

DR AUTOMATIC TRANSMISSION - 48RE 21 - 213

OIL PUMP

DESCRIPTION

The oil pump (Fig. 109) is located in the pump housing inside the bell housing of the transmission case. The oil pump consists of an inner and outer gear, a housing, and a reaction shaft support.

OPERATION

As the torque converter rotates, the converter hub rotates the inner and outer gears. As the gears rotate, the clearance between the gear teeth increases in the crescent area, and creates a suction at the inlet side of the pump. This suction draws fluid through the pump inlet from the oil pan. As the clearance between the gear teeth in the crescent area decreases, it forces pressurized fluid into the pump outlet and to the valve body.

1 - OIL SEAL 7 - BOLTS (6) 2 - VENT BAFFLE 8 - #1 THRUST WASHER (SELECTIVE) 3 - OIL PUMP BODY 9 - INNER GEAR 4 - GASKET 10 - OUTER GEAR 5 - REACTION SHAFT SUPPORT 11 - “O” RING 6 - SEAL RINGS 12 - TORQUE CONVERTER SEAL RING

Fig. 109 Oil Pump Assembly

Page 85

21 - 214 AUTOMATIC TRANSMISSION - 48RE DR

OIL PUMP (Continued)

DISASSEMBLY

(1) Mark position of support in oil pump body for assembly alignment reference. Use scriber or paint to make alignment marks.

(2) Place pump body on two wood blocks.

(3) Remove reaction shaft support bolts and separate support from pump body (Fig. 110).

(4) Remove pump inner and outer gears (Fig. 111).

(5) Remove o-ring seal from pump body (Fig. 112). Discard seal after removal.

(6) Remove oil pump seal with Remover Tool C-3981. Discard seal after removal.

Fig. 110 Reaction Shaft Support

1 - OIL PUMP 2 - REACTION SHAFT SUPPORT

CLEANING

Clean pump and support components with solvent and dry them with compressed air.

INSPECTION

Check condition of the seal rings and thrust washer on the reaction shaft support. The seal rings do not need to be replaced unless cracked, broken, or severely worn.

Inspect the pump and support components. Replace the pump or support if the seal ring grooves or machined surfaces are worn, scored, pitted, or damaged. Replace the pump gears if pitted, worn chipped, or damaged.

Inspect the pump bushing. Then check the reaction shaft support bushing. Replace either bushing only if heavily worn, scored or damaged. It is not necessary to replace the bushings unless they are actually damaged.

Clearance between outer gear and reaction shaft housing should be 0.010 to 0.063 mm (0.0004 to

0.0025 in.). Clearance between inner gear and reaction shaft housing should be 0.010 to 0.063 mm (0.0004 to 0.0025 in.). Both clearances can be mea-

Fig. 111 Pump Gears

1 - GEAR BORE 2 - PUMP BODY 3 - INNER GEAR 4 - OUTER GEAR

sured at the same time by installing the gears in the pump body and measure pump component clearances as follows:

(1) Position an appropriate piece of Plastigage™

across both gears.

(2) Align the plastigage to a flat area on the reac-

tion shaft housing.

(3) Install the reaction shaft to the pump housing.

(4) Separate the reaction shaft housing from the pump housing and measure the Plastigage™ following the instructions supplied with it.

Clearance between inner gear tooth and outer gear should be 0.051 to 0.19 mm (0.002 to 0.0075 in.). Measure clearance with an appropriate feeler gauge (Fig. 113).

Clearance between outer gear and pump housing should be 0.10 to 0.229 mm (0.004 to 0.009 in.). Measure clearance with an appropriate feeler gauge.

ASSEMBLY

(1) Lubricate pump gears with transmission fluid and install them in pump body.

(2) Install thrust washer on reaction shaft support hub. Lubricate washer with petroleum jelly or transmission fluid before installation.

(3) If reaction shaft seal rings are being replaced, install new seal rings on support hub. Lubricate seal rings with transmission fluid or petroleum jelly after installation. Squeeze each ring until ring ends are securely hooked together.

Page 86

DR AUTOMATIC TRANSMISSION - 48RE 21 - 215

OIL PUMP (Continued)

Fig. 112 Oil Pump Assembly

CAUTION: The reaction shaft support seal rings will break if overspread, or twisted. If new rings are being installed, spread them only enough for installation. Also be very sure the ring ends are securely hooked together after installation. Otherwise, the rings will either prevent pump installation, or break during installation.

