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5 - 46 BRAKES

removal will be necessary. Remove the shoe and lining assemblies (see Brake Shoe Removal).

Combined shoe and lining thickness should be measured at the thinnest part of the assembly.

When a shoe and lining assembly is worn to a thickness of approximately 7.0 mm (9/32 inch) it should be replaced.

Replace both shoe assemblies (inboard and outboard) on both wheels whenever shoe assemblies on either side are replaced.

If a shoe assembly does not require replacement. Reinstall it, making sure each shoe assembly is returned to its original position on the wheel of the vehicle from which it was removed. (See Brake Shoe Installation).

SERVICE PRECAUTIONS

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.

Grease or any other foreign material must be kept off the caliper assembly, surfaces of the braking disc and external surfaces of the hub, during service procedures.

Handling the braking disc and caliper should be

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done in such a way as to avoid deformation of the disc and scratching or nicking the brake linings (pads).

During removal and installation of a wheel and tire assembly, use care not to strike the caliper.

Before vehicle is moved after any brake service work, be sure to obtain a firm brake pedal.

BRAKE SHOE REMOVAL

(1)Raise vehicle on jackstands or centered on a

hoist.

(2)Remove rear wheel and tire assemblies.

(3)Remove caliper attaching bolts (Fig. 2).

Fig. 2 Removing Caliper Attaching Bolts

(4) Lift caliper away from adapter rails (Fig. 3).

Fig. 3 Removing Caliper

(5) Remove outboard shoe. By prying the shoe retaining clip over the raised area on the caliper. Then slide the shoe down and off the caliper (Fig. 4).

Fig. 4 Removing Outboard Shoe

(6) Pull inboard shoe away from piston, until the retaining clip is free from the cavity in the piston. (Fig. 5).

Fig. 5 Removing Inboard Shoe

CLEANING AND INSPECTION

Check for piston seal leaks (brake fluid in and around boot area and inboard lining) and for any ruptures of piston dust boot. If the boot is damaged, or fluid leak is visible, disassemble caliper assembly and install a new seal and boot (and piston if scored). Refer to procedure titled Disassembling Caliper.

BRAKE SHOE INSTALLATION

(1)Retract piston.

(2)Install inboard brake shoe by inserting shoe retaining clip into piston cavity. Be sure brake shoe is seated squarely on the face of the piston. (Fig. 6).

Fig. 6 Installing Inboard Shoe

(3) Install outboard shoe by sliding retaining clip over caliper fingers. Be sure the brake shoe is installed on the caliper, so the retaining clip is past the raised area on the caliper fingers (Fig. 7).

Fig. 7 Installing Outboard Shoe

(4)Install lower end of caliper on to adapter. Make sure the lower tabs on the brake shoes and the casting projections on the caliper are under the adapter rail (Fig. 8).

(5)Rotate caliper down over rotor.

Fig. 8 Installing Caliper

(6) Install caliper attaching bolts and tighten to 22 NIm (193 in. lbs.) torque (Fig. 9).

Fig. 9 Installing Attaching Bolts

(7)Install wheel and tire assembly. Tighten stud nuts in proper sequence until all nuts are torqued to half specification. This is important. Then repeat sequence to full specification.

(8)Remove jackstands or lower hoist. Before moving vehicle be sure it has a firm pedal.

DISASSEMBLING REAR CALIPER ASSEMBLY

CLEANING AND INSPECTION

Check for piston fluid seal leaks (brake fluid in and around boot area and inboard lining) and for any

ruptures of piston dust boot. If boot is damaged, or fluid leak is visible, disassemble caliper assembly and install a new seal and boot, (and piston if scored). Refer to procedures titled Disassembling Caliper.

Check the caliper dust boot and caliper pin bushings to determine if they are in good condition. Replace if they are damaged, dry, or found to be brittle. Refer to Caliper Service.

(1)Remove caliper from braking disc (See Brake Shoe Removal). Hang assembly on a wire hook away from braking disc, so hydraulic fluid cannot get on braking disc (See Fig. 4 in Brake Shoe Removal). Place a small piece of wood between the piston and caliper fingers.

(2)Carefully depress brake pedal to hydraulically push piston out of bore. (Brake pedal will fall away when piston has passed bore opening.) Then prop up the brake pedal to any position below the first inch of pedal travel, this will prevent loss of brake fluid from the master cylinder.

