GM Corvette 1984-1996 Repair Guide

Brake Disc (Rotor)



Older brake pads or shoes may contain asbestos, which has been determined to be 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.

See Figures 1 and 2

  1. Disconnect battery negative cable.
  3. Unbolt the caliper assembly, but do not disconnect the fluid line. Suspend the caliper assembly using a length of mechanic's wire. For more details, refer to the appropriate caliper removal procedure for you vehicle, located earlier in this section.

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Fig. Fig. 1: Remove the rotor by lifting it straight off the lug studs-rear rotor shown

  1. Remove the rotor from the vehicle by pulling it straight off the lug studs.
  3. Installation is the reverse of removal.

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Fig. Fig. 2: Install the rotor by positioning it over the lug studs, and pushing it into place-front rotor shown


See Figure 3

  1. Check the rotor surface for wear, scoring, grooves or rust pitting. Rotor damage can be corrected by refacing, consult your local garage or machine shop. Light scoring of the rotor surface which does not exceed 0.060 in. (1.5mm) is generally not detrimental to brake operation and may be caused by normal use. If the damage exceeds the minimum thickness, which is stamped on the rotor, replace the rotor.

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Fig. Fig. 3: The rotor should a "Minimum Thickness" specification stamped into it

Thickness Variation Check

Check rotor thickness variation by measuring the rotor thickness at 4 or more points around the circumference of the rotor. Use a micrometer calibrated in ten-thousandths of an inch. Make all of your measurements at the same distance in from the edge of the rotor. A rotor that varies in thickness by more that 0.0005 in. (0.013mm) may cause your brake pedal to pulsate and/or front end vibration when the brakes are applied. A rotor not meeting these specifications must be refinished or replaced.

Lateral Runout Check

The best way to check lateral runout is with the wheels still installed on the vehicle. This ensures a much more accurate reading. If the proper equipment is not available to do this, the next best reading can be made with the wheels removed, but the caliper installed, as follows:

  1. If the wheels are removed, re-install the lug nuts to hold the rotor in place. Tighten the lug nuts to 100 ft. lbs. (136 Nm).
  3. Attach a dial indicator to the steering knuckle so that the indicator button contacts the rotor surface about 1 / 2 in. from the outer edge.
  5. Set the dial indicator to zero.
  7. Turn the wheel one complete revolution and check the runout indicated on the dial. The total indicated runout must not exceed 0.003 in. (0.08mm).

Sometimes, excessive lateral runout can be improved by indexing the rotor on the hub one or two bolt positions from the original position. If this doesnt work, check the hub and bearing for excessive lateral runout or looseness. If those specifications exceed 0.0015 in. (0.040mm), replace the hub and bearing. If the lateral runout is within specifications, refinish or replace the rotor, as necessary.

Whenever the rotor is separated from the wheel bearing flange, thoroughly clean the any rust or other debris from the wheel bearing flange and rotor mating surfaces. If you don't do this, the lateral runout and brake pulsation may be increased.

  1. If the lateral runout exceeds the specification in Step 4, refinish or replace the rotor.