1988 JEEP CHEROKEE Service Repair Manual

guide, adjuster screw assembly, parking brake lever and lever pivot
pin with molybdenum disulphide grease.
2) Connect parking brake lever to secondary brake shoe with
washer and "U" clip. Crimp ends of clip to secure clip on pivot.
Remove wheel cylinder clamp. Position brake shoes on brake support
plate and install hold-down springs.
3) Install parking brake lever strut and spring. Install
adjuster cable guide plate and adjuster cable on anchor pin. Install
primary return spring. Install guide to secondary brake shoe. Install
secondary return spring.
4) Install adjuster screw, spring and lever. Connect lever to
cable. Using Brake Gauge (J-21177-01), preset brake shoe adjustment.
Install brake drums. Adjust brake shoes with drum in place.
5) Install wheels and lower vehicle. To adjust and balance
brake system, apply and release brakes 10-15 times while driving
forward and backward. Road test vehicle.
DRUM BRAKE SHOES - GRAND WAGONEER
Removal
1) Raise vehicle and support with safety stands. Remove
wheels. On models with full-floating rear axle, remove 2 screws that
retain drum on hub.
2) On all models, remove primary shoe return spring,
automatic adjuster actuator spring and secondary shoe return spring.
Remove hold-down springs. Remove brake shoe assemblies. See Fig. 10.
3) Disengage parking brake cable from parking brake lever.
Remove parking brake strut and brake shoe assembly as a unit. Place
wheel cylinder clamps over cylinders in order to retain pistons.
4) Inspect automatic adjuster lever and pivot, actuating
lever, parking brake lever, automatic adjuster and springs. Replace
weak springs, bent levers and parts that are worn or broken.
Fig. 10: Exploded View of Drum Brake Assembly (Grand Wagoneer)
Courtesy of American Motors/Jeep Corp.
Installation
1) Clean support plate. Apply a thin film of molybdenum

disulphide grease or chassis lubricant on support plate ledges, anchor
pin, adjuster screw threads and pivot.
2) Apply grease to adjuster lever-to-secondary brake shoe
contact surface, parking brake lever pivot and portion of lever that
contacts secondary brake shoe.
3) Attach parking brake cable to parking brake lever on
secondary shoe. Pinch "U" clip to retain lever on shoe. Install
secondary brake shoe, automatic adjuster lever and lever pivot as an
assembly.
4) Install brake shoe hold-down spring. Install return spring
on actuating lever tang. Large end of tapered spring should rest on
brake shoe.
5) Install primary shoe and hold-down spring. Install guide
plate on anchor pin. Install parking brake strut and spring on brake
shoes.
6) Install adjusting screw and spring. Short end of hooked
spring attaches to primary brake shoe. Long hooked end attaches to
secondary brake shoe.
7) Install secondary shoe return spring, adjuster spring and
primary return spring. Install brake drums. Adjust brakes. Bleed brake
system.
8) Install wheels and lower vehicle. Apply and release brakes
10-15 times while driving forward and backward to adjust and balance
brake system. Road test vehicle.
MASTER CYLINDER - EXCEPT GRAND WAGONEER
Removal
1) With engine off, depress brake pedal several times to
release vacuum in power unit. Clean dirt and grease from brake line
connections.
2) Disconnect and plug brake lines at master cylinder. Remove
retaining nuts and master cylinder.
Installation
To install, reverse removal procedure. Bleed brake system.
See BRAKE SYSTEM BLEEDING in this article.
MASTER CYLINDER - GRAND WAGONEER
Removal
Disconnect brake lines at master cylinder and plug. On
vehicles without power assist units, disconnect brake pedal push rod
at brake pedal. Remove master cylinder retaining nuts at firewall.
Remove master cylinder.
Installation
1) Master cylinder should be bench bled before installation.
See BRAKE SYSTEM BLEEDING in this article. Position master cylinder on
vehicle. Loosely install retaining nuts. Loosely install brake lines
to cylinder. Tighten retaining nuts. Tighten brake lines.
2) Connect brake pedal push rod (if removed). Fill reservoir\
with brake fluid and bleed brake system. See BRAKE SYSTEM BLEEDING in
this article.
REAR AXLE BEARING & SEAL
Removal
1) Raise vehicle and support with safety stands. Remove wheel
assembly and brake drum. Remove support plate retaining nuts through
hole provided in axle flange. Use a slide hammer to remove axle shaft.
2) If wheel bearing cup remains in housing, use Slide Hammer
(J-2619-01) and Bearing Remover (J-26941) to remove bearing cups.

