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

Brake Rotor

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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 brake reservoir using a clean syringe or equivalent.
  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 and suspend it 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.  

If the original rotor is still on the vehicle, it may be retained with star washers, so you must remove and discard these retaining washers.

  1. Remove the rotor assembly by sliding it off the hub. If it is stuck on, use penetrating oil and tap lightly until free.
  2.  

See Figure 1

Click image to see an enlarged view

Fig. Fig. 1: The rotor can be removed by sliding it straight off the hub

To install:
  1. Install the brake rotor over the hub assembly.
  2.  
  3. Install the brake caliper as outlined in this section.
  4.  
  5. Install the wheel and tire assembly.
  6.  
  7. Carefully lower the vehicle. Tighten the wheel lug nuts to 100 ft. lbs. (136 Nm). If the lug nuts aren't tightened properly, the rotor will warp from heat, causing premature wear and noise.
  8.  
  9. Fill the master cylinder reservoir to the FULL level with the correct type of DOT 3 brake fluid from a clean, unsealed container.
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  11. Firmly depress the brake pedal three times to seat the brakes before moving the vehicle.
  12.  

INSPECTION



Check the rotor surface for wear or scoring. Deep scoring, grooves or rust pitting can be removed by refacing, a job to be referred to your local machine shop or garage. All rotors have a minimum thickness dimension cast into them. This dimension is the minimum wear specification, and NOT a refinish dimension. Do not use a rotor, that after refinishing, will not meet the specifications stamped into the rotor.

See Figure 2

Click image to see an enlarged view

Fig. Fig. 2: A rotor with grooves this deep will have to be resurfaced or, more likely, replaced

Check the rotor parallelism; it must vary less than 0.0005 in. (0.013mm) measured at four or more points around the circumference. Make all measurements at the same distance in from the edge of the rotor. Refinish the rotor if it fails to meet this specification.

See Figure 3

Click image to see an enlarged view

Fig. Fig. 3: Checking rotor run-out with a dial indicator

  1. Measure the disc run-out with a dial indicator. If run-out exceeds 0.003 in. (0.080mm), the rotor must be refaced or replaced as necessary.
  2.  

 
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