AMC Coupes/Sedans/Wagons 1975-1988 Repair Information

Brake Caliper

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REMOVAL, INSTALLATION, OVERHAUL 1975-81 Models



EXCEPT PACER
  1. Raise the front of the car and remove the front wheels.
  2.  
  3. Working on one side at a time only, disconnect the brake hose from the steel brake line and cap the fittings. Remove the U-shaped retainer from the hose fitting (if it has one).
  4.  
  5. Remove the caliper mounting bolts (locating pins) and positioners and lift the caliper away from the disc.
  6.  
  7. Clean the holes in the caliper ears, and wipe all dirt from the mounting bolts. If the bolts are corroded or damaged they should be replaced.
  8.  
  9. Remove the shoe support springs from the piston.
  10.  
  11. Remove the rubber bushings from the grooves in the caliper ears.
  12.  
  13. Remove the brake hose, drain the brake fluid, and clean the outside of the caliper.
  14.  
  15. Pad the inside of the caliper with towels and direct compressed air into the brake fluid inlet hole to remove the piston.
  16.  


CAUTION
To prevent damage to the piston use just enough air pressure to ease it out of the bore. Do not attempt to catch or protect the piston with your hand since this may cause serious injury.

  1. Use a prytool to pry the boot out of the caliper. Avoid scratching the bore.
  2.  
  3. Remove the piston seal from its groove in the caliper bore. Do not use a metal tool of any type for this operation.
  4.  
  5. Blow out all passages in the caliper and bleeder valve. Clean the piston and piston bore with fresh brake fluid.
  6.  
  7. Examine the piston for scoring, scratches, or corrosion. If any of these conditions exist the piston must be replaced, as it is plated and cannot be refinished.
  8.  
  9. Examine the bore for the same defects. Light rough spots may be removed by rotating crocus cloth, using finger pressure, in the bore. Do not polish with an in and out motion or use any other abrasive. Piston-to-bore clearance should be 0.002-0.006 in. (0.051-0.152mm).
  10.  

To install:
  1. Lubricate the piston bore and the new rubber parts with fresh brake fluid. Position the seal in the piston bore groove.
  2.  
  3. Lubricate the piston with brake fluid and assemble the boot into the piston groove so that the fold faces the open end of the piston.
  4.  
  5. Insert the piston into the bore, taking care not to unseat the seal.
  6.  
  7. Force the piston to the bottom of the bore. (This will require a force of 50-100 lbs.). Seat the boot lip around the caliper counterbore. Proper seating of the boot is very important for sealing out contaminants.
  8.  
  9. Install the brake hose into the caliper using a new copper gasket.
  10.  
  11. Lubricate the rubber bushings. Install the bushings in the caliper ears.
  12.  

Lubrication of the bushings is essential to ensure the proper operation of the sliding caliper design.

  1. Install the shoe support spring in the piston.
  2.  
  3. Install the disc pads in the caliper and remount the caliper on the hub. Refer to the disc brake pad removal and installation procedure in this section.
  4.  


WARNING
Clean, high quality brake fluid is essential to the safe and proper operation of the brake system. You should always buy the highest quality brake fluid that is available. If the brake fluid becomes contaminated, drain and flush the system, then refill the master cylinder with new fluid. Never reuse any brake fluid. Any brake fluid that is removed from the system should be discarded.

  1. Reconnect the brake hose to the steel brake line. Install the retainer clip. Bleed the brakes.
  2.  
  3. Replace the wheels, check the brake fluid level, check the brake pedal travel, and road test the vehicle.
  4.  

PACER
  1. Remove the caliper as outlined under Steps 1-7 of the disc brake pad removal and installation procedure in this section.
  2.  
  3. Place a clean piece of paper on your work area to put the parts of the caliper on while it is being disassembled.
  4.  
  5. Drain the brake fluid from the caliper by opening the bleeder plug.
  6.  
  7. Place the caliper assembly in a vise with padded jaws.
  8.  