Remove axle shaft oil seal from axle housing tube.
3) Place axle shaft in a vise. Drill a 1/4" (6.35 mm) hole
3/4 of the way through bearing retaining ring. Chisel off bearing
retaining ring. Do not use a torch. Press bearing off axle. Remove
seal and retainer plate.
Installation
Lubricate bearing and seal lip. Install retainer plate and
seal over axle. Press axle shaft bearing and retaining ring on shaft
simultaneously. Ensure bearing and ring are seated against axle shaft
shoulder. To complete installation, reverse removal procedure to
complete installation.
WHEEL CYLINDER
Removal
Remove wheel assemblies, brake drums and brake shoes.
Disconnect brake line at wheel cylinder. Do not bend brake line away
from cylinder. Remove cylinder-to-support plate bolts. Remove
cylinder.
Installation
To install, reverse removal procedure. Start brake line
fitting into cylinder before installing cylinder to support plate.
OVERHAUL
DISC BRAKE CALIPER
Disassembly
1) Clean caliper exterior with brake cleaning solvent. Drain
residual fluid from caliper and place caliper on a clean working
surface.
2) Remove piston from caliper by applying compressed air to
inlet port. Use just enough pressure to ease piston out of bore.
Protect piston from damage with folded shop towels. Do not try to
catch piston by hand.
3) Pry dust boot out of bore with screwdriver. Do not scratch
bore. Using a small plastic or wooden stick, pry piston seal from
bore. See Fig. 11. Remove bleeder screw, sleeves, and bushings.
Cleaning & Inspection
Clean all parts with brake cleaning solvent. Blow dry parts.
Check for damaged or worn parts. Stains on piston bore can be polished
with crocus cloth. Do not use emery cloth or any other abrasive.
Reassembly
1) Lubricate bore and new seal with brake fluid. Install seal
in groove using fingers. Lubricate piston with brake fluid. Slide
metal retainer portion of dust boot over open end of piston. Pull boot
rearward until boot lip seats in piston groove.
2) Push retainer portion of dust boot forward until boot is
flush with rim at open end of piston and boot fold snaps into place.
Insert piston in bore being careful not to unseat piston seal.
3) Push piston to bottom of bore using hammer handle.
Position dust boot retainer in counterbore at top of piston bore. Seat
dust boot retainer with Dust Boot Installer (J-22904 or J-33028).
Reverse removal procedure to complete installation.

Fig. 11: Caliper Assembly (Grand Wagoneer)
Courtesy of American Motors/Jeep Corp.
Fig. 12: Caliper Assembly (Except Grand Wagoneer)
Courtesy of American Motors/Jeep Corp.
MASTER CYLINDER - EXCEPT GRAND WAGONEER

NOTE: Do not hone master cylinder. Bore has a highly polished
"Bearingized" surface. Honing will cause premature failure
of rubber parts.
Disassembly
1) Remove reservoir cover and diaphragm. Drain remaining
brake fluid. Push in on primary piston and remove snap ring.
2) Carefully apply compressed air at forward brake line hole
while plugging rear hole. Use caution as piston will be forced out
open end of master cylinder with considerable force.
3) Remove spring retainer and seals from secondary piston.
Discard seals. Clamp mounting ear of master cylinder in vise and
carefully pry off reservoir.
4) Do not attempt to remove take-up valve from master
cylinder as it is not a serviceable component. Remove reservoir
grommets and discard.
Inspection
Inspect cylinder bore for scoring or corrosion. If signs of
corrosion are evident, replace master cylinder. Use no abrasives on
cylinder bore. Inspect reservoir cover and diaphragm for cuts, cracks
or deformation. Replace damaged or defective parts as necessary.
Reassembly
1) Lubricate new reservoir grommets with clean brake fluid
and press into master cylinder. Ensure grommets are properly seated.
Lay reservoir on flat, hard surface. Rock master cylinder body onto
reservoir until completely seated.
2) Lubricate new piston seals with clean brake fluid and
install on secondary piston, with lip of seals toward ends of piston.
Install spring retainer.
3) Install secondary piston spring and secondary piston
assembly in master cylinder. Lubricate primary piston seals with clean
brake fluid.
4) Install primary piston in master cylinder. Press in piston
and install snap ring. Fit diaphragm in reservoir cover and install
cover.
Fig. 13: Exploded View of Quick Take-Up Master Cylinder
Courtesy of General Motors Corp.

