GM Prizm/Nova 1985-1993 Repair Guide

Brake Caliper

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REMOVAL




CAUTION
Brake pads and shoes 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 brake surfaces! When cleaning brakes, use commercially available brake cleaning fluids.

  1. Raise and safely support the front of the vehicle on jackstands. Set the parking brake and block the rear wheels.
  2.  
  3. Siphon a sufficient quantity of brake fluid from the master cylinder reservoir to prevent the brake fluid from overflowing the master cylinder when removing or installing the calipers. This is necessary as the piston must be forced into the cylinder bore to provide sufficient clearance to install the caliper.
  4.  
  5. Remove the wheel, then reinstall 2 lug nuts finger tight to hold the disc in place.
  6.  

Disassemble brakes one wheel at a time. This will prevent parts confusion and also prevent the opposite caliper piston from popping out during installation.

  1. Disconnect the hose union at the caliper. Use a pan to catch any spilled fluid and immediately plug the disconnected hose.
  2.  
  3. Remove the 2 caliper mounting bolts and then remove the caliper from the mounting bracket.
  4.  

OVERHAUL



See Figures 1 and 2

  1. Drain the remaining fluid from the caliper.
  2.  
  3. Carefully remove the dust boot from around the piston.
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  5. Pad the inside arms of the caliper with rags. Apply compressed air into the brake line port; this will force the piston out.
  6.  


CAUTION
Do not place fingers in front of the piston in an attempt to catch it or protect it when applying compressed air. Injury can result. Use just enough air pressure to ease the piston out of the bore.



Click image to see an enlarged view

Fig. Fig. 1: Use just enough air to ease the piston out of the caliper. Keep fingers out of the way of the piston

  1. Remove the seal from the inside of the caliper bore. Check all the parts for wear, scoring, deterioration, cracking or other abnormal conditions. Corrosion - generally caused by water in the system - will appear as white deposits on the metal, similar to what may be found on an old aluminum storm door on your house. Pay close attention to the condition of the inside of the caliper bore and the outside of the piston. Any sign of corrosion or scoring requires new parts; do not attempt to clean or resurface either face.
  2.  
  3. The caliper overhaul kit will, at minimum, contain new seals and dust boots. A good kit will contain a new piston as well, but you may have to buy the piston separately. Any time the caliper is disassembled, a new piston is highly recommended in addition to the new seals.
  4.  
  5. Clean all the components to be reused with an aerosol brake solvent and dry them thoroughly. Take any steps necessary to eliminate moisture or water vapor from the parts.
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  7. Coat all the caliper components with fresh brake fluid from a new can.
  8.  

Some repair kits come with special assembly lubricant for the piston and seal. Use this lubricant according to directions with the kit.

  1. Install the piston seal and piston into the caliper bore. This is an exacting job; the clearances are very small. Make sure that the seal is seated in its groove and that the piston is not cocked when inserted into the bore.
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  3. Install the dust boot and its clip or ring.
  4.  
  5. Install the slide bushings and rubber boots onto the caliper if they were removed during disassembly.
  6.  

INSTALLATION





Click image to see an enlarged view

Fig. Fig. 2: Using a large C-clamp to compress the piston back into the caliper bore

  1. Use a caliper compressor, a C-clamp or large pair of pliers to slowly press the caliper piston back into the caliper.
  2.  
  3. Install the caliper assembly to the mounting plate. Before installing the retaining bolts, apply a thin, even coating of anti-seize compound to the threads and slide surfaces. Don't use grease or spray lubricants; they will not hold up under the extreme temperatures generated by the brakes. Tighten the bolts to 18 ft. lbs. (25 Nm) for 1985-92 and 25 ft. lbs. (34 Nm) for 1993.
  4.  
  5. Install the brake hose to the caliper. Always use a new gasket and tighten the union to 17 ft. lbs.
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  7. Bleed the brake system.
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  9. Remove the 2 lugs holding the disc in place and install the wheel.
  10.  
  11. Lower the vehicle to the ground. Check the level of the brake fluid in the master cylinder reservoir; it should be at least to the middle of the reservoir.
  12.  

 
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