Fig. 113 Checking Pump Gear Tip Clearance

1 - FEELER GAUGE 2 - INNER GEAR 3 - OUTER GEAR

Page 87

21 - 216 AUTOMATIC TRANSMISSION - 48RE DR

OIL PUMP (Continued)

(4) Align and install reaction shaft support on

pump body.

(5) Install bolts attaching reaction shaft support to

pump. Tighten bolts to 20 N·m (175 in. lbs.) torque.

(6) Install new pump seal with Installer Tool C-3860-A (Fig. 114). Use hammer or mallet to tap seal into place.

(7) Install new o-ring on pump body. Lubricate oil seal and o-ring with petroleum jelly.

(8) Cover pump assembly to prevent dust entry and set aside for assembly installation.

Fig. 115 Output Shaft Front Bearing

1 - OUTPUT SHAFT FRONT BEARING 2 - SNAP-RING 3 - OUTPUT SHAFT 4 - GROOVE TO REAR 5 - OVERDRIVE GEARTRAIN

Fig. 114 Oil Pump Seal

1 - SPECIAL TOOL C-3860-A 2 - PUMP BODY 3 - PUMP SEAL

OUTPUT SHAFT FRONT BEARING

REMOVAL

(1) Remove overdrive unit from the vehicle.

(2) Remove overdrive geartrain from housing.

(3) Remove snap-ring holding output shaft front bearing to overdrive geartrain. (Fig. 115).

(4) Pull bearing from output shaft.

INSTALLATION

(1) Place replacement bearing in position on geartrain with locating retainer groove toward the rear.

(2) Push bearing onto shaft until the snap-ring groove is visible.

(3) Install snap-ring to hold bearing onto output shaft.

(4) Install overdrive geartrain into housing.

(5) Install overdrive unit in vehicle.

OUTPUT SHAFT REAR BEARING

REMOVAL

(1) Remove overdrive unit from the vehicle. (Refer

to 21 - TRANSMISSION/AUTOMATIC/OVERDRIVE

- REMOVAL) (2) Remove overdrive geartrain from housing. (3) Remove snap-ring holding output shaft rear

bearing into overdrive housing (Fig. 116).

(4) Using a suitable driver inserted through the

rear end of housing, drive bearing from housing.

Fig. 116 Output Shaft Rear Bearing

1 - OUTPUT SHAFT REAR BEARING 2 - OVERDRIVE HOUSING 3 - SNAP-RING

Page 88

DR AUTOMATIC TRANSMISSION - 48RE 21 - 217

OUTPUT SHAFT REAR BEARING (Continued)

INSTALLATION

(1) Place replacement bearing in position in hous-

ing.

(2) Using a suitable driver, drive bearing into

housing until the snap-ring groove is visible.

(3) Install snap-ring to hold bearing into housing

(Fig. 116).

(4) Install overdrive geartrain into housing. (5) Install overdrive unit in vehicle.

OVERDRIVE CLUTCH

DESCRIPTION

The overdrive clutch (Fig. 117) is composed of the pressure plate, clutch plates, holding discs, overdrive piston retainer, piston, piston spacer, and snap-rings. The overdrive clutch is the forwardmost component in the transmission overdrive unit and is considered a holding component. The overdrive piston retainer, piston, and piston spacer are located on the rear of the main transmission case.

NOTE: The number of discs and plates may vary with each engine and vehicle combination.

OPERATION

To apply the clutch, pressure is applied between the piston retainer and piston. The fluid pressure is provided by the oil pump, transferred through the control valves and passageways, and enters the clutch through passages at the lower rear portion of the valve body area. With pressure applied between the piston retainer and piston, the piston moves away from the piston retainer and compresses the clutch pack. This action applies the clutch pack, allowing torque to flow through the intermediate shaft into the overdrive planetary gear set. The overdrive clutch discs are attached to the overdrive clutch hub while the overdrive clutch plates, reaction plate, and pressure plate are lugged to the overdrive housing. This allows the intermediate shaft to transfer the engine torque to the planetary gear and overrunning clutch. This drives the planetary gear inside the annulus, which is attached to the overdrive clutch drum and output shaft, creating the desired gear ratio. The waved snap-ring is used to cushion the application of the clutch pack for the 5 disc version of the overdrive clutch. The 6 disc overdrive clutch does not use a waved snap-ring.

