GM Full Size Vans 1987-1997 Repair Guide

Brake Caliper

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REMOVAL & INSTALLATION



Delco System
  1. Remove the cover on the master cylinder and siphon enough fluid out of the reservoirs to bring the level to 1 / 3 full. This step prevents spilling fluid when the piston is pushed back.
  2.  
  3. Raise and support the vehicle. Remove the front wheels and tires.
  4.  
  5. Push the brake piston back into its bore using a C-clamp to pull the caliper outward.
  6.  
  7. Remove the two bolts which hold the caliper and then lift the caliper off the disc.
  8.  


WARNING
Do not let the caliper assembly hang by the brake hose.

  1. Remove the inboard and outboard shoe.
  2.  

If the pads are to be reinstalled, mark them inside and outside.

  1. Remove the pad support spring from the piston.
  2.  
  3. Remove the two sleeves from the inside ears of the caliper and the 4 rubber bushings from the grooves in the caliper ears.
  4.  
  5. Remove the hose from the steel brake line and tape the fittings to prevent foreign material from entering the line or the hoses.
  6.  
  7. Remove the retainer from the hose fitting.
  8.  
  9. Remove the hose from the frame bracket and pull off the caliper with the hose attached.
  10.  
  11. Check the inside of the caliper for fluid leakage; if so, the caliper should be overhauled.
  12.  


WARNING
Do not use compressed air to clean the inside of the caliper, as this may unseat the dust boot.

To install:
  1. Connect the brake line to start re-installation. Lubricate the sleeves, rubber bushings, bushing grooves, and the end of the mounting bolts using silicone lubricant.
  2.  
  3. Install new bushing in the caliper ears along with new sleeves. The sleeve should be replaced so that the end toward the shoe is flush with the machined surface of the ear.
  4.  
  5. Position the support spring and the inner pad into the center cavity of the piston, snap the retaining spring into the piston. The outboard pad has ears which are bent over to keep the pad in position while the inboard pad has ears on the top end which fit over the caliper retaining bolts. A spring which is inside the brake piston hold the bottom edge of the inboard pad.
  6.  
  7. Push down on the inner pad until it lays flat against the caliper. It is important to push the piston all the way into the caliper if new linings are installed or the caliper will not fit over the rotor.
  8.  
  9. Position the outboard pad with the ears of the pad over the caliper ears and the tab at the bottom engaged in the caliper cutout.
  10.  
  11. With the two pads in position, place the caliper over the brake disc and align the holes in the caliper with those of the mounting bracket.
  12.  


WARNING
Make certain that the brake hose is not twisted or kinked.

  1. Fill the cavity between the bolt bushings with silicone grease. Install the mounting bracket bolts through the sleeves in the inboard caliper ears and through the mounting bracket, making sure that the ends of the bolts pass under the retaining ears on the inboard pad.
  2.  

For best results, always use new bushings, sleeves and bolt boots.

  1. Tighten the mounting bolts to 38 ft. lbs. (51 Nm). Pump the brake pedal to seat the pad against the rotor. Don't do this unless both calipers are in place. Use a pair of channel lock pliers to bend over the upper ears of the outer pad so it isn't loose.
  2.  

After tightening the mounting bolts, there must be clearance between the caliper and knuckle at both the upper and lower edge. The clearance must be 0.010-0.024 in. (0.26-0.60mm). If not, loosen the bolts and reposition the caliper.

  1. Install the front wheel and lower the vans.
  2.  
  3. Add fluid to the master cylinder reservoirs so that they are 1 / 4 in. (6mm) from the top.
  4.  
  5. Test the brake pedal by pumping it to obtain a hard pedal. Check the fluid level again and add fluid as necessary. Do not move the vehicle until a hard pedal is obtained.
  6.  

Bendix System
  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 32 ft. lbs. (43 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



See Figures 1 through 13

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


WARNING
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 Delco caliper - 1987-95 models



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Fig. Fig. 2: Force the piston out with compressed air - Delco



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



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Fig. Fig. 4: Prying out the piston boot - Delco



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Fig. Fig. 5: Remove the piston seal from the caliper



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Fig. Fig. 6: Exploded view of the Delco caliper used on models with a GVW rating of 6100 through 9500 lbs.



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Fig. Fig. 7: Exploded view of the Delco caliper used on models with a minimum GVW rating of 10,000 lbs.

  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.  



Click image to see an enlarged view

Fig. Fig. 8: Installing the boot on the piston - Delco



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Fig. Fig. 9: Installing the piston - Delco



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Fig. Fig. 10: Exploded view of the caliper - Bendix



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Fig. Fig. 11: Force the piston out with compressed air - Bendix



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Fig. Fig. 12: Removing the piston boot - Bendix



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Fig. Fig. 13: Installing the piston - Bendix

 
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