Disc & Drum Ford Bronco II I

ANTI-LOCK BRAKE SYSTEM (BRONCO II)

Bronco II models are equipped with a Rear Wheel Anti-Lock Brake System (RABS). This system is designed to prevent vehicle from skidding due to rear brake lock up. This is done by controlling the amount of hydraulic fluid pressure to the rear wheel cylinders. For more information about this system, see ANTI-LOCK BRAKE SYSTEM article in the BRAKES Section.

BRAKE BOOSTER VACUUM PUMP (DIESEL)

Vacuum is supplied to brake booster on diesel engine models by belt driven vacuum pump mounted on engine near alternator. A low-vacuum switch actuates the brake warning light when vacuum is below a specified level.

The switch senses vacuum through a fitting in the intake manifold that intercepts the vacuum flow from the pump. Brake warning light will illuminate until vacuum builds to proper level.

Vacuum pump is not serviceable and must be replaced if found defective. For diagnosis, see BRAKE BOOSTER VACUUM PUMP under DIAGNOSIS.

BRAKE SYSTEM BLEEDING

Brake system bleeding is necessary any time air has been introduced into brake system. Bleed brakes at all four wheels if master cylinder lines have been disconnected or master cylinder has run dry.

Bleeding may be done either by using pressure bleeding equipment or by manually pumping brake pedal and using bleeder tubes. After bleeding, pressure differential control valve must be centered.

BRAKE WARNING LIGHT SYSTEM

When parking brake is disengaged, the brake warning light should only illuminate when ignition switch is in START position or when fluid level in master cylinder reservoir is low.

DISC BRAKES

All models use a single piston caliper. On all models, caliper is secured to caliper mounting fixture by 2 caliper retaining pins. Ventilated rotor is cast together with wheel hub.

DRUM BRAKES

Single anchor dual servo brake assembly is used on all trucks. Assembly consists of support plate, 2 brake shoes, return springs, automatic adjuster components and wheel cylinder.

Automatic adjuster consists of cable (with hood and anchor fitting), cable guide, adjusting lever, adjusting screw, pivot nut, socket and spring.

Adjuster uses movement of secondary shoe during reverse brake application to turn brake adjusting screw. Lining-to-drum clearance is automatically maintained during service life of linings.

MASTER CYLINDER

Ford dual piston is a conventional master cylinder with front and rear pistons and a plastic reservoir with an outlet for braking circuit. Integral with the plastic reservoir is a fluid level indicator. It consists of a float, magnet assembly and reed switch. When brake fluid drops below a predetermined level, the magnet attached to the float actuates the reed switch, causing the warning light to illuminate.

Rear wheels are connected to secondary outlet ports and are actuated by secondary piston assembly. Front wheels are connected to primary outlet port (nearest dash panel) and are actuated by the primary piston assembly. On some vehicles vacuum assist booster is not standard equipment.

POWER BRAKE BOOSTER

The Bendix Single Diaphragm booster is a vacuum supended unit which uses engine manifold vacuum on one side of diaphragm and atmospheric pressure on the other. The vacuum power chamber consists of a front and rear shell, diaphragm, diaphragm plate, push rod, and vacuum diaphragm return spring.

A mechanically actuated power brake unit check valve, integral with the vacuum power diaphragm, controls the degree of brake application and release in accordance with foot pressure applied to check valve operating rod through brake pedal linkage. Only the booster check valve is a serviceable component. The single diaphragm dash-mounted booster is non-repairable.

MASTER CYLINDER BLEEDING

Note. Master cylinder can be bled on vehicle or by using bench bleeding method.

On Vehicle Bleeding

1. Loosen one line nut on master cylinder. Wrap shop cloth around tubing below fitting to absorb escaping brake fluid. Depress brake pedal to floor by hand and hold. Tighten fitting.
2. Release brake pedal. Do not release pedal until fitting is tightened or air will re-enter master cylinder. Repeat procedure until air no longer escapes from master cylinder. Repeat process for other line(s) and ensure that brake pedal is firm.

Bench Bleeding

1. Clamp master cylinder in vise by mounting flange. Install plugs in outlet ports. Fill reservoir with clean brake fluid. Loosen plug in rear port. Slowly depress piston slowly to force air from cylinder. Without releasing piston, tighten plug in outlet port.
2. Repeat process until no air is released from port. Bleed front outlet port(s) using same method until all air is removed from cylinder.

MANUAL BLEEDING

Note. DO NOT allow master cylinder to run dry during bleeding. NEVER reuse brake fluid that has drained from brake system. When bleeding disc brakes, air may tend to cling to caliper walls. Lightly tap caliper while bleeding to aid in removal of air.

