GM: Electra/Park Avenue/Ninety-Eight 1990-1993

Brake Disc (Rotor)

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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! The first step in brake repairs should be cleaning brake surfaces, using a commercially available brake cleaning fluid.

REMOVAL & INSTALLATION



  1. Siphon 2 / 3 of the brake fluid from the master cylinder reservoir. Loosen the wheel lug nuts and raise the car. Remove the wheel.
  2.  
  3. Open the bleeder screws. If they won't turn soak them in penetrating oil and try again later.
  4.  

You want to avoid pushing the piston in with the bleeders closed, especially if the car has anti-lock brakes. Any rust that has formed around the seals with be forced up into the master cylinder or anti-lock brake system. This will cause major abs problems.

  1. Position a C-clamp across the caliper so that it presses on the pads and tighten it until the caliper bottoms in its bore. Large slip joint pliers work well too.
  2.  

If you haven't removed some brake fluid from the master cylinder, it may overflow when the piston is retracted.

  1. Remove the C-clamp.
  2.  
  3. Remove the Allen® head caliper mounting bolts. Inspect the bolts for corrosion and replace as necessary.
  4.  
  5. Remove the caliper from the steering knuckle and suspend it from the body of the car with a length of wire. Do not allow the caliper to hang by its hose.
  6.  
  7. If the original rotor is still on the car star washer retainers will hold the rotor to the hub. Remove and discard these retaining washers.
  8.  
  9. Slide the rotor from the hub. If stuck on, use penetrating oil and tap lightly until free.
  10.  

To install:

  1. Slide new rotor onto hub.
  2.  
  3. Install the caliper onto the steering knuckle. Tighten the mounting bolts to 38 ft. lbs. (51 Nm).
  4.  
  5. Install the wheel and lower the car. Torque lug nuts to 100 ft. lbs. (140 Nm) If the lug nuts aren't torqued, the rotor will warp from heat casing premature wear and noise.
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  7. Fill the master cylinder to its proper level with fresh brake fluid meeting dot 3 specifications. Bleed the brakes, keep checking fluid level as you bleed them.
  8.  

ROTOR INSPECTION



  1. 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. Minimum thickness is stamped on the rotor (or refer to the Brake Specifications chart at the end of this Section). If the rotor will be thinner than this after refinishing, it must be replaced.
  2.  
  3. Check the rotor parallelism; it must vary less than 0.0005 inch (0.0127mm) 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.
  4.  
  5. Measure the disc runout with a dial indicator. If runout exceeds 0.004 inch (0.10mm) for 1985-88 and the wheel bearings are ok (if runout is being measured with the disc on the car), the rotor must be refaced or replaced as necessary.
  6.  

 
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