BRAKE SYSTEM
1993 Nissan Sentra
1993 BRAKES
Nissan Disc & Drum
Sentra
DESCRIPTION & OPERATION
All brake systems are operated hydraulically using a tandem master cylinder and vacuum power unit. All models have front disc brakes. Rear brakes are either drum or disc.
BLEEDING BRAKE SYSTEM
BLEEDING PROCEDURES
NOTE: Check fluid level in master cylinder frequently during bleeding procedure.
Bleed brake system in proper sequence. See BRAKELINE BLEEDING
SEQUENCE table.
BRAKELINE BLEEDING SEQUENCE TABLE
Application |
Sequence |
Sentra ............................... |
LR, RF, RR, LF |
ADJUSTMENTS
POWER BRAKE UNIT OUTPUT ROD
1)Attach a hand-held vacuum pump to power brake unit supply port. See Fig. 1. Apply 20 in. Hg vacuum to power brake unit. Measure length of output rod extending from power brake unit housing.
2)See POWER BRAKE UNIT OUTPUT ROD LENGTH SPECIFICATIONS table. Adjust output rod length if necessary. If output rod length cannot be adjusted properly, replace power brake unit.
POWER BRAKE UNIT OUTPUT ROD LENGTH SPECS TABLE
Application |
|
In. (mm) |
Sentra 1.6L |
(8" Booster) .......... |
.19-.20 (4.8-5.1) |
Other Models |
.................... |
.40-.41 (10.3-10.5) |
Fig. 1: Measuring Output Rod Length
Courtesy of Nissan Motor Co., U.S.A.
BRAKE PEDAL HEIGHT & FREE PLAY
1)Measure pedal height from pressure face of pedal pad to floor pan insulator, without carpet. See BRAKE PEDAL HEIGHT SPECIFICATIONS table.
2)To adjust pedal height, loosen brake booster input rod lock nut, and rotate input rod to attain proper height. Tighten lock nut, and adjust stoplight switch. Ensure pedal free play is .04-.12" (1.0-3.0 mm).
BRAKE PEDAL HEIGHT SPECIFICATIONS TABLE
|
Pedal Height |
|
Application |
|
In. (mm) |
Sentra |
|
|
A/T .............................. |
6.2-6.6 |
(157-167) |
M/T .............................. |
5.8-6.2 |
(148-158) |
PARKING BRAKE
1)Remove parking brake lever cover. Raise and support rear of vehicle. Pull up on parking brake lever using force of 44 lbs. (20 kg). Rear wheels should lock at appropriate lever stroke. See PARKING BRAKE LEVER STROKE SPECIFICATIONS table.
2)Adjust parking brake using adjusting nut located beside or below parking brake lever. After releasing lever, ensure rear wheels rotate freely and slack is not present at rear cables.
PARKING BRAKE LEVER STROKE SPECIFICATIONS TABLE
Application |
Notches |
Sentra |
|
Rear Disc Brake |
................................ 7-9 |
Rear Drum Brake ................................ |
5-7 |
REAR BRAKE SHOE CLEARANCE
1)Set shoe adjustment assembly so clearance between brake drum inside diameter and brake shoes outside diameter is as specified. See BRAKE SHOE INSTALLATION CLEARANCE SPECIFICATIONS table.
2)After brake drum installation, depress brake pedal to center shoes. Check pedal travel. Rotate brake drum to verify free movement.
BRAKE SHOE INSTALLATION CLEARANCE SPECIFICATIONS TABLE
Application |
In. (mm) |
Sentra .......................... |
.014-.022 (.36-.56) |
STOPLIGHT SWITCH & AUTOMATIC SPEED CONTROL DEVICE SWITCH
1)Both switches are located below dash panel, at brake pedal bracket.Adjust brake pedal height. See BRAKE PEDAL HEIGHT & FREE PLAY.
2)Check clearance and position of switches. Clearance between brake pedal stopper rubber and threaded end of switch should be.01-.04" (0.3-1.0 mm). To adjust, loosen lock nut and turn switch body. After adjustment, tighten lock nut.
TESTING
POWER BRAKE UNIT
NOTE: Determine whether source of problem is in power brake unit or check valve. Always inspect check valve.
DO NOT disassemble power brake unit. After air-tight and operational tests, replace complete assembly if problem is determined to be in power brake unit.
Air-Tight Check
1)Start engine, and operate it for 2 minutes. Turn engine off. Depress brake pedal several times. If brake pedal height rises gradually on successive pedal depressions, go to next step. If pedal does not rise on successive pumps, check for air leak.
2)Start engine. Depress brake pedal and turn engine off. Hold brake pedal down for 30 seconds. If brake pedal height does not change, power brake unit is air tight. If pedal height changes, check for air leak.
Operational Check
With engine off, depress brake pedal several times until pedal height no longer changes. Press and hold brake pedal down. Start engine. If pedal goes down slightly, power brake unit is okay. If pedal does not move, check for air leak.
PROPORTIONING VALVE
CAUTION: Check rear brake pressure 2 seconds after front brake pressure reaches specified value. On vehicles with ABS, disconnect ABS actuator harness connector.
Using 2 pressure gauges, attach one to front brake bleeder and one to rear brake bleeder. Bleed air from front and rear bleeders. Depress brake pedal until front brake pressure reading is achieved. Check rear brake pressure. See PROPORTIONING VALVE PRESSURE SPECIFICATIONS table. If reading is not as indicated, replace dual proportioning valve (separated type) or master cylinder assembly (built-in type).
PROPORTIONING VALVE PRESSURE SPECIFICATIONS TABLE
|
|
Front Brake Pressure |
Rear Brake Pressure |
||
Application |
psi (kg/cm ) |
psi (kg/cm ) |
|||
Sentra |
|
|
|
|
|
With ABS |
|
|
|
|
|
Except 2.0L (SE) |
.......... 711 |
(50) ............ |
284-341 (20-24) |
||
2.0L |
(SE) ................. |
924 |
(64) ............ |
498-555 |
(34-38) |
Without ABS |
|
|
|
|
|
1.6L |
...................... |
1067 (75) ........... |
640-697 |
(45-49) |
|
2.0L |
(SR) ................. |
782 |
(55) ............ |
356-412 |
(25-29) |
2.0L |
(SE) ................. |
995 |
(70) ............ |
569-626 |
(40-44) |
REMOVAL & INSTALLATION
NOTE: When removing or installing components, refer to appropriate illustration for exploded view of specific assembly. See Figs. 2-4.
FRONT BRAKE PADS
Removal
1)Raise and support front of vehicle. Remove wheel assembly. Remove bottom guide pin. Rotate caliper body upward on guide pin.
2)Remove pad retainers, shims and brake pads. Note pad condition and location for proper installation (if reusable). Minimum pad thickness is .08" (2.0 mm) for all models.
Installation
1)Clean piston and area around lock and guide pins. Install inner pad. Seat piston by placing lever through opening in caliper body and pushing piston into bore. Apply brake grease to pad retainer points on caliper assembly. Install outer pad and shims.
2)Install pad retainers. Rotate caliper body down into original position. Install lower lock pin. Tighten bolts to specification, and depress brake pedal several times to seat pads. See TORQUE SPECIFICATIONS table at the end of this article.
FRONT BRAKE CALIPER
Removal
Raise and support front of vehicle. Remove wheel assembly. Disconnect and plug brake line from caliper. Remove caliper mount bolts. Remove caliper assembly.
Installation
To install, reverse removal procedure. Tighten caliper mount
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