1 - REACTION PLATE 2 - PRESSURE PLATE

Fig. 117 Overdrive Clutch

Page 89

21 - 218 AUTOMATIC TRANSMISSION - 48RE DR

OVERDRIVE UNIT

REMOVAL

(1) Shift transmission into PARK. (2) Raise vehicle. (3) Remove transfer case, if equipped.

(4) Mark propeller shaft universal joint(s) and axle pinion yoke, or the companion flange and flange yoke, for alignment reference at installation, if necessary.

(5) Disconnect and remove the rear propeller shaft, if necessary. (Refer to 3 - DIFFERENTIAL & DRIVELINE/PROPELLER SHAFT/PROPELLER SHAFT REMOVAL)

(6) Remove transmission oil pan, remove gasket, drain oil and reinstall pan.

(7) If overdrive unit had malfunctioned, or if fluid is contaminated, remove entire transmission. If diagnosis indicated overdrive problems only, remove just the overdrive unit.

(8) Support transmission with transmission jack.

(9) Remove bolts attaching overdrive unit to transmission (Fig. 118).

CAUTION: Support the overdrive unit with a jack before moving it rearward. This is necessary to prevent damaging the intermediate shaft. Do not allow the shaft to support the entire weight of the overdrive unit.

(11) If overdrive unit does not require service, immediately insert Alignment Tool 6227-2 in splines of planetary gear and overrunning clutch to prevent splines from rotating out of alignment. If misalignment occurs, overdrive unit will have to be disassembled in order to realign splines.

(12) Remove and retain overdrive piston thrust bearing. Bearing may remain on piston or in clutch hub during removal.

(13) Position drain pan on workbench.

(14) Place overdrive unit over drain pan. Tilt unit to drain residual fluid from case.

(15) Examine fluid for clutch material or metal fragments. If fluid contains these items, overhaul will be necessary.

(16) If overdrive unit does not require any service, leave alignment tool in position. Tool will prevent accidental misalignment of planetary gear and overrunning clutch splines.

DISASSEMBLY

(1) Remove transmission speed sensor and o-ring seal from overdrive case (Fig. 119).

(2) Remove overdrive piston thrust bearing (Fig.

120).

Fig. 118 Overdrive Unit Bolts

1 - OVERDRIVE UNIT 2 - ATTACHING BOLTS (7)

(10) Carefully work overdrive unit off intermediate shaft. Do not tilt unit during removal. Keep it as level as possible.

Fig. 119 Transmission Speed Sensor

1 - SOCKET AND WRENCH 2 - SPEED SENSOR 3 - O-RING

Page 90

DR AUTOMATIC TRANSMISSION - 48RE 21 - 219

OVERDRIVE UNIT (Continued)

(2) Remove intermediate shaft spacer (Fig. 122). Retain spacer. It is a select fit part and may possibly be reused.

Fig. 120 Overdrive Piston Thrust Bearing Removal/

Installation

1 - THRUST BEARING 2 - OVERDRIVE PISTON 3 - THRUST PLATE

OVERDRIVE PISTON

(1) Remove overdrive piston thrust plate (Fig.

121). Retain thrust plate. It is a select fit part and may possibly be reused.

Fig. 122 Intermediate Shaft Spacer Location

1 - INTERMEDIATE SHAFT 2 - INTERMEDIATE SHAFT SPACER (SELECT FIT)

(3) Remove overdrive piston from retainer (Fig.

123).

Fig. 121 Overdrive Piston Thrust Plate Removal/

Installation

1 - OVERDRIVE PISTON 2 - OVERDRIVE PISTON SPACER (SELECT FIT)

Fig. 123 Overdrive Piston Removal

1 - PISTON RETAINER 2 - OVERDRIVE PISTON

Page 91

21 - 220 AUTOMATIC TRANSMISSION - 48RE DR

OVERDRIVE UNIT (Continued)

OVERDRIVE CLUTCH PACK

(1) Remove overdrive clutch pack wire retaining

ring (Fig. 124).

