Front Disc Brake Caliper
DISC BRAKE CALIPER FRONTREMOVAL
1. Depress the brake pedal past its first inch of travel and hold it in this position using a brake pedal depressor (holding) tool. This is done to isolate the master cylinder from the brake hydraulic system disallowing the brake fluid to completely drain out of the brake fluid reservoir.
2. Raise the vehicle. .
3. Remove front wheel and tire assembly.
4. Remove the anti-rattle spring from the outboard side of the caliper and adapter (Fig. 23).
5. Remove the banjo bolt connecting the brake hose to the brake caliper (Fig. 24). There are two washers (one on each side of the brake hose fitting) that will come off with the banjo bolt. Discard these washers.
6. Remove the two caps in place over the caliper guide pin bolts (Fig. 24).
7. Remove the two caliper guide pin bolts (Fig. 25).
8. Remove caliper from caliper adapter and brake rotor. The outboard shoe will probably stay with the caliper adapter while the inboard shoe will come off with the caliper as the caliper is removed.
DISASSEMBLY - CALIPER GUIDE PIN BUSHINGS (DISC/DISC BRAKES)
Before disassembling the brake caliper, clean and inspect it.
1. Using your fingers, collapse one side of the rubber guide pin bushing. Pull the guide pin bushing out the other side of the brake caliper mounting boss.
2. Repeat this procedure on the remaining bushing.
DISASSEMBLY- CALIPER PISTON AND SEAL
WARNING: UNDER NO CONDITION SHOULD HIGH PRESSURE AIR EVER BE USED TO REMOVE A PISTON FROM A CALIPER BORE. PERSONAL INJURY COULD RESULT FROM SUCH A PRACTICE.
NOTE: Before disassembling the brake caliper, clean and inspect it.
NOTE: The safest way to remove the piston from the caliper bore is to use the hydraulic pressure of the vehicle's brake system.
1. Following the removal procedure in DISC BRAKE SHOES, remove the caliper from the brake rotor and hang the assembly on a wire hook away from rotor and body of the vehicle so brake fluid cannot get on these components. Remove the brake shoes, and place a small piece of wood between the piston and caliper fingers.
2. Carefully depress the brake pedal to hydraulically push piston out of its bore. Once completed, apply and hold down the brake pedal to any position beyond the first inch of pedal travel using a brake pedal holding tool. This will prevent the fluid in the master cylinder reservoir from completely draining out.
3. Disconnect the brake fluid flex hose from the caliper assembly and remove it from the vehicle.
CAUTION: Do not use excessive force when clamping caliper in vise. Excessive vise pressure will cause bore distortion.
4. Mount the caliper in a vise equipped with protective jaws.
5. Remove the piston dust boot from the caliper and discard (Fig. 26).
NOTE: Do not use a screw driver or other metal tool for seal removal. Using such tools can scratch the bore or leave burrs on the seal groove edges.
6. Using a soft tool such as a plastic trim stick, work the piston seal out of its groove in caliper piston bore (Fig. 27). Discard the old seal.
7. Clean the piston bore and drilled passage ways using alcohol or a suitable solvent. Wipe it dry using only a lint-free cloth.
8. 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.
CLEANING
WARNING: DUST AND DIRT ACCUMULATING ON BRAKE PARTS DURING NORMAL USE MAY CONTAIN ASBESTOS FIBERS FROM PRODUCTION OR AFTERMARKET BRAKE LININGS. BREATHING EXCESSIVE CONCENTRATIONS OF ASBESTOS FIBERS CAN CAUSE SERIOUS BODILY HARM. EXERCISE CARE WHEN SERVICING BRAKE PARTS. DO NOT SAND OR GRIND BRAKE LINING UNLESS EQUIPMENT USED IS DESIGNED TO CONTAIN THE DUST RESIDUE. DO NOT CLEAN BRAKE PARTS WITH COMPRESSED AIR OR BY DRY BRUSHING. CLEANING SHOULD BE DONE BY DAMPENING THE BRAKE COMPONENTS WITH A FINE MIST OF WATER, THEN WIPING THE BRAKE COMPONENTS CLEAN WITH A DAMPENED CLOTH. DISPOSE OF CLOTH AND ALL RESIDUE CONTAINING ASBESTOS FIBERS IN AN IMPERMEABLE CONTAINER WITH THE APPROPRIATE LABEL. FOLLOW PRACTICES PRESCRIBED BY THE OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION (OSHA) AND THE ENVIRONMENTAL PROTECTION AGENCY (EPA) FOR THE HANDLING, PROCESSING, AND DISPOSING OF DUST OR DEBRIS THAT MAY CONTAIN ASBESTOS FIBERS.
