brakesystem.pdf 480,52 KB

BRAKE SYSTEM

1988 Jeep Cherokee

1988 BRAKES

Jeep - Brake System

Cherokee, Comanche, Grand Wagoneer, Wagoneer, Wrangler

DESCRIPTION

DISC BRAKES

Floating caliper disc brake assembly uses a single piston caliper which "floats" on 2 bolts. As brake pedal is depressed, hydraulic pressure is passed through a proportioning valve to brake caliper piston.

This force is transmitted to inboard brake pad, forcing it against braking surface of rotor. Pressure then moves outer caliper housing and pad inward on caliper mounting bolts, thus forcing outer pad against outer braking surface of rotor.

DRUM BRAKES

Self-centering type system uses primary and secondary brake shoes with cable operated automatic adjusters. Brake shoe anchor is located at upper end of shoes above wheel cylinder. Single double acting brake cylinder is used.

MASTER CYLINDER - EXCEPT GRAND WAGONEER

The Delco Quick Take-Up master cylinder is used with systems utilizing low drag calipers. Master cylinder includes a quick take-up valve which delivers a large volume of fluid, at low pressure, upon initial brake application.

MASTER CYLINDER - GRAND WAGONEER

Bendix and Delco-Moraine tandem dual piston master cylinders are single casting type with front and rear pistons and a separate reservoir and outlet for each piston. Primary piston is operated by push rod connected to brake pedal. Secondary piston is operated by primary piston.

ADJUSTMENTS

NOTE: For Hub, Bearing and Axle Shaft Removal, Installation and

Adjustment information, see appropriate DRIVE AXLES article.

DISC BRAKE PADS

Automatic adjustment is provided by outward relocation of piston as lining wears.

DRUM BRAKE SHOES

1) Rear brake shoes adjust automatically as brakes are

applied while vehicle is operated in reverse. Drive vehicle in reverse applying brakes firmly 10-15 times, between each reverse brake application, drive vehicle forward and press brakes firmly.

2) Manual adjustment is required if shoes have been removed

and reinstalled. Brake shoes can be manually adjusted by rotating adjuster screw. Remove access slot cover.

3) Using a small blade screwdriver, push in on adjustment lever to separate from adjustment screw. Turn adjustment screw until brake drum is locked tight. Back screw off until wheel rotates freely. If brake drum is to be removed, back off adjustment screw several notches for adequate clearance.

HEIGHT SENSING PROPORTIONING VALVE - COMANCHE

NOTE: Anytime adjustment is required the lever bushing must be replaced.

Adjustment must be made on a drive-on lift or a flat level surface with vehicle at curb weight. Remove height sensing proportioning valve shaft nut and washer. Disconnect valve lever and remove spring. Remove and discard bushing.

Rotate valve shaft to permit installation and proper alignment of valve adjusting gauge (J-35853-2).

NOTE: The gauge (J-35853-2) must be properly seated on the "D"

shape of the shaft and the lower mounting bolt of the valve. See Fig. 2. Also, all linkage components, excluding the spring, must be connected to the axle housing before installation of bushing.

Place lever bushing in lever. Using bushing installation tool (J-35853-1) press bushing along with lever onto valve shaft. Remove lever and adjusting to (J-35853-2) then install the spring. Install lever, washer and retaining nut. Tighten retaining nut to 100 Inch-lbs. (11 N.m). Connect spring to lever arm.

Fig. 1: Exploded View of Height Sensing Proportioning Valve


Fig. 2: Front and Side View of Valve Shaft

BACK VIEW OF VALVE

Fig. 3: Back View of Valve Shaft

PARKING BRAKE- EXCEPT GRAND WAGONEER

1) Adjust rear brakes. Check cable for binds, kinks or frayed condition. Replace cable (if necessary). Apply and release parking brake 5 times.

  1. On all models except Wrangler, place parking brake lever
    in fifth notch. Raise vehicle. Using Adjustment Gauge (J-34651), apply
    a torque of 50-55 INCH lbs. (5-6 N.m). See Fig. 4.

  2. Adjust nut on parking brake cable equalizer until pointer
    is in Blue section of gauge. Apply and release parking brake cable 5
    times. Check adjustment and readjust cable (if necessary).

Fig. 4: Parking Brake Adjustment (Except Grand Wagoneer) Courtesy of American Motors/Jeep Corp.

PARKING BRAKE - GRAND WAGONEER

  1. Adjust rear brakes. Check cable for binds, kinks or frayed
    condition. Replace cable (if necessary). Release parking brake. Loosen
    lock nuts at parking brake cable equalizer under vehicle.

  2. Tighten cables until wheels drag slightly when rotated by
    hand. Loosen equalizer until wheels rotate freely and no drag is felt.
    Tighten lock nuts and check operation of parking brake.