1. Attach bleeder hose to right rear wheel cylinder and submerge end of hose in container partially filled with clean brake fluid. Loosen fitting about 3/4 turn and slowly depress brake pedal fully. Close bleeder and release brake pedal. Repeat until fluid is free of air bubbles.
2. Repeat process following bleeding sequence. See «BLEEDING SEQUENCE»(/ford/bronco-ii/i-1984-1990/remont/mechanical-hydraulic/#disc-drum) . Bronco II models are equipped with Anti-Lock Brake System (ABS), ABS valve must be bled after rear wheels. After completing bleeding procedure ensure brake pedal is firm.

PRESSURE BLEEDING

Note. NEVER reuse brake fluid that has drained from brake system. Ensure bleeder tank has sufficient fluid to complete bleeding procedure. DO NOT exceed 50 psi of pressure in tank.

1. On power brake equipped vehicles, release vacuum from booster by depressing brake pedal several times. 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 right rear wheel cylinder.
2. Place other end of hose in clean container partially filled with clean brake fluid so end of hose is submerged in fluid. Open release valve on pressure bleeder. Follow equipment manufacturers pressure instructions unless noted below.
3. Unscrew bleeder valve 3/4-1 turn noting fluid flow. When fluid flowing from cylinder to jar is free of bubbles, close bleeder valve securely. Repeat process following bleeding sequence. See «BLEEDING SEQUENCE»(/ford/bronco-ii/i-1984-1990/remont/mechanical-hydraulic/#disc-drum) . Bronco II models are equipped with Anti-Lock Brake System (ABS), ABS valve must be bled after rear wheels. After completing bleeding procedure ensure brake pedal is firm.

PRESSURE BLEEDER SETTINGS

BLEEDING SEQUENCE

BLEEDING SEQUENCE

BRAKE PEDAL

Brake pedal adjustments are not required. Brake pedal free-travel will not be correct if power brake booster push rod clearance is not correct. See POWER BRAKE BOOSTER PUSH ROD under ADJUSTMENTS.

Scheme 1

Scheme 2

1. Adjustment is made with brake drums cold and parking brakes correctly adjusted. Measure inside diameter of brake drum with brake shoe adjustment gauge. (Scheme 1)
2. Reverse adjustment gauge. Apply gauge to brake shoes on a line parallel to ground and through center of axle. Hold automatic adjuster lever away from adjusting screw. Turn screw until outside diameter of shoes contacts gauge. (Scheme 2)
3. Install brake drum and wheel assembly. Complete adjustment by applying brakes several times while driving vehicle in reverse. Check brake operation by making several stops while driving forward.

DISC PADS

Pad wear is automatically compensated for by piston sliding outward in cylinder bore. No disc pad adjustment is required. On all "E" and "F" 250 thru 350 series, including 4WD, replace linings if thickness is less than 1/32" (.79 mm). Replace pads if lining thickness is less than 1/16" (1.5 mm) on all other vehicles. Always replace both sets of brake pads. Never service one wheel only.

PARKING BRAKE (AEROSTAR)

Note. Aerostar parking brake system is self-adjusting and requires no periodic adjustment. If any parking brake system component needs to be removed, parking brake cable tension must be released.

Scheme 3

1. Remove boot cover from parking brake control lever. Place control lever in released position. Insert a steel pin through pawl lock-out pin hole. (Scheme 3)
2. Insert pin from inboard side at a slightly upward and forward angle and sweep downward and rearward to move self-adjusting pawl. This procedure locks out self-adjusting pawl.
3. Raise vehicle with helper inside on hoist. Pull rearward on equalizer about 1-2 1/2" (25.4-57.1 mm), rotating self-adjuster reel backward.
4. With equalizer pulled rearward, have helper inside vehicle insert a steel pin through self-adjusting spring lock-out holes in lever arm and lever body, locking ratchet wheel in cable released position.

Resetting Cable Tension

Connect parking brake cables to equalizer. Remove steel pin from spring lock-out hole, keeping fingers clear. Remove steel pin from pawl lock-out hole, restoring tension to parking brake cable. Apply and release parking brake several times to set cable tension.

