GM Metro/Sprint 1985-1993 Repair Guide

Brake Caliper

Print

REMOVAL & INSTALLATION



See Figure 1

  1. Raise and safely support the front of the vehicle. 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. Mark the relationship between the wheel and the axle hub before removing the tire and wheel assembly.

  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.  

To install:
  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.
  4.  
  5. Install the brake hose to the caliper. Always use a new gasket and tighten the union.
  6.  
  7. Bleed the brake system.
  8.  
  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.  

OVERHAUL



See Figure 1



Click image to see an enlarged view

Fig. Fig. 1: Caliper piston assembly

  1. Remove the brake caliper from the vehicle.
  2.  
  3. Clean the exterior of the brake caliper with brake fluid.
  4.  
  5. Remove the piston boot retaining ring and boot from the caliper by prying off with a flat bladed tool.
  6.  
  7. Remove the piston from caliper using compressed air. Apply air gradually to the brake hose union bolt hole. Cover piston with a shop rag to absorb its momentum.
  8.  


CAUTION
The piston can exit the caliper with explosive force. Apply compressed air gradually and keep fingers out of the way.

  1. Remove the piston seal from caliper using a thin bladed tool.
  2.  
  3. Remove the bleeder valve and cap from the caliper.
  4.  
  5. Clean all parts in denatured alcohol.
  6.  
  7. Dry all parts and blow out all passages in caliper housing and bleeder valve with compressed air.
  8.  
  9. Inspect the piston for scoring, nicks, corrosion or wear. Replace as necessary.
  10.  
  11. Inspect caliper bore and seal for scoring, nicks, corrosion and wear. Replace components as necessary.
  12.  
  13. Inspect caliper upper and lower slide bushings and boots for wear and corrosion.
  14.  
  15. Install piston seal and boot with clean brake fluid.
  16.  
  17. Install bleeder valve and cap. Tighten bleeder valve to 89 inch lbs. (10 Nm).
  18.  
  19. Install new piston seal into groove on caliper housing. Make sure the seal is not twisted.
  20.  
  21. Install new boot to piston. Install with the double grooved side toward the piston and the triple grooved side outward.
  22.  
  23. Install the piston and boot to caliper. Seat piston boot onto caliper. Position piston so it protrudes from the caliper 0.40 in. (10mm).
  24.  
  25. Install piston boot retaining ring.
  26.  
  27. Install caliper on vehicle.
  28.  

 
label.common.footer.alt.autozoneLogo