ROTOR SERVICING

RUNOUT

  1. Measure rotor lateral runout by mounting a dial indicator
    on support stand or steering spindle. Position indicator stylus so it
    contacts center of rotor braking surface.

  2. Zero indicator and turn rotor one revolution. Note
    indicator reading. Runout must not exceed specification. See DISC
    BRAKE ROTOR SPECIFICATIONS table. Refinish or replace rotor (if
    necessary).

NOTE: Thickness of machined rotor must not be below minimum thickness specification.

PARALLELISM

Measure rotor parallelism with a micrometer. Measure thickness at 4 or more equally spaced points around rotor at approximately 1" from edge of rotor. Variation must not exceed specification. See DISC BRAKE ROTOR SPECIFICATIONS table. Refinish or replace rotor (if necessary).

BRAKE SYSTEM BLEEDING

Hydraulic system bleeding is necessary any time air has been introduced into system. Bleed brakes at all 4 wheels if master cylinder lines have been disconnected or master cylinder has run dry. Bleed brakes with vacuum bleeding equipment, pressure bleeding equipment or by manually pumping brake pedal while using bleeder tubes. Always bleed brake lines in sequence. See BLEEDING SEQUENCE table.

MASTER CYLINDER BLEEDING

Bench Bleeding

  1. Master cylinder must be bled before installation to
    prevent excessive amounts of air from entering the brake system,
    creating poor brake operation.

  2. Place master cylinder in soft-jawed vise. DO NOT tighten
    vise enough to damage master cylinder. Install bleeder tubes in both
    outlets of master cylinder. See Fig. 5.

Fig. 5: Bleeding Master Cylinder Courtesy of American Motors/Jeep Corp.

  1. Fill master cylinder with clean brake fluid that meets DOT
    3 specifications. Ensure that the end of bleeder tubes are submerged
    in the brake fluid.

  2. Using proper sized rod, apply and release master cylinder
    until no air bubbles exist in brake fluid flow. Once all air bubbles
    are gone from master cylinder secure cap and install.

  3. Bleeder tubes should be left installed on master cylinder
    until master cylinder in installed. Master cylinder must be bled at
    brake lines and wheels after installation.

Bleeding On Vehicle

  1. Install master cylinder on vehicle after bench bleeding.
    Remove bleeder lines and install brake lines. DO NOT fully tighten
    brake lines at this time.

  2. Slowly force brake pedal to the floor and hold in this
    position. Tighten brake lines and release brake pedal. Repeat
    procedure until no air bubbles exist at brake lines. Remaining wheel
    cylinder or calipers may be require bleeding.

HYDRAULIC CONTROL VALVES

Hold Off Valve

  1. Prior to the pressure tank bleeding procedure, the hold
    off valve incorporated in the combination valve must be correctly
    positioned. This allows brake fluid to flow through the combination
    valve to the entire brake system.

  2. The valve stem of the hold off valve may be retained using

tools available from Chrysler Motors (C-4121) or General Motors (J-23709) during bleeding procedure. See Figs. 6 and 7. Remove valve retainer once brake bleeding procedure is complete.

CAUTION: DO NOT use rigid clamp to position valve stem. Damage to the valve assembly may result causing brake failure.


Fig. 6: Positioning Hold Off Valve Courtesy of American Motors/Jeep Corp.


Fig. 7: Positioning Hold Off Valve Courtesy of American Motors/Jeep Corp.

VACUUM BLEEDING

Fill master cylinder. Install vacuum bleed equipment to first bleeder valve to be serviced. Open bleeder valve 3/4-1 turn. Depress vacuum pump and pull fluid into reservoir jar. Bleed each bleeder valve in sequence. See BLEEDING SEQUENCE table.

PRESSURE BLEEDING

  1. Clean master cylinder cap and surrounding area. Remove
    cap. With pressure tank at least 1/2 full, connect to master cylinder
    with adapters. Attach bleeder hose to first bleeder valve to be
    serviced. See BLEEDING SEQUENCE table.

  2. Place other end of hose in clean glass jar partially
    filled with clean brake fluid so end of hose is submerged in fluid.
    The hold off valve must be positioned properly before pressure
    bleeding (if equipped). See HYDRAULIC CONTROL VALVES under BRAKE
    SYSTEM BLEEDING in this article.

  3. Open release valve on pressure bleeder. Follow equipment
    manufacturers pressure instructions or see PRESSURE BLEEDER SETTINGS
    table. Open bleeder screw 3/4-1 turn and note fluid flow.

  4. Close bleeder screw when fluid flowing is free of bubbles.
    Repeat procedure on remaining wheels in proper sequence. Check brake
    pedal operation after bleeding has been completed.