(3)If both front caliper pistons are to be removed, disconnect flexible brake line at frame bracket after removing piston. Plug brake tube and remove piston from opposite caliper. Using the same process as above for the first piston removal.

WARNING: UNDER NO CONDITION SHOULD AIR PRESSURE BE USED TO REMOVE PISTON FROM CALIPER BORE. PERSONAL INJURY COULD RESULT FROM SUCH A PRACTICE.

(4) Disconnect brake flexible hose from the caliper. To disassemble, mount caliper assembly in a vise equipped with protective jaws.

CAUTION: Excessive vise pressure will cause bore distortion and binding of piston.

Support rear caliper assembly in a vise. Then remove caliper to piston dust boot and discard (Fig. 1).

Using a plastic trim stick, work piston seal out of its groove in caliper piston bore (Fig. 2). Discard old seal. Do not use a screwdriver or other metal tool for this operation, because of the possibility of scratching piston bore or burring edges of seal groove.

The double pin caliper uses a sealed for life bushing and sleeve assembly. If required this assembly can be serviced using the following procedure.

(1) Using your fingers push on one end the inner sleeve until it pops out of the bushing. Then grasp the inner sleeve with your fingers and pull the inner sleeve out from the inside of the bushing (Fig. 3).

Fig. 1 Removing Piston Dust Boot

Fig. 2 Removing Piston Seal

(2) Using your fingers collapse one side of the bushing. Then pull on the opposite side to remove the bushing from the caliper assembly (Fig. 4).

CLEANING AND INSPECTION

Clean all parts using alcohol or a suitable solvent and wipe dry. Clean out all drilled passages and bores on the caliper assembly body. (Whenever a caliper has been disassembled, a new boot and seal must be installed at assembly).

Inspect the caliper assembly piston bore for scoring or pitting. Bores that show light scratches or corrosion, can usually have the scratches or corrosion removed using crocus cloth.

Fig. 3 Removing Inner Sleeve From Bushing

Fig. 4 Removing Bushings From Caliper

Bores that have deep scratches or scoring should be honed. Use Caliper Hone, Special Tool C-4095, or equivalent providing the diameter of the bore is not increased more than 0.0254 mm (0.001 inch) (Fig. 5).

If the bore does not clean up within this specification, a new caliper housing should be installed. Install a new piston if the old one is pitted or scored.

Fig. 5 Honing Piston Bore

When using Caliper Honing Tool, Special Tool C-4095, coat the stones and bore with brake fluid. After honing the bore, carefully clean the seal and boot grooves with a stiff non-metallic rotary brush.

Use extreme care in cleaning the caliper after honing. Remove all dirt and grit by flushing the caliper with brake fluid; wipe dry with a clean, lint free cloth and then clean a second time.

ASSEMBLING REAR DISC BRAKE CALIPER

Clamp caliper in vise (with protective caps on vise jaws).

CAUTION: Excessive vise pressure will cause bore distortion and binding of piston.

Dip new piston seal in clean brake fluid and install in the groove of the caliper bore. Seal should be positioned at one area in groove and gently worked around the groove (Fig. 6), using only your fingers until properly seated.

NEVER USE AN OLD PISTON SEAL. (Be sure that fingers are clean and seal is not twisted or rolled) (Fig. 6).

Coat new piston boot with clean brake fluid leaving a generous amount inside boot.

Position dust boot over piston after coating with brake fluid.

Install piston into caliper bore pushing it past the piston seal until it bottoms in the caliper bore (Fig. 7).

Fig. 6 Installing New Piston Seal

Fig. 7 Pushing Piston into Bore

CAUTION: Force must be applied to the piston uniformly to avoid cocking and binding of the piston in the bore of the caliper.

Position dust boot in counterbore of the caliper piston bore.

Using a hammer and Installer Piston Caliper Boot, Special Tool C-4383-7 and Handle, Special Tool C-4171, drive boot into counterbore of the caliper (Fig. 8).

Use the following steps, to install the Guide Pin Sleeve Bushings into the caliper assembly.

(1)Fold the bushing in half lengthwise at the solid middle section of the bushing (Fig. 9).

(2)Using your fingers insert the folded bushing into the caliper assembly (Fig. 10). Do not use a sharp object to perform this step do to possible damage to the bushing.

(3)Unfold the bushing using your fingers or a wooden dowel until the bushing is fully seated into