GM Metro/Sprint 1985-1993 Repair Guide

Disc Brake Pads

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REMOVAL & INSTALLATION



See Figures 1 through 10



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Fig. Fig. 1: Front disc brake assembly



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Fig. Fig. 2: Removing caliper mounting bolts



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



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Fig. Fig. 4: Removing the outside brake pad



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Fig. Fig. 5: Removing the inside brake pad



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Fig. Fig. 6: The inside brake pad is attached to the caliper piston with a spring clip


CAUTION
Brake 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 any brake surface! When cleaning brake surfaces, us a commercially available brake cleaning fluid!

  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 from the master cylinder when removing or installing the brake pads. This is necessary as the piston must be forced into the cylinder bore to provide sufficient clearance to install the pads.
  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 pad installation.

  1. Remove the 2 caliper mounting bolts and then remove the caliper from the mounting bracket. Position the caliper out of the way and support it with wire so it doesn't hang by the brake line.
  2.  

It may be necessary to rock the caliper back and forth a bit in order to reposition the piston so it will clear the brake pads.

  1. Remove the brake pads, the wear indicators, the anti-squeal shims, the support plates and the anti squeal springs (if so equipped). Disassemble slowly and take note of how the parts fit together. This will save much time during reassembly.
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  3. Inspect the brake disc (both sides) for scoring or gouging. Measure the disc for both thickness and run-out. Complete inspection procedures are given later in this section.
  4.  
  5. Inspect the pads for remaining thickness and condition. Any sign of uneven wear, cracking, heat checking or spotting is cause for replacement. Compare the wear of the inner pad to the outer pad. While they will not wear at exactly the same rate, the remaining thickness should be about the same on both pads. If one is heavily worn and the other is not, suspect either a binding caliper piston or dirty slides in the caliper mount.
  6.  
  7. Examine the 2 caliper retaining bolts and the slide bushings in which they run. Everything should be clean and dry. If cleaning is needed, use spray solvents and a clean cloth. Do not wire brush or sand the bolts-this will cause grooves in the metal which will trap more dirt. Check the condition of the rubber dust boots and replace them if damaged.
  8.  



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Fig. Fig. 7: Disc brake system hardware. Inside pad is at top and outside pad is on bottom. Note wear indicator springs protruding from sides of outside pad



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Fig. Fig. 8: Removing the anti-squeal springs from the caliper wear indicators



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Fig. Fig. 9: Using a C-clamp to compress the caliper piston



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Fig. Fig. 10: Coat the caliper mounting bolts with anti-seize during installation

To install:
  1. Install the pad support plates onto the mounting bracket.
  2.  
  3. Install new pad wear indicators onto each pad, making sure the arrow on the tab points in the direction of disc rotation.
  4.  
  5. Install new anti-squeal pads to the back of the pads.
  6.  
  7. Install the pads into the mounting bracket and install the anti-squeal springs.
  8.  
  9. Use a caliper compressor, or a C-clamp to slowly press the caliper piston back into the caliper. If the piston is frozen, or if the caliper is leaking hydraulic fluid, the caliper must be overhauled or replaced.
  10.  
  11. 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 specification.
  12.  
  13. Remove the 2 lugs holding the disc in place and install the wheel.
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  15. 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.
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  17. Depress the brake pedal several times and make sure that the movement feels normal. The first brake pedal application may result in a very "long" pedal due to the pistons being retracted. Always make several brake applications before starting the vehicle. Bleeding is not usually necessary after pad replacement.
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  19. Recheck the fluid level and add to the "MAX" line if necessary.
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Braking should be moderate for the first 5 miles or so until the new pads seat correctly. The new pads will bed best if put through several moderate heating and cooling cycles. Avoid hard braking until the brakes have experienced several long, slow stops with time to cool in between. Taking the time to properly bed the brakes will yield quieter operation, more efficient stopping and contribute to extended brake life.

 
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