Scheme 4

1. Parking brake control assembly spring tension is lost when coil spring unwinds and disengages from tab on wheel. This occurs when a cable breaks, when servicing system without inserting lock pin or if lock pin is removed before brake cables are connected.
2. Remove parking brake control lever assembly. Hook end of coil spring on wheel tab. (Scheme 4) Insert a steel pin through pawl lock-out pin holes. Insert pin from inboard side at a slightly upward and forward angle and sweep downward and rearward to move self-adjusting pawl. This procedure locks out self-adjusting pawl.
3. Slip a spare front cable around pulley. Insert cable anchor pin into pivot hole in ratchet plate assembly. With cable on floor, place foot on cable, or clamp end of cable in a vise.
4. Pull on brake control assembly, holding mounting bracket tightly against body of control assembly. Pull until cable tension rotates cable track in order to fully insert lock pin. Insert lock pin so control assembly is in released position. Install parking brake control lever assembly.

PARKING BRAKE (EXCEPT AEROSTAR)

Note. If front brake cable tension limiting device is replaced, initial adjustment procedures must be performed before adjusting cable. If tensioner is not replaced, initial adjustment is not required.

Initial Adjustment

Depress parking brake pedal. Grip tension limiter bracket to prevent it from spinning. Tighten equalizer nut 2 1/2" up the rod. Ensure cinch strap has slipped so that less than 1 3/8" of strap remains exposed.

Final Adjustment

1. Adjust service brakes before adjusting parking brake cable. Ensure brake drums are cold.
2. Position parking brake pedal to fully depressed position. Grip tension limiter housing to prevent it from spinning. Tighten equalizer nut 6 full turns past its original position.
3. Check cable tension at rear of equalizer assembly using Cable Tension Gauge (021-00018). Tension should be 400-600 lbs. (182-272 kg). If tension is not to specification, repeat step 2).
4. Release pedal and check rear wheel drag. If drag is noted, remove drums and check for clearance between parking brake lever and cam plate.
5. Clearance should be .015" (.38 mm) with brakes fully released. If clearance is not to specification, readjust parking brake cable.

POWER BRAKE BOOSTER PUSH ROD

Check distance from outer end of push rod to front face of unit using a locally manufactured gauge. (Scheme 5) Turn push rod screw in or out until length is.980"-.995" (24.9-25.3 mm).

Scheme 5

VACUUM PUMP DRIVE BELT TENSION (DIESEL)

1. Loosen alternator pivot bolt and alternator tab bolt. Lift up on alternator until specified tension is obtained. See «VACUUM PUMP BELT TENSION SPECIFICATIONS»(/ford/bronco-ii/i-1984-1990/remont/mechanical-hydraulic/#disc-drum) .
2. When specified tension is reached, tighten alternator tab bolt to 24-34 ft. lbs. (32-46 N.m) and alternator pivot bolt to 38-53 ft. lbs (52-72 N.m).

VACUUM PUMP BELT TENSION SPECIFICATIONS (DIESEL)

WHEEL BEARINGS (2WD)

1. Raise vehicle until tire clears floor. Remove wheel cover. Remove grease cap from the hub. Wipe excess from end of spindle. Remove cotter pin and retainer.
2. Loosen adjusting nut 3 turns. Obtain running clearance between rotor brake surface and shoe lining by rocking entire wheel assembly in and out several times to push caliper and brake pads away from rotor.
3. An alternate method to obtain the proper running clearance may be done by lightly tapping on the caliper housing. Be sure not to tap on any other area that may damage the rotor and the lining surfaces. DO NOT pry on the phenolic caliper piston.
4. The running clearance must be maintained throughout bearing adjustment procedure. If proper clearance cannot be maintained, caliper must be removed.
5. While rotating wheel assembly, tighten adjusting nut to 17-25 ft. lbs. (23-34 N.m). Loosen adjusting nut 1/2 turn. Retighten to 18-20 INCH lbs. (2.0-2.3 N.m).
6. Place retainer on adjusting nut. The castellations on the retainer must be aligned with cotter pin hole in the spindle. DO NOT turn adjuster nut to make castellations line up with hole in spindle.
7. Remove retainer from the nut and re-index retainer without moving nut. Repeat until castellations line up with hole in spindle. Install a new cotter pin. Check front wheel rotation. If wheel rotates properly, reinstall the grease cap and wheel cover.
8. If rotation is noisy or rough, remove, inspect and lubricate the bearing cones and cups. Before driving the vehicle, pump the brake pedal several times to restore normal brake travel.