(2) Remove overdrive clutch pack (Fig. 125). (3) Note position of clutch pack components for

assembly reference (Fig. 126).

Fig. 126 Overdrive Clutch Component Position -

Typical

1 - REACTION PLATE 2 - CLUTCH PLATES 3 - PRESSURE PLATE 4 - CLUTCH DISCS

Fig. 124 Removing Overdrive Clutch Pack Retaining

Ring

1 - OVERDRIVE CLUTCH PACK RETAINING RING

Fig. 125 Overdrive Clutch Pack Removal

1 - OVERDRIVE CLUTCH PACK

OVERDRIVE GEARTRAIN

(1) Remove overdrive clutch wave spring (Fig.

127), 5 disc clutch only. (2) Remove overdrive clutch reaction snap-ring

(Fig. 128). Note that snap-ring is located in same groove as wave spring.

Fig. 127 Overdrive Clutch Wave Spring Removal - 5

Disc Clutch Only

1 - WAVE SPRING

Fig. 128 Overdrive Clutch Reaction Snap-Ring

Removal

1 - REACTION RING 2 - CLUTCH HUB

Page 92

DR AUTOMATIC TRANSMISSION - 48RE 21 - 221

OVERDRIVE UNIT (Continued)

(3) Remove Torx™ head screws that attach access

cover and gasket to overdrive case (Fig. 129).

(4) Remove access cover and gasket (Fig. 130).

Fig. 129 Access Cover Screw Removal

1 - TORX SCREWDRIVER (T25) 2 - ACCESS COVER SCREWS

(6) Lift gear case up and off geartrain assembly

(Fig. 132).

Fig. 132 Removing Geartrain

1 - GEARTRAIN ASSEMBLY 2 - GEAR CASE

(7) Remove snap-ring that retains rear bearing on

output shaft.

(8) Remove rear bearing from output shaft (Fig.

133).

Fig. 130 Access Cover And Gasket Removal

1 - ACCESS COVER AND GASKET

(5) Expand output shaft bearing snap-ring with

expanding-type snap-ring pliers. Then push output shaft forward to release shaft bearing from locating ring (Fig. 131).

Fig. 131 Releasing Bearing From Locating Ring

1 - EXPAND BEARING LOCATING RING WITH SNAP-RING PLIERS 2 - ACCESS HOLE

Fig. 133 Rear Bearing Removal

1 - OUTPUT SHAFT 2 - REAR BEARING 3 - SNAP-RING

Page 93

21 - 222 AUTOMATIC TRANSMISSION - 48RE DR

OVERDRIVE UNIT (Continued)

DIRECT CLUTCH, HUB AND SPRING

WARNING: THE NEXT STEP IN DISASSEMBLY INVOLVES COMPRESSING THE DIRECT CLUTCH SPRING. IT IS EXTREMELY IMPORTANT THAT PROPER EQUIPMENT BE USED TO COMPRESS THE SPRING AS SPRING FORCE IS APPROXIMATELY 830 POUNDS. USE SPRING COMPRESSOR TOOL 6227-1 AND A HYDRAULIC SHOP PRESS WITH A MINIMUM RAM TRAVEL OF 5-6 INCHES. THE PRESS MUST ALSO HAVE A BED THAT CAN BE ADJUSTED UP OR DOWN AS REQUIRED. RELEASE CLUTCH SPRING TENSION SLOWLY AND COMPLETELY TO AVOID PERSONAL INJURY.

(1) Mount geartrain assembly in shop press (Fig. 134). (2) Position Compressor Tool 6227-1 on clutch hub

(Fig. 134). Support output shaft flange with steel press plates as shown and center assembly under press ram.

(3) Apply press pressure slowly. Compress hub and

spring far enough to expose clutch hub retaining ring and relieve spring pressure on clutch pack snap-ring (Fig. 134).

(4) Remove direct clutch pack snap-ring (Fig. 135). (5)

Remove direct clutch hub retaining ring (Fig.

136).

