GM Astro/Safari 1985-1996 Repair Guide

Brake Pads

Print


CAUTION
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.

INSPECTION



See Figures 1, 2, 3 and 4



Click image to see an enlarged view

Fig. Fig. 1: The brake pad wear warning sensor will squeal once the pad is thin enough that the tab touches the rotor



Click image to see an enlarged view

Fig. Fig. 2: Brake pad inspection points



Click image to see an enlarged view

Fig. Fig. 3: Get to know what a worn pad looks like versus a new pad



Click image to see an enlarged view

Fig. Fig. 4: Measure the thickness of the friction material, not the backing plate

Brake pads should be inspected once a year or at 7500 miles (12,000 km), which ever 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. The lining should be more than 1 / 32 in. (0.8mm) 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 4 pads must be replaced if one shows excessive wear.

All 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.

REMOVAL & INSTALLATION



See Figures 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 and 18



Click image to see an enlarged view

Fig. Fig. 5: The standard GM front disc brake



Click image to see an enlarged view

Fig. Fig. 6: Exploded view of the caliper and pad components-Two wheel drive



Click image to see an enlarged view

Fig. Fig. 7: Exploded view of the caliper and pad components-All wheel drive



Click image to see an enlarged view

Fig. Fig. 8: A prybar can be used to press the pads into the caliper enough to remove the caliper ...



Click image to see an enlarged view

Fig. Fig. 9: ... or a C-clamp applied to the outboard pad will press the piston in the bore without cocking



Click image to see an enlarged view

Fig. Fig. 10: Use the proper socket on the caliper bolts. There have been different types of bolt heads used



Click image to see an enlarged view

Fig. Fig. 11: The pins are the only thing that hold the caliper to the mount



Click image to see an enlarged view

Fig. Fig. 12: Check the pins for corrosion and damage



Click image to see an enlarged view

Fig. Fig. 13: Pull the caliper straight off the rotor to remove otherwise it could bind



Click image to see an enlarged view

Fig. Fig. 14: Support the caliper so the weight does not pull on the brake line



Click image to see an enlarged view

Fig. Fig. 15: Separate the outer pad from the caliper. You may need a small prybar to do this if the fit is tight



Click image to see an enlarged view

Fig. Fig. 16: The inner pad is held by this spring. Make sure it is in place before installing the new pad



Click image to see an enlarged view

Fig. Fig. 17: Upon installation, the pad will click into place if the retainer spring is installed properly



Click image to see an enlarged view

Fig. Fig. 18: An often forgotten step is compressing the brake pad ears. If it isn't done, the pads can rattle

The following procedure requires the use of a C-clamp and slip-joint lock pliers.

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


CAUTION
The insertion of thicker replacement pads will push the piston back into its bore and will cause a full master cylinder reservoir to overflow, possibly causing paint damage. In addition to siphoning off fluid, it would be wise to keep the reservoir cover on during pad replacement.

  1. Raise and support the front of the vehicle on jackstands. Remove the wheels.
  2.  

When replacing the pads on just one wheel, uneven braking will result; always replace the pads on both wheels.

  1. Install a C-clamp on the caliper so that the frame side of the clamp rests against the back of the caliper and so the screw end rests against the metal part (shoe) of the outboard pad.
  2.  
  3. Tighten the clamp until the caliper moves enough to bottom the piston in its bore. Remove the clamp.
  4.  
  5. Remove the 2 Allen head caliper mounting bolts enough to allow the caliper to be pulled off the disc.
  6.  
  7. Remove the inboard pad and loosen the outboard pad. Place the caliper where it will not strain the brake hose; it would be best to wire it out of the way.
  8.  
  9. Remove the pad support spring clip from the piston.
  10.  
  11. Remove the 2 bolt ear sleeves and the 4 rubber bushings from the ears.
  12.  
  13. Riveted style brake pads should be replaced when they are worn to within 1 / 32 in. (0.8mm) of the rivet heads; bonded style pads should be replaced when they are worn to no less than 1 / 32 in. (0.8mm) of the backing plate.
  14.  
  15. Check the inside of the caliper for leakage and the condition of the piston dust boot.
  16.  

To install:
  1. Lubricate the 2 new sleeves and 4 bushings with a silicone spray.
  2.  
  3. Install the bushings in each caliper ear. Install the 2 sleeves in the 2 inboard ears.
  4.  
  5. Install the pad support spring clip and the old pad into the center of the piston. You will then push this pad down to get the piston flat against the caliper. This part of the job is a hassle and requires an assistant. While the assistant holds the caliper and loosens the bleeder valve to relieve the pressure, obtain a medium pry bar and try to force the old pad inward, making the piston flush with the caliper surface. When it is flush, close the bleeder valve so that no air gets into the system.
  6.  

Make sure that the wear sensor is facing toward the rear of the caliper.

  1. Place the outboard pad in the caliper with its top ears over the caliper ears and the bottom tab engaged in the caliper cutout.
  2.  
  3. After both pads are installed, lift the caliper and place the bottom edge of the outboard pad on the outer edge of the disc to make sure that there is no clearance between the tab on the bottom of the shoes and the caliper abutment.
  4.  
  5. Place the caliper over the disc, lining up the hole in the caliper ears with the hole in the mounting bracket. Make sure that the brake hose is not kinked.
  6.  
  7. Start the caliper-to-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 of the inboard shoe.
  8.  
  9. Push the mounting bolts through to engage the holes in the outboard shoes and the outboard caliper ears and then threading them into the mounting bracket.
  10.  
  11. Torque the mounting bolts to 37 ft. lbs. (50 Nm). Pump the brake pedal to seat the linings against the rotors.
  12.  
  13. Using a pair of slip-joint locking pliers, place them on the notch on the caliper housing, bend the caliper upper ears until no clearance exists between the shoe and the caliper housing.
  14.  
  15. Install the wheels, lower the vehicle and refill the master cylinder reservoirs with brake fluid. Pump the brake pedal to make sure that it is firm. If it is not, bleed the brakes.
  16.  

 
label.common.footer.alt.autozoneLogo