GM Full Size Vans 1987-1997 Repair Guide

Brake Caliper

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REMOVAL & INSTALLATION




CAUTION
Brake shoes may contain asbestos, which has been determined to be a cancer causing agent. Never clean the brake surfaces with compressed air! Avoid inhaling any dust from any brake surface! When cleaning brake surfaces, use a commercially available brake cleaning fluid.

See Figures 1 through 4

  1. Remove approximately 1 / 3 of the brake fluid from the master cylinder. Discard the used brake fluid.
  2.  
  3. Raise and support the front end on jackstands.
  4.  
  5. Push the piston back into its bore. This can be done by suing a C-clamp.
  6.  
  7. Remove the bolt at the caliper support key. Use a brass drift pin to remove the key and spring.
  8.  
  9. Rotate the caliper up and forward from the bottom and lift it off the caliper support.
  10.  
  11. Unscrew the brake line at the caliper. Plug the opening. Discard the copper washer. Be careful not to damage the brake line.
  12.  
  13. Remove the outer shoe from the caliper.
  14.  

To install:
  1. Using a new copper washer, connect the brake line at the caliper. Tighten the connector to 33 ft. lbs. (45 Nm)
  2.  
  3. Lubricate the caliper support and support spring with silicone.
  4.  
  5. Position the outboard shoe in the caliper with the ears at the top of the shoe over the caliper ears and the tab at the bottom of the shoe engaged in the caliper cutout. If assembly is difficult, a C-clamp may be used. Be careful not to mar the lining.
  6.  
  7. Position the caliper over the brake disc, top edge first. Rotate the caliper downward onto the support.
  8.  
  9. Place the spring over the caliper support key, install the assembly between the support and lower caliper groove. Tap into place until the key retaining screw can be installed.
  10.  
  11. Install the screw and tighten to 15 ft. lbs. (20 Nm). The boss must fit fully into the circular cutout in the key.
  12.  
  13. Install the wheel and add brake fluid as necessary.
  14.  

OVERHAUL



The following procedure applies to both the Delco and Bendix types of calipers.


CAUTION
Use only denatured alcohol to clean metal parts and brake fluid to clean rubber parts. Never use any mineral based cleaning solvents such as gasoline or kerosene as these solvents will deteriorate rubber parts.

  1. Remove the caliper, clean it and place it on a clean and level work surface.
  2.  



Click image to see an enlarged view

Fig. Fig. 1: Exploded view of the caliper



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Fig. Fig. 2: Remove the piston with compressed air



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Fig. Fig. 3: Pry out the piston boot



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Fig. Fig. 4: Installing the piston

  1. Remove the brake hose from the caliper and discard the copper gasket. Check the brake hose for cracks or deterioration. Replace the hose as necessary.
  2.  
  3. Drain the brake fluid from the caliper.
  4.  
  5. Pad the interior of the caliper with cloth and then apply compressed air to the caliper inlet hose.
  6.  


CAUTION
Do not place your hands or fingers in front of the piston in an attempt to catch it! Use just enough air pressure to ease the piston out of the bore.

  1. Remove the piston dust boot by prying it out with a screwdriver. Use caution when performing this procedure.
  2.  
  3. Remove the piston seal from the caliper piston bore using a small piece of wood or plastic. DO NOT use any type of metal tool for this procedure.
  4.  
  5. Remove the bleeder valve from the caliper.
  6.  

Dust boot, piston seal, rubber bushings, and sleeves are included in every rebuilding kit. These should be replaced at every caliper rebuild.

  1. Clean all parts in the recommended solvent and dry them completely using compressed air if possible.
  2.  

The use of shop air hoses may inject oil film into the assembly; use caution when using such hoses.

  1. Examine the mounting bolts for rust or corrosion. Replace them as necessary.
  2.  
  3. Examine the piston for scoring, nicks, or worn plating. If any of these conditions are present, replace them as necessary.
  4.  


WARNING
Do not use any type of abrasive on the piston!

  1. Check the piston bore. Small defects can be removed with crocus cloth. If the bore cannot be cleaned in this manner, replace the caliper.
  2.  
  3. Lubricate the piston bore and the new piston seal with brake fluid. Place the seal in the caliper bore groove.
  4.  
  5. Lubricate the piston in the same manner and position the new boot into the groove in the piston so that the fold faces the open end of the piston.
  6.  
  7. Place the piston into the caliper bore using caution not to unseat the seal. Force the piston to the bottom of the bore.
  8.  
  9. Place the dust boot in the caliper counterbore and seat the boot. Make sure that the boot in positioned correctly and evenly.
  10.  
  11. Install the brake hose in the caliper inlet using a new copper gasket.
  12.  

The hose must be positioned in the caliper locating gate to assure proper positioning of the caliper.

  1. Replace the bleeder screw.
  2.  
  3. Bleed the system.
  4.  

 
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