Файл: 92FWD_5.pdf

DESCRIPTION

Rear wheel drum brakes (Figs. 2 and 3) are two shoe, internal expanding type with an automatic adjuster screw assembly that is activated each time the brakes are applied. The automatic adjuster screw is located directly below the wheel cylinder as shown in figure (Figs. 2 and 3).

WARNING: DUST AND DIRT ON BRAKE PARTS GENERATED DURING THE NORMAL USE AND WEAR OF MOTOR VEHICLE BRAKE SYSTEMS CAN CONTAIN ASBESTOS FIBERS. BREATHING EXCESSIVE CONCENTRATIONS OF ASBESTOS FIBERS CAN CAUSE SERIOUS BODILY HARM, SUCH AS ASBESTOSIS AND CANCER. EXTREME CARE SHOULD BE EXERCISED WHILE SERVICING BRAKE ASSEMBLIES OR COMPONENTS.

DO NOT CLEAN BRAKE ASSEMBLIES OR COMPONENTS WITH COMPRESSED AIR OR BY DRY BRUSHING; USE A VACUUM CLEANER SPECIFICALLY RECOMMENDED FOR USE WITH ASBESTOS FIBERS. IF A SUITABLE VACUUM CLEANER IS NOT AVAILABLE, CLEANING SHOULD BE DONE WET USING A WATER DAMPENED CLOTH.

DO NOT CREATE DUST BY SANDING, GRINDING, AND/OR SHAVING BRAKE LININGS OR PADS UNLESS SUCH OPERATION IS DONE WHILE USING PROPERLY EXHAUST VENTILATED EQUIPMENT.

DISPOSE OF ALL DUST AND DIRT SUSPECTED TO CONTAIN ANY ASBESTOS FIBERS IN SEALED BAGS OR CONTAINERS TO MINIMIZE DUST EXPOSURE TO YOURSELF AND OTHERS.

FOLLOW ALL RECOMMENDED PRACTICES PRESCRIBED BY THE OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION AND THE ENVIRONMENTAL PROTECTION AGENCY. FOR THE HANDLING, PROCESSING, AND DISPOSITION OF DUST OR DIRT WHICH MAY CONTAIN ASBESTOS FIBERS.

SERVICE PROCEDURES

REAR BRAKE DRUM REMOVAL

Further clearance can be obtained by backing off the brake automatic adjuster screw. Remove rubber plug from the top of the support plate and rotate the

automatic adjuster screw assembly with an upward motion, using the Brake Adjuster, Special Tool C-3784.

See adjusting rear service brakes in the Service Adjustments section in this group of the service manual for the specific adjustment procedure.

Remove wheel bearing grease cap (Fig. 1).

Remove cotter pin, lock nut, retaining nut and washer (Fig. 1).

Remove brake drum and hub and bearing assembly from the rear spindle (Fig. 1).

Inspect brake linings for wear, shoe alignment and contamination.

Fig. 1 Brake Drum and Hub Assembly

BRAKE DRUM INSTALLATION

Install brake drum and hub and bearing assembly on rear spindle.

Install outer wheel bearing, thrust washer and nut. Tighten wheel bearing adjusting nut to 27 to 34 NIm (240 to 300 in. lbs.) torque while rotating hub.

This seats the bearings.

Back off adjusting nut 1/4 turn (90°) then tighten adjusting nut finger tight.

Position lock on nut with one pair of slots in-line with cotter pin hole. Install cotter pin.

Install grease cap and wheel and tire assemblies. Tighten wheel stud nuts to 129 NIm (95 ft. lbs.) torque on all models. Install wheel covers.

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BRAKE SHOE ASSEMBLIES

Two brake shoe assemblies are used. Vehicles will have axle sets of either Kelsey Hayes (Fig. 2), or Varga (Fig. 3). Varga brake shoes are HANDED for right or left side.

Fig. 2 Kelsey Hayes (Left) Rear Wheel Brake

Fig. 3 Varga (Left) Rear Wheel Brake

Except for shoe to anchor plate, park brake lever retention and automatic adjuster positioning guide buttons the service procedures for either assembly (except as noted) are essentially the same.

BRAKES 5 - 19

REMOVAL

Remove automatic adjuster spring and lever (Fig. 4).

Fig. 4 Remove or Install Adjuster Lever Spring

Rotate the automatic adjuster screw assembly so that each shoe assembly moves out far enough to be free from the wheel cylinder boots (Fig. 5).

Fig. 5 Expand or Retract Adjuster Screw

Disconnect the parking brake cable from the parking brake lever (Fig. 6).

