GM Buick/Oldsmobile/Pontiac/Full-Size 1975-1990 Repair Guide

Brake Pads

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CAUTION
Some brake pads 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.

REMOVAL & INSTALLATION



See Figures 1, 2, 3, 4 and 5

  1. Siphon off 2 / 3 of the brake fluid from the master cylinder.
  2.  

The insertion of the thicker replacement pads will push the caliper piston back into its bore and will cause a full master cylinder to overflow.

  1. Raise the vehicle and support it with jackstands. Remove the wheel(s).
  2.  
  3. Install a C-clamp on the caliper so that the solid side of the clamp rests against the back of the caliper and the screw end rests against the metal part of the outboard pad.
  4.  
  5. Tighten the clamp until the caliper moves enough to bottom the piston in its bore. Remove the clamp.
  6.  
  7. Remove the two allen head caliper mounting bolts enough to allow the caliper to be pulled off the disc.
  8.  
  9. Remove the inboard pad and dislodge the outboard pad. Place the caliper where it won't be supported by the brake hose (hang it by a wire hook from the frame).
  10.  
  11. Remove the pad support spring clip from the piston.
  12.  
  13. Remove the two bolt ear sleeves and the four rubber bushings from the ears.
  14.  
  15. Brake pads should be replaced when they are worn to within 1 / 32 in. of the rivet heads.
  16.  

To install:
  1. Check the inside of the caliper for leakage and the condition of the piston dust boot.
  2.  
  3. Lubricate the two new sleeves and four bushings with a silicone spray.
  4.  
  5. Install the bushings in each caliper ear. Install the two sleeves in the two inboard ears.
  6.  
  7. Install the pad support spring clip and the old pad into the center of the piston.
  8.  

On models with wear sensors, make sure the wear sensor is toward the rear of the caliper.

  1. Position the outboard shoe with the ears of the shoes over the caliper ears and the tab at the bottom engaged in the caliper cutout notch.
  2.  
  3. With the two shoes in position, place the caliper over the brake disc and align the holes in the caliper with those of the mounting bracket.
  4.  


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

  1. 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 shoe.
  2.  
  3. Tighten the bolts into the bracket and tighten to 35 ft. lbs. (48 Nm). Bend over the outer pad ears. On 1983 and 1984 vehicles, measure clearance between the caliper and bracket stops. It must be 0.005-0.012 in. (0.127-0.305mm).
  4.  
  5. Install the front wheel and lower the vehicle.
  6.  
  7. Add fluid to the master cylinder reservoirs so that they are 1 / 4 in. (6mm) from the top.
  8.  
  9. Test the brake pedal by pumping it to obtain a hard pedal is obtained. Bleed the brakes if necessary.
  10.  



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Fig. Fig. 1: View of a common front wheel disc brake assembly



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Fig. Fig. 2: Use a C-clamp to seat the piston in it's bore



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Fig. Fig. 3: Removing the caliper mounting bolt



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Fig. Fig. 4: The caliper can be removed by pulling up after the mounting bolts have been removed



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Fig. Fig. 5: Support the caliper with a wire, not by it's hose

INSPECTION



See Figures 6 and 7

Brake pads should be inspected once a year or at 7,500 miles, whichever occurs first. Check both ends of the outboard shoe, looking in at each end of the caliper; then check the lining thickness on the inboard shoe, looking down through the inspection hole. Lining should be more than 0.020 in. (0.5mm) on 1975-82 vehicles; 0.030 in. (0.76mm) on 1983 and later vehicles, thick above the rivet (so that the lining is thicker than the metal backing.). Keep in mind that any applicable state inspection standards that are more stringent take precedence. All four pads must be replaced if one shows excessive wear.

All 1979 and later models have a wear indicator that makes a noise when the linings wear to a degree where replacement is necessary. The spring clip is an integral part of the inboard shoe and lining. When the brake pad reaches a certain degree of wear, the clip will contact the rotor and produce a warning noise.



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Fig. Fig. 6: Disc brake pads with wear indicators



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Fig. Fig. 7: Disc brake pads without wear indicators

 
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