  5. Remove pressure bleeding equipment and valve retainer from
    hold off valve. Ensure that master cylinder is full of fluid.



MANUAL BLEEDING

NOTE: When bleeding disc brakes, air may tend to cling to caliper walls. Lightly tap caliper, while bleeding, to aid in removal of air.

  1. Fill master cylinder. Install bleeder hose to first
    bleeder valve to be serviced. See BLEEDING SEQUENCE table. Submerge
    other end of hose in clean glass jar partially filled with clean brake
    fluid. See Fig. 8.

  2. Open bleeder valve 3/4-1 turn. Depress brake pedal slowly
    through full travel. Close bleeder valve and release pedal. Repeat
    procedure until flow of fluid shows no signs of air bubbles.

NOTE: When bleeding brake system manually, ensure bleeder valve is closed when brake pedal is released.

Fig. 8: Wheel Cylinder Bleeding Procedure Courtesy of American Motors/Jeep Corp.

BLEEDING SEQUENCE

Before bleeding system, exhaust all vacuum from power unit by depressing brake pedal several times. Bleed master cylinder (if equipped) with bleeder screws. Bleed slave cylinder on vehicles equipped with remote mount power assist units. Bleed wheel cylinders and calipers in sequence. See BLEEDING SEQUENCE table.

BLEEDING SEQUENCE TABLE

Application Sequence

All Models RR, LR, RF, LF

REMOVAL & INSTALLATION

DISC BRAKE CALIPER

Removal & Installation

Caliper removal and installation procedures are same as for disc pad replacement. To remove caliper from vehicle, disconnect brake line at caliper and cap hole to prevent contamination.

DISC BRAKE PADS

Removal

  1. Drain 2/3 of brake fluid from master cylinder reservoir.
    Raise vehicle and support with safety stands. Remove front wheel
    assembly.

  2. Place "C" clamp on caliper. Solid end of clamp should
    contact back of caliper. Screw end should contact metal part of
    outboard shoes.

  3. Tighten "C" clamp until caliper forces piston to bottom of
    bore. Remove both Allen head mounting bolts and lift caliper off
    rotor. Support caliper out of the way.

  4. On Grand Wagoneer, remove both brake pads from caliper.
    Note spring position and support spring from inboard shoe. Remove
    sleeves and bushings from caliper.

  5. On all other models, hold anti-rattle clip against caliper
    adapter and remove outer brake pad. Remove inner brake pad and anti-
    rattle clip from caliper adapter.

Installation

  1. To install, reverse removal procedure. On Grand Wagoneer,
    lubricate new bushings, sleeves, bushing grooves, and small ends of
    mounting bolts with silicone lubricant. Install rubber bushings in
    caliper mounting ears.

  2. On all other models, clean caliper mating surfaces on
    adapter with a wire brush. Apply double sided adhesive tape to back
    side of inner pad. Clean caliper piston surface. Lubricate caliper
    mating surfaces on caliper adapter.

  3. On all models, lubricate caliper mounting bolts using
    brake corrosion lubricant and tighten mounting bolts. Add brake fluid
    to reservoir. Apply brakes until brake pedal is firm. Check brake
    fluid level.

DISC BRAKE ROTOR - WRANGLER

Removal

Raise and support vehicle. Remove front wheel and caliper. Suspend caliper from frame or suspension. Remove rotor from hub.

Installation

Clean hub and rotor mating surfaces. To install, reverse removal procedure.

NOTE: DO NOT disconnect brake hose from caliper unless caliper is

to be disassembled.

DISC BRAKE ROTOR - CHEROKEE, COMANCHE & WAGONEER

Removal

  1. Raise and support vehicle. Remove front wheel and caliper.
    Suspend caliper from frame or suspension. Remove cap, cotter pin, nut
    retainer, adjusting nut and thrust washer from spindle.

  2. Remove outer bearing from hub. Remove hub and rotor from
    spindle. Remove hub and rotor seal. Remove inner bearing from hub.

Installation

  1. Apply small amount of "EP" type waterproof wheel bearing
    grease in hub cavity. Lubricate inner and outer bearings. Install
    inner bearing and seal in rotor. Clean rotor surface (if necessary).

  2. Install hub and rotor on spindle. Install outer bearing,
    thrust washer and spindle nut. Tighten spindle nut to 17-25 ft. lbs.

(23-34 N.m) while rotating rotor to seat bearings. Loosen spindle nut 1/2 a turn and retighten an additional 19 INCH lbs (2 N.m). Reverse removal procedure to complete installation.

DISC BRAKE ROTOR - GRAND WAGONEER

Removal

  1. Raise vehicle and support with safety stands. Remove wheel
    and caliper. On models without front hubs, remove rotor hub cap, drive
    gear snap ring, drive gear, pressure spring and spring cup.