Scheme 6

1. Raise vehicle and install safety stands. Remove wheel lug nuts and remove wheel and tire assembly. Remove retainer washers from lug nut studs and remove automatic locking hub assembly from spindle.
2. Remove snap ring from end of spindle shaft. Remove axle shaft spacer, needle thrust bearing and bearing spacer. Being careful not to damage plastic moving cam, pull cam assembly off wheel bearing adjusting nut and remove thrust washer and needle thrust bearing from adjusting nut. NOTE: To prevent damage to spindle threads, look into spindle keyway under adjusting nut hole and remove any portion of locking key that has been separated from cam assembly before removing adjusting nut. If this condition exists, do not re-use. Discard entire cam assembly and replace with Service Kit (1A053).
3. Loosen wheel bearing adjusting nut from spindle using a 2-3/8" hex socket. While rotating hub and rotor assembly, tighten wheel bearing adjusting nut to 35 ft. lbs. (47 N.m) to seat bearings, then back off nut 1/4 turn.
4. Retighten adjusting nut to 16 in. lbs. (1.8 N.m) using a torque wrench. Align closest hole in wheel bearing adjusting nut with center of spindle keyway slot. Advance nut to next hole if required. CAUTION: Extreme care must be taken when aligning spindle nut adjustment hole with center of spindle keyway slot to prevent damage to cam assembly locking key.
5. Install lock nut needle bearing and thrust washer in order of removal. Push or press cam assembly onto lock nut by lining up key in fixed cam with spindle keyway. Install bearing thrust washer, needle thrust bearing and axle shaft spacer.
6. Clip snap ring onto end of spindle. Install automatic locking hub assembly over spindle by lining up 3 legs on hub assembly with 3 pockets in cam assembly. Install retainer washers. Install wheel and tire assembly. Install and tighten lug nuts. Final end play of wheel on spindle should be .001-.003" (.02-.08 mm).

WHEEL BEARINGS (4WD W/MANUAL LOCKING HUBS

1. Raise the vehicle and support with safety stands. Remove wheel lug nuts and remove the wheel and tire. Remove retainer washers from the lug studs and remove the manual locking hub from the spindle.
2. Remove the axle shaft spacer, needle thrust bearing and the bearing spacer. Remove the outer wheel bearing lock nut from the spindle using Four-Prong Spindle Nut Spanner Wrench (T83T-1197-A). Ensure the tabs on the wrench engage the slots in the lock nut.
3. Remove the lock nut washer from the spindle. Loosen the inner wheel bearing lock nut using spanner wrench. Ensure that the tabs of the wrench engage the slots in the lock nut and that the slot in the wrench is over the pin on the lock nut.
4. Tighten the inner lock nut to 35 ft. lbs. (47 N.m) to seat the bearings. Spin the rotor and back-off the inner lock nut 1/4 turn. Install the lock washer on the spindle. It may be necessary to turn the inner lock nut so the pin on the lock nut aligns with the closest hole in the lock washer.
5. Install the outer wheel bearing lock nut using spanner wrench. Tighten lock nut to 150 ft. lbs (203 N.m). Install the bearing thrust spacer, needle bearing and axle shaft spacer.
6. Clip the snap ring onto the end of the spindle. Install the manual hub over the spindle. Install the retainer washers. Install the tire and wheel and tighten lug nuts to specification.
7. Check the end play of the wheel and tire on the spindle. End play should be 0.001-0.003" (0.02-0.08 mm). Install locking hub.

Scheme 7

LATERAL RUNOUT

1. Tighten spindle nut to eliminate bearing end play. Ensure that rotor can be turned. Install and tighten lug nuts. Attach dial indicator on suspension, with indicator tip on face of rotor.
2. Set dial indicator to zero, slowly turn rotor, and note high and low readings on dial. Runout must not exceed specifications. Resurface or replace rotor as required. Cuts must be of equal depth on both sides of rotor.

PARALLELISM

Using a micrometer, measure rotor thickness at 12 points approximately 30 degrees apart, and at 1" (25 mm) from outer edge of rotor. Difference must not exceed specifications. Resurface or replace rotor as required.

Scheme 8

1. Block wheels and apply parking brake. Disconnect low vacuum switch (if equipped). Place automatic transmission in Park or manual transmission in Neutral. Start and run engine at idle. Disconnect vacuum pump hose from brake booster and install vacuum gauge. (Scheme 8)
2. Minimum vacuum gauge reading should be 21 in. Hg at sea level, within 30 seconds. For higher altitudes, compensate vacuum reading according to graph. (Scheme 8) If vacuum reading is correct, go to step 4).
3. If vacuum reading is low or fluctuating, check gauge and connections for leaks. If pump is belt driven, check belt tension and pulley fit to shaft. Check idle speed. Recheck vacuum pump. If vacuum reading is still low, replace vacuum pump. If vacuum pump is now okay, go to next step.
4. Reconnect vacuum hose with a "T" fitting and vacuum gauge located near pump inlet. (Scheme 9) With engine idling, vacuum may be 3 in. Hg less than that measured in step 1).
5. If vacuum reading is correct, remaining problems are not in vacuum system. If vacuum reading is lower than specified, check hoses for leaks and repair as necessary. If vacuum reading is still low, check vacuum accessories for leaks. Repair or replace as necessary.