MASTER CYLINDER - GRAND WAGONEER
NOTE: Do not hone master cylinder bore. Bore has a highly polished
"bearingized" surface. Honing will cause premature failure
of rubber parts.
Disassembly
1) Clean outside of cylinder thoroughly and remove cover.
Drain fluid. Pump piston to remove any remaining fluid. On
Delco/Moraine models with composite fluid reservoir, install metal
flange in vise and pry reservoir off with a pry bar. Bendix composite
reservoir is held on by 4 bolts on bottom of reservoir. On manual
brake models, remove boot from cylinder to uncover push rod retainer.
2) Pry up retainer tab to release retainer. Remove snap ring
from groove in cylinder bore. Remove both piston assemblies. Remove
remaining internal parts from bore. Note direction of piston seals.
Remove and discard all rubber parts from piston assemblies.
3) Tube seats can be removed if damaged. Enlarge holes in
tube seats using a 13/64" drill. Place a large flat washer over outlet
and thread a 1/4" x 20 x 3/4" screw into seat. Tighten screw until
seat is loose. See Fig. 14. Remove seat, screw and washer.
Fig. 14: Removing Tube Seat from Master Cylinder
Courtesy of American Motors/Jeep Corp.
Inspection
Inspect cylinder bore for scoring or corrosion. Staining

which has not pitted or roughened surface of cylinder can be removed
with crocus cloth. If cylinder bore is scored, pitted or corroded,
replace master cylinder.
Reassembly
1) Install replacement tube seats by threading a spare brake
line tube nut into hole. Turn nut in until tube seat bottoms. Do not
cock tube seat in hole. Remove nut and check for burrs which may have
been loosened by nut. Install secondary seals on secondary piston,
with cup lips facing away from each other.
2) Install primary seal, spring retainer and return spring on
secondary piston. Install seal so lip faces interior of master
cylinder when installed. Lubricate cylinder bore with clean brake
fluid and install secondary piston assembly. Lubricate primary piston
seals and install primary piston assembly in bore. Hold primary piston
downward in bore and install snap ring.
3) Install composite reservoir (if equipped). On models with\
push-on composite fluid reservoir, invert reservoir, install grommets
and press on body using a rocking motion. Install master cylinder
cover and new diaphragm.
4) On vehicles with manual brakes, assemble brake pedal push
rod through retainer (if equipped). Push retainer over end of master
cylinder and install rubber boot.
Fig. 15: Exploded View of Master Cylinder (Grand Wagoneer)
Courtesy of American Motors/Jeep Corp.
WHEEL CYLINDER

Disassembly
Remove dust boots. Push pistons, piston cups and expander
spring out of bore. Discard cups. Clean all parts with brake solvent.
Inspect cylinder bore and piston for pitting, wear or damage. Replace
as necessary. Light scoring or pitting may be removed by honing.
Reassembly
1) Lubricate cylinder bore and internal components with brake
fluid. Do not lubricate dust boots. Position replacement piston cups
on spring expanders. Install assembled parts in cylinder bore.
2) Ensure expanders are seated in piston cups. Cups are to be
installed with lips facing each other. Install pistons with flat sides
facing interior of bore. Install dust boots.
TORQUE SPECIFICATIONS
TORQUE SPECIFICATIONS TABLE








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Application Ft. Lbs. (N.m)
Disc Brakes
Caliper Mounting Bolts ......................... 35 (47)
Bleeder Screw .................................. 12 (16)
Brake Line-to-Caliper .......................... 13 (18)
Drum Brakes
Wheel Cylinder Bolts ........................... 11 (15)
Bleeder Screw 1/4" ........................... 4-5 (5-7)
Bleeder Screw 3/8" ......................... 4-10 (5-14)
Brake Line ............................... 10-17 (14-23)
Backing Plate Bolt ....................... 30-40 (41-54)
Master Cylinder Retaining Nuts
Except Grand Wagoneer .......................... 20 (27)









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BRAKE SYSTEM SPECIFICATIONS
DISC BRAKE SPECIFICATIONS
DISC BRAKE SPECIFICATIONS TABLE








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Application In. (mm)
Cherokee, Comanche, Wagoneer & Wrangler
Disc Diameter ............................ 11.02 (279.9)
Lateral Runout ............................ 0.005 (0.13)
Parallelism ............................... 0.001 (0.03)
Original Thickness ......................... 0.88 (22.4)
Min. Refinish Thickness .................. 0.815 (20.70)
Discard Thickness ........................ 0.815 (20.70)
Grand Wagoneer
Disc Diameter ............................ 12.00 (304.8)
Lateral Runout ............................ 0.005 (0.13)
Parallelism ............................... 0.001 (0.03)
Original Thickness ................................. N/A
Min. Refinish Thickness .................. 1.215 (30.86)
Discard Thickness ........................ 1.215 (30.86)









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DRUM BRAKE SYSTEM SPECIFICATIONS
DRUM BRAKE SPECIFICATIONS TABLE