WARNING
Do not overtighten the vise; too much pressure will cause distortion of the caliper bore.

  1. Using compressed air, remove the piston from the caliper bore. Be careful not to damage the piston or the bore. Leave the dust boot in the caliper groove while the piston is being removed.
  2.  
  3. Take the caliper out of the vise and withdraw the dust boot.
  4.  
  5. Work the piston seal out of its groove in the piston bore with a small, pointed wooden or plastic stick. Do not use a screwdriver or other metallic tool to remove the seal as it could damage the bore. Throw the old seal away.
  6.  
  7. Unscrew the bleeder plug.
  8.  
  9. Clean all of the parts in brake fluid (do not use solvent) and wipe them dry with a clean, lint free cloth. Dry the passages and bores with compressed air.
  10.  

Check the cylinder bore for scoring, pitting, and/or corrosion. If the caliper bore is deeply scored or corroded, replace the entire caliper.

If it is only lightly scored or stained, polish with crocus cloth. Use finger pressure to rotate the crocus cloth in the cylinder bore. Any black stains found in the bore are caused by seals and are harmless.


WARNING
Do not slide the crocus cloth in and out of the bore. Do not use any other type of abrasive material.

Check the piston. If it is pitted, scored, or worn, it should be replaced with a new one.

Check the piston-to-bore clearance with a feeler gauge. It should be 0.002-0.006 in. (0.051-0.152mm). If it is more than this, replace the caliper assembly.

To install:
  1. Dip a new piston seal in clean brake fluid. Position the seal in one area of the groove in the cylinder bore and gently work it into place around the groove until it is seated. Be sure that your fingers are clean before touching the seal.
  2.  

Never reuse an old piston seal.

  1. Coat a new piston boot with clean brake fluid. Work it into the outer groove of the bore with your fingers until it snaps into place. Don't worry if the boot seems too large for the groove; once seated, it will fit properly. Check the boot, by running your forefinger around the inside of it, to be sure that it is correctly installed.
  2.  
  3. Coat the piston with plenty of brake fluid. Spread the boot with your fingers and insert the piston into it.
  4.  
  5. Depress the piston until it bottoms in the bore.
  6.  


WARNING
Apply uniform force to the piston or it will crack.

  1. Install the caliper assembly as outlined under Steps 9-15 of the disc brake pad removal and installation procedure.
  2.  

1982-86 Models See Figure 1

Click image to see an enlarged view

Fig. Fig. 1: Pad the inside of the caliper with towels and use compressed air to remove the caliper piston

  1. Drain and discard 2 / 3 of the brake fluid from the master cylinder reservoir serving the front disc brakes. Do not drain the reservoir completely.
  2.  
  3. Remove the hub cap and loosen wheel retaining nuts.
  4.  
  5. Raise and support the automobile.
  6.  
  7. Remove the front wheels.
  8.  
  9. Work on one caliper at a time.
  10.  
  11. Wipe all dirt and grease from the caliper brake hose fitting using a shop cloth.
  12.  
  13. Disconnect the brake line at the caliper and discard the hose fitting washer. Cover the open end of the hose with tape or a clean shop cloth.
  14.  
  15. Remove the caliper and brake shoes as outlined in Brake Shoe Replacement.
  16.  
  17. Clean the caliper exterior with brake cleaning solvent.
  18.  
  19. Drain the remaining fluid from the caliper and place the caliper on a clean work surface.
  20.  
  21. Pad the caliper interior with clean shop cloths.
  22.  


CAUTION
Do not, under any circumstances, place your fingers in front of the piston in an attempt to catch or protect it. In addition, use only enough air pressure to ease the piston out of the bore. Excessive air pressure can eject the piston with enough force to cause damage or injury.