Scheme 9

Note. On models equipped with diesel engine, brake warning light will illuminate until proper vacuum level is built up by vacuum pump. Ensure vacuum level is reached before testing brake warning light system.

1. When parking brake is disengaged, the brake warning light should only be on when ignition switch is in the START position or when brake fluid level is low. Turn ignition switch to START position. If warning lamp does not illuminate, check bulb and wiring and repair as necessary.
2. If warning light does not light when brake fluid level is low, check bulb, fluid level switch in reservoir and switch to lamp wiring. Repair as necessary. On Bronco II and Ranger, push float to bottom of brake fluid reservoir. Light should illuminate. If light does not light, replace reservoir assembly.

Removal

1. Remove wheel assembly and drum. Place a clamp over ends of wheel cylinder. Disengage adjusting lever from adjusting screw by pulling backwards on lever.
2. Move outboard side of adjusting screw up. Back off pivot nut as far as possible. Pull adjusting lever, cable and automatic adjuster spring down and toward rear to unhook pivot hook from large hole in secondary shoe. Do not pry pivot hook from hole.
3. Remove automatic adjuster spring and adjusting lever. Remove shoe-to-anchor springs, cable anchor and anchor pin plate. (Scheme 10)
4. Remove cable guide, shoe hold-down springs, shoes adjusting screw, pivot nut and socket. Remove parking brake spring and link. Note color and position of springs for reassembly.
5. Disconnect parking brake cable from lever. Remove secondary shoe. Disassemble parking brake lever from shoe by removing retaining clip and spring washer.

Installation

To install, reverse removal procedure. Ensure adjusting cable is in groove of cable guide. Cable must not bind on anchor pin. Ensure adjuster screw has been mounted on correct side. If adjuster screw is mounted on wrong side, adjuster will operate incorrectly.

Scheme 10

1. To prevent master cylinder overflow when caliper piston is depressed, remove a small amount of brake fluid from master cylinder. Raise vehicle and support with safety stands.
2. Remove front wheel assembly. Place a large "C" clamp on caliper. Tighten clamp to bottom piston in cylinder bore. Remove clamp.
3. Remove dirt from around caliper pin tabs. Tap upper caliper pin toward inboard side of vehicle, until pin tabs touch spindle face.
4. Insert a screwdriver into slot provided behind pin tabs on inboard side of pin. Using pliers, compress end of pin while prying with screwdriver until tabs slip into spindle groove.
5. Place a 7/16" punch on end of pin and drive caliper pin out of caliper slide groove. Repeat procedure for lower pin. Remove caliper from rotor. Remove outer brake pad. Compress anti-rattle clip and remove inner brake pad. Support caliper out of the way.

1. Reverse removal procedure. Ensure that outer shoe torque tabs are solidly seated in caliper cut-outs. Install caliper pin until retention tabs on side of pin contact spindle face.
2. Do not allow tabs of caliper pin to be tapped in too far into spindle groove. If this happens, it will be necessary to tap the other end of pin until tabs snap into place. To complete installation, reverse removal procedure.
3. Install new anti-rattle clip on lower end of inner pad. Place lower end of pad in spindle, with clip against pad, and clip loop away from rotor. Slide upper end of pad into position. Be sure clip is still in position.
4. With piston fully bottomed in cylinder bore, position outer pad on caliper and press pad tabs into place. If pad cannot be pressed into place by hand, use a large "C" clamp. To complete installation, reverse removal procedure. Bleed air from brake system if required. Apply brakes until a firm pedal is obtained.

Removal & Installation

Raise vehicle and support with safety stands. Remove wheel and caliper assemblies. Remove dust cap, cotter pin, nut, washer and outer bearing. Carefully remove hub and rotor assembly. Remove inner bearing and seal. To install, reverse removal procedure. Adjust front wheel bearings. See appropiateWHEEL BEARINGS under ADJUSTMENTS .