Fig. 135 Direct Clutch Pack Snap-Ring Removal

1 - CLUTCH HUB 2 - SPECIAL TOOL 6227-1 3 - DIRECT CLUTCH PACK SNAP-RING 4 - PRESS PLATES 5 - CLUTCH DRUM

Fig. 134 Geartrain Mounted In Shop Press

1 - PRESS RAM 2 - SPECIAL TOOL C-3995-A (OR SIMILAR TOOL) 3 - CLUTCH HUB 4 - PLATES 5 - PRESS BED 6 - SPECIAL TOOL 6227-1

Fig. 136 Direct Clutch Hub Retaining Ring Removal

1 - SPECIAL TOOL 6227-1 2 - CLUTCH HUB RETAINING RING 3 - PRESS BED 4 - PRESS PLATES

Page 94

DR AUTOMATIC TRANSMISSION - 48RE 21 - 223

OVERDRIVE UNIT (Continued)

(6) Release press load slowly and completely (Fig.

137). (7) Remove Special Tool 6227-1. Then remove

clutch pack from hub (Fig. 137). Note the orientation of the clutch discs. The clutch pack consists of 23 single-sided discs and they must be installed in the same orientation as they were removed.

Fig. 138 Direct Clutch Hub And Spring Removal

1 - DIRECT CLUTCH SPRING 2 - DIRECT CLUTCH HUB

Fig. 137 Direct Clutch Pack Removal

1 - SPECIAL TOOL 6227-1 2 - DIRECT CLUTCH HUB 3 - DIRECT CLUTCH PACK

GEARTRAIN

(1) Remove direct clutch hub and spring (Fig. 138). (2) Remove sun gear and spring plate. Then

remove planetary thrust bearing and planetary gear (Fig. 139).

Fig. 139 Removing Sun Gear, Thrust Bearing And

Planetary Gear

1 - PLANETARY GEAR 2 - PLANETARY THRUST BEARING 3 - CLUTCH SPRING PLATE 4 - SPRING PLATE SNAP-RING 5 - SUN GEAR

Page 95

21 - 224 AUTOMATIC TRANSMISSION - 48RE DR

OVERDRIVE UNIT (Continued)

(3) Remove overrunning clutch assembly with

expanding type snap-ring pliers (Fig. 140). Insert pliers into clutch hub. Expand pliers to grip hub splines and remove clutch with counterclockwise, twisting motion.

(4) Remove thrust bearing from overrunning

clutch hub.

(5) Remove overrunning clutch from hub. (6) Mark position of annulus gear and direct clutch

drum for assembly alignment reference (Fig. 141). Use small center punch or scriber to make alignment marks.

(7) Remove direct clutch drum rear retaining ring

(Fig. 142).

(8) Remove direct clutch drum outer retaining ring

(Fig. 143).

Fig. 142 Clutch Drum Inner Retaining Ring Removal

1 - INNER RETAINING RING 2 - DIRECT CLUTCH DRUM 3 - ANNULUS GEAR

Fig. 140 Overrunning Clutch Assembly Removal/

Installation

1 - OVERRUNNING CLUTCH 2 - NEEDLE BEARING

Fig. 141 Marking Direct Clutch Drum And Annulus

Gear For Assembly Alignment

1 - DIRECT CLUTCH DRUM 2 - HAMMER 3 - PUNCH

Fig. 143 Clutch Drum Outer Retaining Ring Removal

1 - OUTER RETAINING RING

Page 96

DR AUTOMATIC TRANSMISSION - 48RE 21 - 225

OVERDRIVE UNIT (Continued)

(9) Mark annulus gear and output shaft for assem-

bly alignment reference (Fig. 144). Use punch or scriber to mark gear and shaft.

Fig. 146 Annulus Gear Removal

1 - OUTPUT SHAFT 2 - ANNULUS GEAR

Fig. 144 Marking Annulus Gear And Output Shaft

For Assembly Alignment

1 - OUTPUT SHAFT 2 - HAMMER 3 - PUNCH

(10) Remove snap-ring that secures annulus gear

on output shaft (Fig. 145). Use two screwdrivers to unseat and work snap-ring out of groove as shown.

(11) Remove annulus gear from output shaft (Fig.

146). Use rawhide or plastic mallet to tap gear off

shaft.

GEAR CASE AND PARK LOCK

(1) Remove locating ring from gear case. (2) Remove park pawl shaft retaining bolt and

remove shaft, pawl and spring.

(3) Remove reaction plug snap-ring and remove

reaction plug.

(4) Remove output shaft seal.

CLEANING

Clean the geartrain and case components with solvent. Dry all parts except the bearings with compressed air. Allow bearings to air dry.

