Allison Transmission HT 700, HTB 700, CLT 700, CLBT 700 Service Manual

Mechanic’s
Tips
Allison Transmission
Division of General Motors Corporation
P.O. B ox 894 Indianapolis, Indiana 46206-0894
Printed in U.S.A. Copyright © 1995 General Motors Corp.
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Proper service and repair is important to the safe, reliable operation of the equipment. The service procedures recommended by Allison Transmission and described in this handbook are effective methods for performing service operations. Some of these service operations require the use of tools specially designed for the purpose. The special tools should be used when and as recommended.
Three types of headings are used in this manual to attract your attention. These warnings and cautions advise of specic methods or actions that can result in personal injury, damage to the equipment, or cause the equipment to become unsafe.
WARNING: A warning is used when an operating procedure, practice, etc., if not correctly followed, could result in personal injury or loss of life.
CAUTION: A caution is used when an operating procedure, practice, etc., if not strictly observed, could result in damage to or destruction of equipment.
NOTE: A note is used when an operating procedure, practice, etc., is essential to highlight.
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Paragraph Description Page
1–1. Periodic Inspection and Care . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1–2. Importance of Proper Transmission Fluid Level . . . . . . . . . . . . 1
1–3. Transmission Fluid Check Procedures. . . . . . . . . . . . . . . . . . . . 2
1–4. Keeping Transmission Fluid Clean . . . . . . . . . . . . . . . . . . . . . . 5
1–5. Automatic Transmission Fluid Recommendations . . . . . . . . . . 5
1–6. Transmission Fluid and Filter Change Intervals . . . . . . . . . . . . 6
1–7. Fluid Temperatures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1–8. High-Efficiency, Main-Pressure External Filter Change. . . . . . 8
1–9. Transmission Fluid Contamination . . . . . . . . . . . . . . . . . . . . . . 8
1–10. Transmission Fluid and Filter Change Procedure . . . . . . . . . . . 9
1–11. Auxiliary Filter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1–12. Breather . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1–13. Transmission Stall Test and Neutral Cool-Down Check . . . . . . 10
2–1. Draining Transmission. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2–2. Disconnecting Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2–3. Uncoupling From Driveline, Engine, and Vehicle. . . . . . . . . . . 14
2–4. Removing the Transmission. . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2–5. Removing Input and Output Flanges or Yokes . . . . . . . . . . . . . 14
2–6. Rebuild, Overhaul Instructions . . . . . . . . . . . . . . . . . . . . . . . . . 15
3–1. Checking Input Components . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3–2. Installing Output Flange and Input Flange
(Remote-Mounted Transmission) . . . . . . . . . . . . . . . . . . . . . . . 16
3–3. Installing PTO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3–4. Installing Transmission Fill Tube and Seal . . . . . . . . . . . . . . . . 18
3–5. Checking Plugs, Openings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
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Paragraph Description Page
4–1. Engine, Transmission Adaptation Requirements. . . . . . . . . . . . 19
4–2. Checking Flexplate Drive Assembly . . . . . . . . . . . . . . . . . . . . . 20
4–3. Checking Input Drive Components
(Remote-Mounted Transmissions). . . . . . . . . . . . . . . . . . . . . . . 20
4–4. Chassis and Driveline Inspection . . . . . . . . . . . . . . . . . . . . . . . . 22
4–5. Cooler, Filter, and Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4–6. Checking Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5–1. Handling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
5–2. Mounting to Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
5–3. Installing Transmission Mounting Components . . . . . . . . . . . . 28
5–4. Coupling to Driveline. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
5–5. Coupling to Engine (Remote-Mounted Transmission) . . . . . . . 28
5–6. Connecting Input Retarder Control . . . . . . . . . . . . . . . . . . . . . . 29
5–7. Connecting Output Retarder Control . . . . . . . . . . . . . . . . . . . . . 29
5–8. Connecting Power Takeoff Controls . . . . . . . . . . . . . . . . . . . . . 29
5–9. Connecting Parking Brake Control . . . . . . . . . . . . . . . . . . . . . . 30
5–10. Connecting Cooler, Filter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
5–11. Installing Auxiliary Filter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
5–12. Connecting Speedometer Drive . . . . . . . . . . . . . . . . . . . . . . . . . 30
5–13. Installing Temperature and Pressure Sensors,
Connecting Electrical Components . . . . . . . . . . . . . . . . . . . . . . 32
5–14. Filling the Hydraulic System . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
6–1. Installation Checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
6–2. Road Test and Vehicle Operation Checklist . . . . . . . . . . . . . . . 35
7–1. Owner Assistance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
7–2. Service Literature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
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This handbook is a mechanic’s reference for removing, installing, and maintaining the HT, HTB, CL(B)T 700 Commercial Electronic Control Series Automatic Transmissions. All features of the transmission and vehicle involved in installation procedures are discussed. The information presented will help the mechanic to remove, install, and maintain the transmission in a manner that assures satisfactory operation and long service life. For additional detailed information, refer to HT, HTB 700 Electronic Control Series Service Manual SM2004EN or CL(B)T 700 Series Service Manual SM1314EN and CL(B)T 755 Electronic Control Series Service Manual Supplement SM1992EN. Troubleshooting the electronic control system is presented in Troubleshooting Manual TS2712EN.