1. Raise vehicle and support with safety stands. Remove wheel assembly and caliper. Remove retainer washers from lug nut studs. Remove locking hub assembly. See appropiate LOCKING HUBS under «REMOVAL & INSTALLATION»(/ford/bronco-ii/i-1984-1990/remont/mechanical-hydraulic/#disc-drum__removal-installation) . Remove snap ring from end of spindle shaft.
2. Remove axle shaft spacer, needle bearing, and bearing spacer. Being careful not to damage plastic moving cam, pull cam assembly off wheel bearing adjustment nut. Remove thrust washer and thrust (needle) bearing from adjustment nut.
3. Look into spindle keyway, under adjustment nut hole. Remove locking key before removing adjustment nut. Remove adjustment nut using Socket (T7OT-4252-B). Remove hub and disc assembly. Outer wheel bearing will slide out as hub is being removed.
4. Remove grease seal and inner wheel bearing. Inspect needle and wheel bearings for wear or damage. Inspect bearing cups for pits or cracks. Replace worn parts. If necessary, remove bearing cups with drift.

1. Pack needle and wheel bearings. Install inner wheel bearing and grease seal. Install hub and disc assembly on spindle. Install outer wheel bearing and adjustment nut.
2. Spin rotor and tighten adjustment nut to 35 ft. lbs. (47 N.m). Back off nut 1/4 turn. Retighten adjustment nut to 16 in. lbs. (1.8 N.m). Carefully align closest hole in adjustment nut with center of spindle keyway. NOTE: Extreme care must be taken when aligning nut with center of spindle keyway to prevent damage to cam assembly locking key.
3. Install thrust (needle) bearing and thrust washer. Install cam assembly onto lock nut by lining up key in cam with spindle keyway. Install bearing spacer, needle bearing, and axle shaft spacer.
4. Install snap ring. End play should be .001"-.003" (.025-.076 mm). Install locking hub assembly on spindle. Reverse removal procedure to complete installation.

1. Raise vehicle and support with safety stands. Remove wheel assembly and caliper. Remove retainer washers from lug nut studs. Remove locking hub assembly from spindle. See appropiate LOCKING HUBS under «REMOVAL & INSTALLATION»(/ford/bronco-ii/i-1984-1990/remont/mechanical-hydraulic/#disc-drum__removal-installation) .
2. Remove snap ring from end of spindle shaft. Remove axle shaft spacer, needle bearing and bearing spacer. Remove wheel bearing outer lock nut using Front Wheel Bearing Spanner (T38T-1197-A).
3. Remove lock nut washer. Remove wheel bearing inner lock nut using spanner. Remove hub and disc assembly. Slide out outer wheel bearing hub is being removed.
4. Remove grease seal and inner wheel bearing. Inspect needle and wheel bearings for wear or damage. Inspect bearing cups for pits or cracks. Replace worn parts. If necessary, remove bearing cups with drift.

1. Pack needle and wheel bearings. Install inner wheel bearing and grease seal. Install hub and disc assembly on spindle. Install outer bearing and inner lock nut. Tighten lock nut to 35 ft. lbs. (47 N.m).
2. Spin rotor and back off inner lock nut 1/4 turn. Install lock washer. It may be necessary to turn inner lock nut slightly so that pin on lock nut aligns with closest hole on lock washer.
3. Install outer lock nut and tighten to 150 ft. lbs. (203 N.m). Install bearing spacer, needle bearing, and axle shaft spacer. Install snap ring. End play should be .001"-.003" (.025-.076 mm). Reverse removal procedure to complete installation.

1. Raise vehicle and install safety stands. Remove wheel lug nuts and remove wheel and tire assembly. Remove retainer washers from lug nut studs and remove automatic locking hub assembly from spindle.
2. Remove snap ring from end of spindle shaft. Remove axle shaft spacer, needle thrust bearing and bearing spacer. Being careful not to damage plastic moving cam, pull cam assembly off wheel bearing adjusting nut and remove thrust washer and needle thrust bearing from adjusting nut.

Note. To prevent damage to spindle threads, look into spindle keyway under adjusting nut hole and remove any portion of locking key that has been separated from cam assembly before removing adjusting nut. If this condition exists, do not re-use. Discard entire cam assembly and replace with Service Kit (1A053).

1. Adjust wheel bearing. See appropiateWHEEL BEARINGS under «ADJUSTMENTS»(/ford/bronco-ii/i-1984-1990/remont/mechanical-hydraulic/#disc-drum) . Install lock nut needle bearing and thrust washer in order of removal. Push or press cam assembly onto lock nut by lining up key in fixed cam with spindle keyway. Install bearing thrust washer, needle thrust bearing and axle shaft spacer.
2. Clip snap ring onto end of spindle. Install automatic locking hub assembly over spindle by lining up 3 legs on hub assembly with 3 pockets in cam assembly. Install retainer washers. Install wheel and tire assembly. Install and tighten lug nuts. Final end play of wheel on spindle should be .001-.003" (.02-.08 mm).