Do not use shop towels for wiping parts dry unless the towels are made from a lint-free material. A sufficient quantity of lint (from shop towels, cloths, rags, etc.) could plug the transmission filter and fluid passages.

Discard the old case gasket and seals. Do not attempt to salvage these parts. They are not reusable. Replace any of the overdrive unit snap-rings if distorted or damaged.

Minor nicks or scratches on components can be smoothed with crocus cloth. However, do not attempt to reduce severe scoring on any components with abrasive materials. Replace severely scored components; do not try to salvage them.

Fig. 145 Annulus Gear Snap-Ring Removal

1 - OUTPUT SHAFT 2 - ANNULUS GEAR 3 - SNAP-RING

INSPECTION

Check condition of the park lock components and the overdrive case.

Check the bushings in the overdrive case. Replace the bushings if severely scored or worn. Also replace the case seal if loose, distorted, or damaged.

Examine the overdrive and direct clutch discs and plates. Replace the discs if the facing is worn, severely scored, or burned and flaking off. Replace the clutch plates if worn, heavily scored, or cracked.

Page 97

21 - 226 AUTOMATIC TRANSMISSION - 48RE DR

OVERDRIVE UNIT (Continued)

Check the lugs on the clutch plates for wear. The plates should slide freely in the drum. Replace the plates or drum if binding occurs.

Check condition of the annulus gear, direct clutch hub, clutch drum and clutch spring. Replace the gear, hub and drum if worn or damaged. Replace the spring if collapsed, distorted, or cracked.

Be sure the splines and lugs on the gear, drum and hub are in good condition. The clutch plates and discs should slide freely in these components.

Inspect the thrust bearings and spring plate. Replace the plate if worn or scored. Replace the bearings if rough, noisy, brinnelled, or worn.

Inspect the planetary gear assembly and the sun gear and bushings. If either the sun gear or the bushings are damaged, replace the gear and bushings as an assembly. The gear and bushings are not serviced separately.

The planetary carrier and pinions must be in good condition. Also be sure the pinion pins are secure and in good condition. Replace the carrier if worn or damaged.

Inspect the overrunning clutch and race. The race surface should be smooth and free of scores. Replace the overrunning clutch assembly or the race if either assembly is worn or damaged in any way.

Replace the shaft pilot bushing and inner bushing if damaged. Replace either shaft bearing if rough or noisy. Replace the bearing snap-rings if distorted or cracked.

Check the machined surfaces on the output shaft. These surfaces should clean and smooth. Very minor nicks or scratches can be smoothed with crocus cloth. Replace the shaft if worn, scored or damaged in any way.

Inspect the output shaft bushings. The small bushing is the intermediate shaft pilot bushing. The large bushing is the overrunning clutch hub bushing. Replace either bushing if scored, pitted, cracked, or worn.

(2) Install annulus gear on output shaft, if removed. Then install annulus gear retaining snapring (Fig. 147).

(3) Align and install clutch drum on annulus gear (Fig. 148). Be sure drum is engaged in annulus gear lugs.

(4) Install clutch drum outer retaining ring (Fig.

148).

Fig. 147 Annulus Gear Installation

1 - SNAP-RING 2 - OUTPUT SHAFT FRONT BEARING 3 - ANNULUS GEAR

ASSEMBLY

GEARTRAIN AND DIRECT CLUTCH

(1) Soak direct clutch and overdrive clutch discs in Mopart ATF +4, Automatic Transmission fluid. Allow discs to soak for 10-20 minutes.

Fig. 148 Clutch Drum And Outer Retaining Ring

Installation

1 - ANNULUS GEAR 2 - OUTER SNAP-RING 3 - CLUTCH DRUM

Page 98

DR AUTOMATIC TRANSMISSION - 48RE 21 - 227

OVERDRIVE UNIT (Continued)

(5) Slide clutch drum forward and install inner retaining ring (Fig. 149).

(6) Install rear bearing and snap-ring on output shaft (Fig. 150). Be sure locating ring groove in bearing is toward rear.