DEXRON® is a registered trademark of General Motor Corporation.
Loctite® is a registered trademark of the Loctite Corporation.
Teon® is a registered trademark of the DuPont Corporation.
Pro-Link® is a registered trademark of Micro Processor Systems, Inc.
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Model HT 741, 748 Transmission — Left-Rear View
Model HT 741, 748 Transmission — Right-Front View
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Model HT 755CR Transmission — Left-Rear View
Model HT 755CR Transmission — Right-Front View
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Model HT 755DR Transmission — Left-Rear View (With Input Retarder)
Model HT 755DR Transmission — Right-Front View (With Input Retarder)
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Model HTB 748 Transmission — Left-Front View (With Output Retarder)
Model HTB 748 Transmission — Right-Rear View (With Output Retarder)
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Model CLBT 755 Transmission — Left-Front View
Model CLBT 755 Transmission — Right-Front View
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SECTION
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Clean and inspect the exterior of the transmission at regular intervals. Severity of service and operating conditions determine the frequency of these inspections. Inspect the transmission for:
loose bolts — transmission and mounting components
uid leaks — repair immediately
loose, dirty, or improperly adjusted throttle sensor linkage
damaged or loose hoses
worn, frayed, or improperly routed electrical harnesses
worn or out-of-phase driveline U-joints and slip ttings
CAUTION: When welding on the vehicle:
DO NOT WELD on the vehicle without disconnecting from the ECU all control system wiring harness connectors.
• DO NOT WELD on the vehicle without disconnecting ECU battery power and ground leads.
• DO NOT WELD on any control components.
• DO NOT CONNECT welding cables to any control components.
A label describing on-vehicle welding precautions is available from your authorized Allison service dealer and should be installed in a conspicuous place. A vehicle used in a vocation that requires frequent modications or repairs involving welding must have an on-vehicle welding label.
Because the transmission uid cools, lubricates, and transmits hydraulic power, it is important that the proper uid level be maintained at all times. If the uid level is too low, the torque converter and clutches will not
receive an adequate supply of transmission uid, and the transmission will overheat. If the uid level is too high, the uid aerates — causing the transmission to shift erratically and overheat. Fluid may be expelled through the breather or dipstick tube when the uid level is too high.
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A severely low uid level causes the Allison Transmission Electronic Control to do two things automatically —
Turn on the CHECK TRANS light
Prevent upshifting into the highest range
When the uid level is corrected, the transmission will return to normal operation.
Do not use the Electronic Control to replace regular uid level checks. Check the level at the intervals specied in your vehicle service instructions.
WARNING: Take the following precautions so that unexpected, possible sudden vehicle movement is avoided. Whenever it becomes necessary to leave the vehicle, even momentarily, while the engine is running, place the transmission shift selector in Neutral, set the park­ing brake and/or emergency brakes and chock the wheels.
a. Fluid Check Procedure.
Clean all dirt from around the end of the ll tube before removing the dipstick. Do not allow the dirt or any foreign matter to enter the transmission. Dirt or foreign matter may cause undue wear of the
transmission parts, make valves stick, and clog passages. Check the uid level, manually, using the following procedure and record the level in your maintenance log. To perform the uid level check, the engine must be running at idle speed and the transmission must be in N (Neutral).