Kelsey HayesÐLeading/trailing shoes; Remove holddown springs (Fig. 7). Pull assembly down and

Fig. 7 Remove or Install Holddown Springs

VargaÐLeading shoe; Remove the upper shoe to shoe return spring (Fig. 3). The leading shoe hold down spring (Fig. 7). And the shoe to shoe spring at the anchor plate (Fig. 3). Remove shoe and adjuster assembly.

VargaÐTrailing shoe; Remove holddown spring and lower shoe-to-anchor plate spring.

Kelsey Hayes: Remove park brake lever from trailing brake shoe by disengaging the retainer clip (Fig. 9). Be sure not to lose park brake lever wave washer.

Varga: Remove park brake lever from trailing brake shoe by prying retainer tangs apart. Discard retainer (Fig. 9). New retainers are provided with service kit. Be sure not to lose park brake lever wave washer.

Fig. 8 Remove or Install Brake Shoes

Fig. 9 Remove or Install Park Brake Lever Retainer

CLEANING AND INSPECTION

Clean metal portion of brake shoes. Check to see if shoes are bent.

Lining should show contact across entire width and from heel to toe, otherwise replace.

Shoes with lack of contact at toe or heel maybe improperly ground.

Clean and inspect support and adjusting screws. Apply a thin coat of Mopar Multi-Purpose Lubricant or equivalent to the threads of the self adjuster (Fig. 10). Replace adjusting screw if corroded.

Fig. 10 Adjuster Screw and Lever (Typical)

If old springs have overheated or are damaged, replace. Overheating indications are paint discoloration or distorted end coils.

BRAKE SHOE INSTALLATION

Lubricate the eight shoe contact areas on the support plate and anchor using Mopar Multi-Purpose Lubricant or equivalent (Fig. 11).

Fig. 11 Shoe Contact Areas on Support Plate

KELSEY HAYES REASSEMBLE

Assemble the park brake lever and wave washer to the new replacement shoe (Fig. 9).

Attach upper return spring between the two new shoe assemblies.

Apply a small amount of Mopar Multi-Purpose Lubricant or equivalent to the automatic adjuster screw assembly. Install adjuster with the two stepped forks facing toward the outboard side of the shoes (Fig. 10). The longer fork will be pointing to the rear.

Connect the lower shoe to shoe spring.

Expand the automatic adjuster so that the end of the shoes will clear the wheel cylinder boots. Position

the brake shoe assemblies on support plate and install holddown springs (Fig. 7).

Install self adjuster lever and spring. Connect park brake cable.

Adjust brake shoes so that they will not interfere with the drum installation.

CAUTION: Make sure the adjuster screw nut contacts the adjuster tubular strut.

Install the drums and pump the brake pedal several times to partially complete the shoe adjustment.

After adjusting the Parking brake cable (see Adjusting Parking Brake), road test vehicle. The automatic adjuster will continue the brake adjustment during the test.

VARGA REASSEMBLE

Assemble the park brake lever and wave washer to the new trailing shoe. Install retainer and close retainer ends (Fig. 9).

Install park brake cable in park brake lever of trailing shoe.

Attach trailing shoe, then leading shoe lower springs to shoes and anchor plate.

Position shoes on support plate and install holddown springs.

Install automatic adjusters. Left side adjuster has left hand threads and right side adjuster has right-hand threads. Do not interchange sides. Make sure adjuster is installed correctly. (Adjuster ends must be above extruded pins in web of shoe as shown in Fig. 3).

Install upper shoe to shoe spring. Ensure that the spring terminal ends are fully engaged in the shoe webs.

Rotate serrated adjuster nut to remove free play from the adjuster assembly.

Install the adjuster lever on the leading shoe pivot pin. Then attach the short end of the adjuster spring into the hole on the lever. Then install the long end of the spring in the leading shoe hole.

Connect park brake cable and adjust brake shoes so as not to interfere with drum installation.

BRAKE DRUM REFACING

Measure drum runout and diameter. If not to specification, reface drum. (Runout should not exceed 0.1524 mm or 0.006 inch). The diameter variation (oval shape) of the drum braking surface must not exceed either 0.0635 mm (0.0025 inch) in 30° or 0.0889 mm (0.0035 inch) in 360°.

All drums will show markings of maximum allowable diameter (Fig. 12).

Using suitable tool, remove grease seal from drum hub. Clean, inspect and pack wheel bearings. Install new seal (Fig. 13). See Wheel Bearings section in