  2. On models with front hubs, remove screws attaching hub
    body to hub clutch and remove hub body from clutch. Remove large and
    small retaining rings. Remove hub clutch from axle shaft.

  3. On all models, remove wheel bearing outer and inner lock
    nuts and retaining ring using Socket (J-6893-D). Remove rotor. Remove
    wheel bearings from rotor.

Installation

  1. Lubricate bearings with "EP" type waterproof wheel bearing
    grease. Install bearings and seal in rotor. Install rotor and inner
    lock nut. Inner lock nut has a locating peg on one side. When
    installed, peg must face away from bearing.

  2. Install wheel, but do not tighten lug nuts completely.
    Tighten inner lock nut to 50 ft. lbs. (68 N.m) while rotating wheel.
    Back of inner lock nut 1/6 turn (45-65 degrees).

  3. Install retaining washer. Ensure that inner lock nut
    locating peg is engaged with retaining washer. Install outer lock nut
    and tighten to 50 ft. lbs. (68 N.m).

  4. On models without front hubs, install pressure spring cup,
    pressure spring, drive gear and snap ring. Coat rim of chrome hub
    cover with Permatex No. 3 and install cap in rotor hub.

NOTE: Recessed side of spring cup faces outer bearing and flat side faces pressure spring.

5) On models with front hubs, install hub clutch on axle.
Install large and small hub retaining rings. Install hub body on
clutch and tighten to 30 INCH lbs. (3 N.m). Reverse removal procedure
to complete installation.

DRUM BRAKE SHOES- EXCEPT GRAND WAGONEER

Removal

  1. Raise vehicle and support with safety stands. Remove wheel
    assembly and drum. Remove "U" clip and washer from parking brake lever
    pivot pin. Place Wheel Cylinder Clamp (J-8002) over wheel cylinder.

  2. Remove primary and secondary return springs, spring
    retainers, hold-down springs and retaining pins. Remove adjuster
    lever, adjuster screw and spring from brake shoes. Remove brake shoes.
    See Fig. 9.


Fig. 9: Exploded View of Drum Brake (W/Cable Operated Adjuster) Courtesy of American Motors/Jeep Corp.

1) Secondary Brake Shoe

2) Wheel Cylinder Pin

3) Hold Down Pin

4) Acess Cover

5) Backing Plate

6) Return Springs

7) Guide Plate

8) Adjusting Cable
9) Cable Guide

10) Washer

11) Primary Brake Shoe

12) Adjustment Lever

13) Lower Return Spring

14) Self-Adjuster

15) Parking Brake Lever

16) Parking Brake Strut

17) Parking Brake Spring

Installation

1) Lubricate support plate ledges, anchor pin, adjuster cable guide, adjuster screw assembly, parking brake lever and lever pivot pin with molybdenum disulphide grease.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  1. 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.

  2. 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.

  1. Apply grease to adjuster lever-to-secondary brake shoe
    contact surface, parking brake lever pivot and portion of lever that
    contacts secondary brake shoe.

  2. 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.

  3. Install brake shoe hold-down spring. Install return spring
    on actuating lever tang. Large end of tapered spring should rest on
    brake shoe.

  4. Install primary shoe and hold-down spring. Install guide
    plate on anchor pin. Install parking brake strut and spring on brake
    shoes.

  5. Install adjusting screw and spring. Short end of hooked
    spring attaches to primary brake shoe. Long hooked end attaches to
    secondary brake shoe.

  6. Install secondary shoe return spring, adjuster spring and
    primary return spring. Install brake drums. Adjust brakes. Bleed brake
    system.

  7. 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


Fig. 13: Exploded View of Quick Take-Up Master Cylinder Courtesy of General Motors Corp.


  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.

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

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)

BRAKE SYSTEM SPECIFICATIONS

DISC BRAKE SPECIFICATIONS

DISC BRAKE SPECIFICATIONS TABLE

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)

DRUM BRAKE SYSTEM SPECIFICATIONS

DRUM BRAKE SPECIFICATIONS TABLE

Application In. (mm)

Cherokee, Comanche, Wagoneer & Wrangler

Drum Diameter 10.00 (254.0)

Drum Width 1.75 (44.5)

Max. Drum Refinish Diam 10.06 (255.5)

Wheel Cyl. Diameter 875 (22.2)

Master Cyl. Diameter 937 (23.8)

Grand Wagoneer

Drum Diameter 11.00 (279.4)

Drum Width 2.00 (50.8)

Max. Drum Refinish Diam 11.06 (280.9)

Wheel Cyl. Diameter 937 (23.80)

Master Cyl. Diameter 1.125 (28.58)