1. Raise vehicle and install safety stands. Remove wheel lug nuts and remove wheel and tire assembly. Remove retainer washers from lug nut studs and remove manual locking hub assembly.
2. To remove internal hub lock assembly from outer body assembly, remove outer lock ring seated in hub body groove. Internal assembly, spring and clutch gear will now slide out of hub body. DO NOT remove screw from plastic dial. Rebuild hub assembly in reverse order of disassembly.

Scheme 11

Install manual locking hub assembly over spindle and place retainer washers on lug nut studs. Install wheel and tire assembly. Install lug nuts and tighten to specification.

Disconnect brake warning light indicator wire from plastic reservoir fluid level indicator. With engine off, depress brake pedal to expel vacuum from brake booster. Disconnect brake lines at master cylinder. Remove nuts retaining master cylinder to brake booster. Remove master cylinder.

To install, reverse removal procedure. Center pressure differential valve and bleed system. See BRAKE SYSTEM BLEEDING .

Removal (Ranger)

1. Disconnect brake warning indicator light wire from plastic reservoir socket. From inside cab below instrument panel, disconnect wires from stoplight switch.
2. Remove retaining pin, spacers, and bushing securing master cylinder push rod to brake pedal. Remove stoplight switch from pedal. Disconnect brake lines from master cylinder.
3. Remove nuts securing master cylinder to firewall. Remove bolts and studs securing master cylinder to firewall and remove master cylinder. Remove boot and master cylinder push rod.

To install, reverse removal procedure. Center pressure differential valve and bleed system. See BRAKE SYSTEM BLEEDING .

1. Disconnect stop light switch to prevent discharging battery. Support master cylinder. Remove nuts securing master cylinder.
2. Loosen clamp that secures vacuum hose to power brake unit check valve and remove hose. Remove check valve. Pull master cylinder off power brake unit, far enough away to allow removal of power brake unit.
3. From inside cab, remove pin, spacers, and bushing securing push rod and stop light switch to brake pedal. Remove nuts securing power brake unit and remove.

1. Prior to installing power brake unit ensure that booster rubber reaction disc is properly installed. (Scheme 12) If the master cylinder push rod is removed or accidentally pulled out, a dislodged disc may cause excessive pedal travel.
2. The reaction disc is Black, compared to the Silver valve plunger that will be exposed if push rod and seat are removed. To install power brake unit, reverse removal procedure. Start engine and check for proper brake operation.

Note. Booster must be replaced if reaction disc cannot be properly installed and aligned, or if it cannot be located within the unit itself.

Scheme 12

1. Raise vehicle and support with safety stands. Remove wheel assembly and brake drum. Loosen differential cover plate. Drain lubricant from axle. Remove cover plate and discard gasket.
2. Remove differential pinion shaft lock bolt (lock pin). Discard lock bolt (pin). Remove differential pinion shaft. Push flanged end of axle toward center of vehicle and remove "C" clip from end of shaft. Do not lose or damage "O" ring (if equipped) under "C" clip.
3. Pull axle shaft from axle tube. Ensure oil seal is not damaged during removal. When removing axle shaft, do not rotate differential side gears. Rotating side gears causes pinion gears and thrust washers to fall out.
4. Insert Slide Hammer (T50T-100-A) and Axle Bearing Remover (T85L-1225-AH) behind bearing. Remove seal and bearing as a unit.

1. Lubricate bearing with axle lubricant and install bearing using Axle Tube Bearing Replacer (T78P-1225-A). Lubricate lips of seal with multipurpose grease. Install seal with Seal Replacer (T78P-1177-A).
2. Install axle shaft. Ensure splined shaft engages side gears. Push flanged end of axle shaft toward center of axle and install "C" clip. Pull axle shaft outward until "C" clip locks into side gear.
3. Install pinion shaft. Ensure hole in shaft is lined up with hole in case. Ensure pinion thrust washers are in position. Ensure threads in case and lock screw are free of dirt and oil.
4. Install new lock bolt (lock pin). Tighten lock bolt to 20-25 ft. lbs. (27-34 N.m). Add RTV or silicone sealer to cover plate. Install plate. Reverse removal procedure to complete installation.