Add transmission uid to the transmission through the ll tube opening. Be sure to use proper transmission uid and uid containers as discussed in Sections 1–4 and 1–5. Refer to Table 1–1 for approximate transmission uid capacity.
Table 1–1. Transmission Fluid Capacity
Application U.S. Quarts Liters
41⁄2 inch (114 mm) oil pan 34 32
6 inch (152 mm) oil pan 30 28.5
7 inch (178 mm) oil pan 30 28.5
81⁄2 inch (215 mm) oil pan 43 41
NOTE: Does not include external circuits.
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b. Cold Check.
NOTE:
The purpose of the Cold Check is to determine if the transmission has enough fluid to be safely operated until a hot check can be made.
Park the vehicle on a level surface. Apply the parking brake, and chock the
wheels.
CAUTION: The uid level rises as uid temperature increases. DO NOT ll above the “COLD RUN” band if the transmission uid is below normal operating temperatures.
Run the engine for at least one minute. Shift to D (Drive) and then to
R (Reverse) to clear the hydraulic circuits of air. Then shift to N (Neutral) and
allow the engine to idle (500–800 rpm).
Insert the dipstick into the tube and remove. Check the uid level reading.
Repeat the check procedure to verify the reading.
If the uid level is within the “COLD RUN” band, the transmission may be
operated until the uid is hot enough to perform a “HOT RUN” check. If the uid level is not within the “COLD RUN” band, add or drain as necessary to bring it to the middle of the “COLD RUN” band.
Perform a hot check as soon as the normal operating temperature of
160–200°F (71–93°C) is reached.
c. Hot Check.
CAUTION: The transmission uid must be hot to ensure an accurate
check. The uid level rises as temperature increases.
Operate the transmission in D (Drive) until normal operating temperature is
reached:
160–200°F (71–93°C) sump temperature 180–220°F (82–104°C) converter-out temperature
Park the vehicle on a level surface and shift to N (Neutral). Apply the parking
brake, and chock the wheels. Allow the engine to idle.
With the engine running, remove the dipstick from the tube and wipe it clean.
Insert the dipstick into the tube and remove. Check uid level reading. Repeat
the check procedure to verify the reading.
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NOTE:
Safe operating level is within the “HOT RUN” band on the dipstick, Figure 1–1.
If the uid level is not within the “HOT RUN” band, add or drain as necessary
to bring the uid level to within the “HOT RUN” band.
d. Consistency of Readings.
Always check the uid level at least twice and with the engine running.
Consistency is important to maintain accuracy of the reading. If inconsistent reading persists, check the transmission breather to be sure it is clean and unclogged.
A
B
D
C
HOT
RUN
RUN
COLD
Figure 1–1. Typical Dipstick Markings
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CAUTION: Containers or llers that have been used for any anti­freeze or engine coolant solution must not be used for the transmis­sion uid. Antifreeze and coolant solutions contain ethylene glycol which, if introduced into the transmission, can cause the clutch plates to fail.
Transmission uid must be handled in clean containers, llers, etc., to prevent foreign material from entering the transmission. Clean around the ller tube before removing the dipstick. Lay the dipstick in a clean place while lling the transmission.
Hydraulic uids (oils) used in the transmission are important inuences on
transmission performance, reliability and durability. DEXRON®-III uid is recommended for light-duty applications. Type C-4 uids are recommended for severe-duty applications.
Some DEXRON®-III uids are also qualied as Type C-4 uids. To ensure the
uid is qualied for use in Allison transmissions, check for a DEXRON®-III or C-4 uid license, or approval numbers on the container, or consult the lubricant manufacturer. Consult your Allison Transmission dealer or distributor before using other uid types; uid types such as Type F, and universal farm uids may or may not be properly qualied for use in your Allison transmission.
CAUTION: Disregarding minimum uid temperature limits can result in transmission malfunction or reduced transmission life.
When choosing the optimum viscosity grade of uid to use, duty cycle,
preheat capabilities, and/or geographical location must be taken into consideration. Table 1–2 lists the minimum uid temperatures at which the transmission may be safely operated. Preheat with auxiliary heating equipment or by running the vehicle with the transmission in N (Neutral) for a minimum of 20 minutes before attempting range operation.
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