GM Buick/Oldsmobile/Pontiac/Full-Size 1975-1990 Repair Guide

Brake Calipers

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REMOVAL & INSTALLATION



  1. Perform the removal steps for pad replacement.
  2.  
  3. Disconnect the brake hose and plug the line.
  4.  
  5. Remove the U-shaped retainer from the fitting.
  6.  
  7. Pull the hose from the frame bracket and remove the caliper with the hose attached.
  8.  

To install:
  1. Install the brake hose into the caliper using a new copper gasket.
  2.  
  3. Lubricate the new sleeves and rubber bushings. Install the bushings in the caliper ears. Install the sleeves so that the end toward the disc pad is flush with the machined surface.
  4.  

Lubrication of the sleeves and 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. See Disc Brake Pad Removal and Installation.
  4.  
  5. Reconnect the brake hose to the steel brake line. Install the retainer clip. Bleed the brakes. See Brake Bleeding.
  6.  
  7. Replace the wheels, check the brake fluid level, check the brake pedal travel, and road-test the vehicle.
  8.  

OVERHAUL



See Figures 1, 2, 3, 4 and 5

  1. Clean the outside of the caliper with denatured alcohol.
  2.  
  3. Remove the brake hose and discard the copper gasket.
  4.  
  5. Remove the brake fluid from the caliper.
  6.  
  7. Place clean rags or a piece of wood inside the caliper opening to catch the piston when it is released.
  8.  


CAUTION
Do not place your fingers in front of the piston in an attempt to catch it while applying compressed air; serious injury could result.

  1. Apply compressed air to the caliper fluid inlet hole and force the piston out of its bore. Do not blow the piston out, but use just enough pressure to ease it out.
  2.  
  3. Use a prybar to pry the boot out of the caliper. Avoid scratching the bore.
  4.  
  5. Remove the piston seal from its groove in the caliper bore. Do not use a metal tool of any type for this operation.
  6.  

To install:
  1. Blow out all passages in the caliper and bleeder valve. Clean the piston and piston bore with fresh brake fluid.
  2.  
  3. 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.
  4.  
  5. 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.
  6.  
  7. Lubricate the piston bore and the new rubber parts with fresh brake fluid. Position the seal in the piston bore groove.
  8.  
  9. 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.
  10.  
  11. Insert the piston into the bore, taking care not to unseat the seal.
  12.  
  13. 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.
  14.  



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Fig. Fig. 1: Exploded view of the brake caliper



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Fig. Fig. 2: Use a piece of wood to cushion the piston when blowing it out



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Fig. Fig. 3: Removing the piston from the caliper



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Fig. Fig. 4: Prying the dust boot from the caliper



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Fig. Fig. 5: Removing the square cut seal

 
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