Remove wheel assembly, drum and brake shoes. Remove cylinder connecting links. Disconnect hydraulic brake line from cylinder. Remove brake cylinder retaining bolts. Remove cylinder from backing plate. To install, reverse removal procedure. Adjust brakes and bleed hydraulic system.

Scheme 13

1. Remove caliper. Remove plug from inlet port (if used) and drain fluid from cylinders. Place a block of wood between caliper and cylinders. (Scheme 13) Apply low air pressure to brake hose inlet. Air pressure will force out piston(s).
2. If a piston is jammed or cocked and will not easily come out, tap end of piston sharply with a brass hammer to straighten. Do not pry piston from bore.
3. Reapply low air pressure to remove cocked piston. Remove seal and boot from grooves. Discard seals and boots.

Cleaning & Inspection

1. Clean rust and corrosion from caliper machined surfaces with a wire brush, being careful not to get wire brush in cylinder bores. Clean all components with denatured alcohol and dry with compressed air.
2. Inspect cylinder bore, seal grooves, and boot grooves for wear or damage. If bores are scored, corroded or worn, replace caliper. Replace anti-rattle clip, caliper support spring and key.

Scheme 14

Reassembly

1. Lubricate piston seal with clean brake fluid and install in cylinder bore groove. Lubricate cylinder with clean brake fluid. Coat piston and outside beads of dust boot with clean brake fluid.
2. Push piston through boot until boot is around bottom (closed end) of piston. Position piston and boot directly over cylinder bore. Work bead of dust boot into groove near top of cylinder bore.
3. With bead seated in groove, press straight down on piston until it bottoms in cylinder bore. Care must be taken not to cock or jam piston in cylinder. If necessary use a "C" clamp and a block of wood to bottom piston in cylinder.

Note. Manufacturer does not recommend honing of cylinder bore. Disassembly

1. Remove master cylinder. Clean outside of master cylinder. Remove filler cap and diaphragm. Drain any remaining fluid from cylinder. Depress primary piston and remove snap ring from end of master cylinder bore.
2. Remove primary piston assembly from cylinder bore. Apply air pressure in forward outlet port of cylinder, carefully removing secondary piston assembly from bore. Using large screwdriver, carefully pry plastic reservoir from master cylinder body (if equipped).

Inspection

Clean all parts with isopropyl alcohol, and blow dry with compressed air. Ensure that all ports and vents are open and free of foreign matter. Inspect master cylinder bore and all parts for excessive wear or damage. If bore is damaged, replace master cylinder.

1. Lubricate all components including cylinder bore with clean brake fluid. Install new grommets and plastic reservoir (if equipped). Carefully insert secondary and primary piston assemblies into master cylinder bore. Depress primary piston and install snap ring in groove.
2. On vehicles with manual brakes, install push rod retainer onto push rod and install into primary piston. Ensure that retainer is properly seated and holding push rod securely.

Bleeding

1. Support master cylinder in a vise and fill both reservoirs with Dot 3 brake fluid. Install plugs in brake outlet ports. Loosen plug in rear outlet port and depress primary piston slowly to force air out of cylinder. Tighten plug while piston is depressed to prevent air from entering cylinder.
2. Repeat procedure until no air bubbles are present in exiting fluid. Proceed to front outlet port when rear is bled, ensuring that rear plug is tight. Piston travel will be greatly restricted when all air is expelled. Remove plugs. Install cover and diaphragm.

Scheme 15

Scheme 16

The power brake unit is serviced as an assembly and must be replaced if it is found to be defective. The unit must also be replaced if the rubber reaction disc (Black) cannot be properly aligned, installed, or if it cannot be located within the unit. (Scheme 17)

Scheme 17

Disassembly

With wheel cylinder removed from vehicle, remove rubber boots from ends of cylinders. Remove piston return spring, cylinder cups and piston from cylinder. Remove bleeder screw. Inspect cylinder bore for damage.

If bore of cylinder is lightly pitted or scratched, hone or replace as necessary. Soak all parts in brake fluid or assembly lube. To assemble, reverse disassembly procedures. Clamp brake cylinder pistons against ends of cylinder.

TORQUE SPECIFICATIONS

TIGHTENING SPECIFICATIONS

DISC BRAKE SPECIFICATIONS

DISC BRAKE SPECIFICATIONS

DRUM BRAKE SYSTEM SPECIFICATIONS

DRUM BRAKE SPECIFICATIONS

See also:
• BRAKE BOOSTER VACUUM PUMP
• POWER BRAKE BOOSTER PUSH ROD
• REMOVAL & INSTALLATION