GM Lumina/Silhouette/Transport APVs 1990-1999 Repair Guide

Brake Pads

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Always replace all pads on both front wheels at the same time. Failure to do so will result in uneven braking action and premature wear.

REMOVAL AND INSTALLATION




CAUTION
Older brake pads or shoes may 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 the brake surfaces, use a commercially available brake cleaning fluid.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove 2 / 3 of the brake fluid from the master cylinder reservoir using a clean syringe or equivalent. Install the reservoir cap.
  4.  
  5. Raise and safely support the vehicle with jackstands.
  6.  
  7. Mark the relationship of the wheel to the hub and bearing assembly.
  8.  
  9. Remove the tire and wheel assembly.
  10.  
  11. Remove the caliper, as outlined later, and suspend from the strut with a wire hook or suitable piece of wire. Do NOT disconnect the brake hose or allow the caliper to hang from the brake line!
  12.  

See Figures 1, 2 and 3

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Fig. Fig. 1: Properly suspending the caliper, using a wire hook

  1. Remove the outboard shoe and lining (pad) by using a prytool to disengage the buttons on the shoe from the holes in the caliper housing.
  2.  



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Fig. Fig. 2: Use a prytool to release the outboard pad retaining buttons



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Fig. Fig. 3: Remove the outboard brake pad from the caliper

  1. Remove the inboard shoe and lining (pad) from the caliper.
  2.  

See Figures 4 and 5

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Fig. Fig. 4: Slide the inboard pad outward, disengaging the retaining clip ears...



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Fig. Fig. 5: and remove the inboard pad from the caliper.

  1. Before installing new pads, clean the outside surface of the caliper boot with denatured alcohol, or equivalent.
  2.  

To install:
  1. Lubricate the sleeves and bushings with silicone lubricant and install them in the caliper.
  2.  
  3. One method of pushing the piston back into the bore is to use a large pair of adjustable pliers over the caliper housing and bottom the piston into the caliper bore. Another is to use the special disc brake tool available at most part stores, or even a large C-clamp will work.
  4.  

See Figures 6, 7 and 8

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Fig. Fig. 6: You can use a large pair of channel type slip joint pliers to compress the caliper piston into its bore



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Fig. Fig. 7: There is a special tool available to compress the caliper piston into its bore ...



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Fig. Fig. 8: ...or you can use a large C-clamp to compress the piston into the bore

Be careful not to damage the piston or piston boot with the pliers.

  1. After bottoming the piston into the caliper bore, fit the inner edge of the boot next to the piston and press out any trapped air. The boot must lay flat.
  2.  
  3. Clip the retaining spring onto the back of the inboard pad and install the pad in the caliper. The shoe must lie flat against the caliper.
  4.  

See Figure 9

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Fig. Fig. 9: Install the inboard pad, making sure the retainer spring is fastened securely in the caliper piston

  1. Install the outboard pad into the caliper with the wear sensor at the leading edge of the shoe during forward wheel rotation. The back of the shoe must lie flat against the caliper.
  2.  

See Figure 10

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Fig. Fig. 10: The outboard brake pad must be installed with the wear sensor at the trailing edge of the pad

  1. Install the caliper, as outlined later in this section.
  2.  
  3. Install the wheel and tire assembly, then carefully lower the vehicle. Tighten the wheel lug nuts to 100 ft. lbs. (136 Nm).
  4.  
  5. Fill the master cylinder with the proper amount of brake fluid from a fresh, sealed container. Install the reservoir cap.
  6.  
  7. Apply about 175 lbs. (778 N) of force to the brake pedal, three times, to seat the pads.
  8.  

INSPECTION



The pad thickness should be inspected every time that the tires are removed for rotation. The outer pad has a wear sensor which will make a squealing noise when the pads wear to the point required replacement.

See Figure 11

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Fig. Fig. 11: The outboard pad has a wear sensor that will make a screeching noise against the rotor when the pad is worn to a certain limit

When the pad thickness is worn to within 1 / 32 in. (0.76mm) of the shoe or rivet, at either end of the pad, replace the pads in axle sets. This is the factory recommended measurement; however, your state's automobile inspection laws may not agree with this.

When checking the disc brakes, check both ends of the outer pads by looking in at each end of the caliper. These are the points at which the highest rate of wear occurs. The inner pad can be checked for premature wear by looking down through the inspection hole in the top of the caliper. Some inboard pads have a thermal layer against the shoe, integrally molded with the lining. Do not confuse this extra layer with uneven inboard/outboard pad wear.

See Figure 12

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Fig. Fig. 12: Disc brake pad inspection points

 
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