  1. Insert the air nozzle into the caliper fluid inlet hole and slowly apply just enough air pressure to ease the piston out of the bore.
  2.  
  3. Remove and discard the dust boot. Use a screwdriver to pry the boot from the bore. Do not scratch the piston bore during boot removal.
  4.  
  5. Remove and discard the piston seal. Use a pencil or similar wood implement to remove the seal.
  6.  


WARNING
Remove the seal using a pencil, wooden stick, piece of plastic, or similar tool only. Do not use a metal tool or similar object to remove the seal, as the bore could be scored.

  1. Remove the bleeder screw.
  2.  
  3. Remove and discard the plastic sleeves and rubber bushings from the caliper mounting ears.
  4.  

Inspect the caliper piston. Replace the piston if nicked, scratched, corroded, or if the protective plating has worn off.


WARNING
Do not attempt to refinish the piston in any way. The outside diameter is the sealing surface and is manufactured to very close tolerances. Removal of the nickle-chrome protective plating will lead to pitting, corrosion, and eventual piston seizure.

Inspect the piston bore. Replace the caliper if the bore is nicked, scratched, worn, cracked, or badly corroded. However, minor stains or corrosion can be removed using crocus cloth.


WARNING
Do not use emery cloth or similar abrasives on the piston bore. If the bore does not clean up with crocus cloth, replace the caliper. Clean the caliper thoroughly with brake fluid or brake cleaning solvent if the bore was polished.

  1. Lubricate the piston bore and replacement seal with brake fluid.
  2.  

To install:

See Figures 2, 3 and 4

Click image to see an enlarged view

Fig. Fig. 2: Lubricate the dust boot with new brake fluid, then install it on the piston



Click image to see an enlarged view

Fig. Fig. 3: Position the dust boot so that its metal retainer is flush with the rim of the caliper piston



Click image to see an enlarged view

Fig. Fig. 4: Use tool J-33028 or its equivalent to seat the dust boot properly in the counterbore

  1. Install the seal in the bore groove. Work the seal into the groove using fingers only.
  2.  
  3. Lubricate the piston with the brake fluid.
  4.  
  5. Install the replacement dust boot on the piston. Slide the metal retainer portion of the seal over the open end of the piston and pull the seal rearward until the rubber boot lip seats in the piston groove.
  6.  
  7. Push the metal retainer portion of the boot forward until the retainer is flush with the rim at the open end of the piston and the seal fold snaps into place.
  8.  
  9. Insert the piston into the bore and into the piston seal. Do not unseat the seal.
  10.  
  11. Press the piston to the bottom of the bore using a hammer handle.
  12.  
  13. Seat the metal retainer portion of the dust boot in the counterbore at the upper end of the piston bore using Tool J-33028 or its equivalent.
  14.  


CAUTION
The metal portion of the dust boot must be seated evenly and below the face of the caliper.

  1. Install the bleeder screw. Tighten the screw securely but not to the required torque until the brakes have been bled.
  2.  
  3. Install the replacement plastic sleeves and rubber bushings in the caliper mounting ears.
  4.  
  5. Check the rotor for face run-out, thickness variation, deep scores, cracks, and broken ventilating ribs.
  6.  
  7. Install the brake shoes and caliper as outlined under Brake Shoe Replacement.
  8.  
  9. Install a replacement washer on the brake hose fitting and connect the hose to the caliper. Tighten the fitting to 25 ft. lbs. torque.
  10.  
  11. Fill the master cylinder to within 1 / 4 in. (6.3mm) of the reservoir rims and bleed the brakes as outlined under Brake Bleeding.
  12.  
  13. After bleeding, press the brake pedal firmly several times to seat the brake shoes. Recheck the master cylinder fluid level and correct it if necessary.
  14.  
  15. Install the wheels and tighten the retaining nuts to 75 ft. lbs. torque.
  16.  
  17. Lower the automobile.
  18.  


CAUTION
Check for a firm brake pedal and proper brake operation before moving the automobile.

 
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