Fig. 151 Assembling Overrunning Clutch And Hub

1 - CLUTCH HUB 2 - OVERRUNNING CLUTCH

Fig. 149 Clutch Drum Inner Retaining Ring

Installation

1 - ANNULUS GEAR 2 - INNER SNAP-RING 3 - CLUTCH DRUM

Fig. 150 Rear Bearing And Snap-Ring Installation

1 - REAR BEARING 2 - SNAP-RING

(7) Install overrunning clutch on hub (Fig. 151). Note that clutch only fits one way. Shoulder on clutch should seat in small recess at edge of hub.

(8) Install thrust bearing on overrunning clutch hub. Use generous amount of petroleum jelly to hold bearing in place for installation. Bearing fits one way only. Be sure bearing is seated squarely against hub. Reinstall bearing if it does not seat squarely.

(9) Install overrunning clutch in output shaft (Fig.

152). Insert snap-ring pliers in hub splines. Expand pliers to grip hub. Then install assembly with counterclockwise, twisting motion.

Fig. 152 Overrunning Clutch Installation

1 - CLUTCH DRUM 2 - OVERRUNNING CLUTCH ASSEMBLY 3 - EXPANDING-TYPE SNAP-RING PLIERS 4 - CLUTCH DRUM 5 - ANNULUS GEAR 6 - OVERRUNNING CLUTCH ASSEMBLY SEATED IN OUTPUT SHAFT

Page 99

21 - 228 AUTOMATIC TRANSMISSION - 48RE DR

OVERDRIVE UNIT (Continued)

(10) Install planetary gear in annulus gear (Fig.

153). Be sure planetary pinions are fully seated in annulus gear before proceeding.

Fig. 155 Sun Gear Installation

1 - SUN GEAR AND SPRING PLATE ASSEMBLY

(14) Mount assembled output shaft, annulus gear,

Fig. 153 Planetary Gear Installation

1 - PLANETARY GEAR 2 - ANNULUS GEAR

(11) Coat planetary thrust bearing and bearing contact surface of spring plate with generous amount of petroleum jelly. This will help hold bearing in place during installation.

(12) Install planetary thrust bearing on sun gear (Fig. 154). Slide bearing onto gear and seat it against spring plate as shown. Bearing fits one way only. If it does not seat squarely against spring plate, remove and reposition bearing.

(13) Install assembled sun gear, spring plate and thrust bearing (Fig. 155). Be sure sun gear and thrust bearing are fully seated before proceeding.

and clutch drum in shop press. Direct clutch spring, hub and clutch pack are easier to install with assembly mounted in press.

(15) Align splines in hubs of planetary gear and

overrunning clutch with Alignment tool 6227-2 (Fig.

156). Insert tool through sun gear and into splines of both hubs. Be sure alignment tool is fully seated before proceeding.

Fig. 154 Planetary Thrust Bearing Installation

1 - SPRING PLATE 2 - PLANETARY THRUST BEARING 3 - SUN GEAR

Fig. 156 Alignment Tool Installation

1 - SPECIAL TOOL 6227-2 2 - PRESS PLATES 3 - ASSEMBLED DRUM AND ANNULUS GEAR 4 - SUN GEAR

Page 100

DR AUTOMATIC TRANSMISSION - 48RE 21 - 229

OVERDRIVE UNIT (Continued)

(16) Install direct clutch spring (Fig. 157). Be sure spring is properly seated on spring plate.

Fig. 157 Direct Clutch Spring Installation

1 - SPECIAL TOOL 6227-2 2 - DIRECT CLUTCH SPRING 3 - CLUTCH HUB 4 - PRESS PLATES

NOTE: The direct clutch in a 48RE transmission uses 23 single-sided clutch discs.

(17) Assemble and install direct clutch pack on hub as follows:

(a) Install direct clutch reaction plate on clutch hub first. Note that one side of reaction plate is counterbored. Be sure this side faces rearward. Splines at rear of hub are raised slightly. Counterbore in plate fits over raised splines. Plate should be flush with this end of hub (Fig. 158).

Fig. 158 Correct Position Of Direct Clutch Reaction

Plate

1-REACTION PLATE COUNTERBORE

2 - DIRECT CLUTCH REACTION PLATE (FLUSH WITH END OF HUB) 3 - CLUTCH HUB

(b) Install first clutch disc with internal splines friction side up, followed by a disc with external lugs friction side up. Continue alternating internal and external discs until all discs have been installed.

Chrysler 48RE User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual