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Remove protective paper from the noise suppression gasket and position the properly marked outboard brake shoe assembly onto the caliper (Fig. 7).

Fig. 7 Installing Outboard Shoe Assembly onto Caliper

CAUTION: Use care when installing the caliper assembly onto the steering knuckle, so the seal on the

sealed for life bushings does not get damaged.

Carefully lower caliper over braking disc and guide holddown spring under machined abutment on knuckle assembly (Fig. 8).

Fig. 8 Guiding Holddown Spring Under Machined

Abutment

Install caliper guide pin bolts and tighten to 24-34 NIm (18-25 ft. lbs.) torque. When installing guide

pin bolts, use extreme caution not to cross thread the guide pin bolts.

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.

Remove jackstands or lower hoist. Before moving vehicle be sure it has a firm pedal, pump pedal several times.

Road test vehicle and make several stops to wear off any foreign material on the brakes and to seat the linings.

DISC BRAKE CALIPER DISASSEMBLY

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. 3 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.

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

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

Remove dust boot from the brake caliper and discard (Fig. 1).

BRAKES 5 - 41

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) Push out and then pull the inner sleeve from inside of the bushing using your fingers as shown in (Fig. 3).

Fig. 1 Removing Piston Dust Boot

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.

Fig. 3 Removing Inner Sleeve

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

Fig. 4 Removing Bushings From Caliper

5 - 42 BRAKES

CLEANING AND INSPECTION OF BRAKE CALIPER

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

Inspect the piston bore for scoring or pitting. Bores that show light scratches or corrosion, can usually be cleared of the light scratches or corrosion using crocus cloth.

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).

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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. 1), 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. 1).

Fig. 5 Honing Piston Bore

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.

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 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.

Fig. 2 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.

Fig. 3 Installing Dust Boot in Caliper Counterbore

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. 4).

Fig. 4 Folded Caliper Guide Pin Bushing

(2) Using your fingers insert the folded bushing into the caliper assembly (Fig. 5). Do not use a sharp object to perform this step do to possible damage to the bushing.

Fig. 5 Installing Caliper Guide Pin Sleeve Bushings

(3) Unfold the bushing using your fingers or a wooden dowel until the bushing is fully seated into the caliper assembly. Flanges should be seated evenly on both sides of the bushing hole in the caliper assembly (Fig. 6).

Fig. 6 Bushing Correctly Installed In Caliper

Fig. 7 Installing Caliper Sleeves

Install the Guide Pin Sleeve into the guide bushing using the following procedure.

(1)Install the sleeve into one end of the bushing until the seal area of the bushing is past the seal groove in the sleeve (Fig. 7).

(2)Holding the convoluted end of the bushing with one hand. Push the sleeve through the bushing (Fig.

7)until the one end of the bushing is fully seated into the seal groove on the one end of the sleeve.

(3)Holding the sleeve in place work the other end of the bushing over the end of the sleeve and into the seal grove (Fig. 8). Be sure the other end of the bushing did not come out of the seal grove in the sleeve.

(4)When the sleeve is seated properly into the bushing. The sealed for life bushing can be held be-

Fig. 8 Installed Caliper Bushing Sleeve

tween your fingers and easily slid back and forth without the bushing seal unseating from the sleeve.

Before installing caliper assembly on vehicle, inspect braking disc. If any conditions as described in Checking Braking Disc for Runout and Thickness are present the braking disc, must be replaced or refaced. If the braking disc does not require any servicing, install caliper assembly.

Install brake hose onto caliper using banjo bolt. Torque the brake hose to caliper assembly banjo bolt to 33 NIm (24 ft. lbs.). New seal washers MUST always be used when installing brake hose to caliper.

Bleed the brake system (see Bleeding Brake System).

GENERAL INFORMATION

The rear disc brakes are similar to front disc brakes, however, there are several distinctive features that require different service procedures. This single piston, floating caliper rear disc brake assembly includes a hub assembly, adapter, braking disc (rotor), caliper, shoes and linings. The parking brake system on all vehicles equipped with rear disc brakes. Consists of a small duo-servo drum brake mounted to the caliper adapter. The drum brake shoes expand out against a braking surface (hat section) on the inside area of the braking disk (rotor).

The AC and AY body vehicles are equipped with a caliper assembly that has a 36 mm (1.42 inch) piston, and utilizes a 14 inch solid braking disc (rotor).

The AA body vehicle are equipped with a caliper assembly that uses a 34 mm (1.34 inch) piston. The AA body uses the same 14 inch solid braking disc (rotor) as on the AC and AY applications. Also available on the AA body is a caliper assembly with a 36 mm (1.42 inch) piston, with a 15 inch vented braking disc (rotor).

The AG and AJ body vehicles are also equipped with different size caliper pistons depending on the size and type of braking disk used on the vehicle. The 149 solid braking disk (rotor) applications use a 34 mm (1.34 inch) piston, and the 159 vented braking disk (rotor) applications use a 36 mm (1.42 inch) piston.

The caliper assembly on all applications float on rubber bushings using internal metal sleeves which are attached to the adapter using threaded guide pin bolts.

The adapter is mounted to the rear axle of the vehicle and is used to mount the brake shoes and actuating cables for the parking brake system. The adapter also mounts the rear caliper assembly to the vehicle. The adapter has two machined abutments which are used to position and align the caliper and brake shoes for movement for and aft (Fig. 1)

LINING WEAR

To check the amount of lining wear, remove the wheel and tire assemblies. If a visual inspection does not adequately determine the condition of the lining,