To clean or flush the internal passages of the brake caliper, use fresh brake fluid or Mopers Non-Chlorinated Brake Parts Cleaner. Never use gasoline, kerosene, alcohol, oil, transmission fluid or any fluid containing mineral oil to clean the caliper. These fluids will damage rubber cups and seals.
INSPECTION
Inspect the disc brake caliper for the following:
^ Brake fluid leaks in and around boot area and inboard lining
^ Ruptures, brittleness or damage to the piston dust boot
^ Damaged, dry or brittle guide pin dust boots
If caliper fails inspection, disassemble and recondition caliper, replacing the seals and dust boots.
ASSEMBLY - CALIPER GUIDE PIN BUSHINGS (DISC/DISC BRAKES)
1. Fold the guide pin bushing in half lengthwise.
NOTE: To avoid damage to the bushing, do not use a sharp object to install the guide pin bushing.
2. Insert the folded bushing into the caliper mounting boss using your fingers from the rear of the caliper.
3. Unfold the bushing using your fingers or a wooden dowel until the bushing is fully seated into the caliper housing. The bushing flanges should be seated evenly on both sides of the bushing hole.
4. Lubricate inside surfaces of bushing using Mopers Dielectric Grease or equivalent.
5. Repeat the procedure for remaining bushing.
ASSEMBLY- CALIPER PISTON AND SEAL
NOTE: Never use an old piston seal.
1. Dip the new piston seal in clean brake fluid and install it in the groove of the caliper bore. The seal should be started at one area of the groove and gently worked around and into the groove (Fig. 28) using only your clean finders to seat it.
2. Coat the new piston boot with clean brake fluid leaving a generous amount inside the boot.
3. Position the dust boot over the piston after coating it with brake fluid.
CAUTION: Force applied to the piston to seat it in the bore must be applied uniformly to avoid cocking and binding of the piston.
4. Install piston into caliper bore pushing it past the piston seal until it bottoms in the caliper bore (Fig. 29).
5. Position the dust boot into the counterbore of the caliper assembly piston bore.
6. Using a hammer and Installer, Special Tool C-4689 or C-4842 (depending on piston size), and Handle, Special Tool C-4171, drive the boot into the counterbore of the caliper as necessary (Fig. 30).
7. Reinstall the caliper on the vehicle and bleed the brakes as necessary.
INSTALLATION
1. Completely retract the caliper piston back into piston bore of the caliper.
2. Lubricate both caliper adapter abutments where the shoes slide with a sufficient amount of Mopers Dielectric Grease, or equivalent.
NOTE: If shoes are being transferred or newly installed, make note that the inboard brake shoes are stamped L or R for left or right side of the vehicle. The P-slot or void on piston insulator must be positioned upward when brake caliper is mounted (Fig. 31).
CAUTION: Use care when installing the brake caliper assembly onto the adapter, so that the seals on the caliper guide pin bushings do not get damaged by the adapter bosses.
3. Carefully position the brake caliper (with inboard shoe) over the brake rotor, outboard shoe and adapter. For proper positioning of shoes when installing caliper, Refer to BRAKE PADS/SHOES - INSTALLATION.
4. Install the caliper guide pin bolts and tighten to a torque of 35 Nm (26 ft. lbs.) (Fig. 25). Extreme caution should be taken not to cross thread the caliper guide pin bolts.
5. Install the caps over the ends of the guide pin bolts (Fig. 24).
6. Install the anti-rattle spring on the outboard side of the caliper (Fig. 23). Start the clip into the holes on the caliper, then stretch the clip legs past the abutments on the caliper adapter.
CAUTION: When connecting the brake hose to the caliper, install new brake hose to caliper special washers.
7. Install the brake hose on the caliper. To do this, first place one NEW special fitting washer on each side of the hose fitting, then slide the banjo bolt through the fitting. Next, thread the banjo bolt into the threaded port on the rear of the brake caliper (Fig. 24). Tighten the banjo bolt to a torque of 35 Nm (26 ft. lbs.).
8. Install the wheel and tire assembly. Tighten the wheel mounting stud nuts in proper sequence until all nuts are torqued to half specification, then repeat the tightening sequence to the full specified torque of 135 Nm (100 ft. lbs.).
9. Lower the vehicle.
10. Remove the brake pedal depressor (holding) tool.
11. Bleed the hydraulic brake circuit to the brake caliper.
12. Road test the vehicle and make several stops to wear off any foreign material on the brakes and to seat the brake shoe linings.