Check the disc brake rotor for scoring, cracks or other damage. Check the minimum thickness and rotor runout.
Either foreign material build-up or contamination on the rotor braking surface or uneven rotor thickness causes a brake pulsation that is present during brake application. If there is a foreign material build-up or contamination found on the rotor or lining surfaces, hand sand the linings and rotors. Uneven rotor thickness (thickness variation) may be caused by excessive runout, caliper drag or the abrasive action of the brake lining. If brake pulsation is present, attempt stopping the vehicle with the transmission in the NEUTRAL position. If the pulsation is gone, the drivetrain should be inspected. If the pulsation remains, inspect the brakes.
Check the rotor thickness using a micrometer or calipers. The brake rotor minimum thickness must not be less than 0.972 in. on 1988-91 vehicles or 0.974 in. on 1992-99 vehicles.
Rotor runout can be checked using a dial indicator. Mount the indicator to the spindle or upper control arm and position the indicator foot on the center of the braking surface. Rotate the rotor to check the runout. On 1992-99 vehicles, make sure there is no rust or foreign material between the rotor and hub face. Hold the rotor to the hub by inverting the lugnuts and tightening them to 85-105 ft. lbs. (115-142 Nm). Rotor runout must not exceed 0.003 in.
If rotor runout exceeds specification on 1988-91 vehicles, machine the rotor if it will not be below the minimum thickness specification after machining. On 1992-00 vehicles, the rotor can be repositioned on the hub to obtain the lowest possible runout. If runout remains excessive, remove the rotor and check the hub runout. Replace the hub if hub runout exceeds 0.002 in. If after replacing the hub, rotor runout remains excessive, machine the rotor if it will not be below the minimum thickness specification after machining.
Removal & Installation
- Raise and safely support the vehicle.
- Remove the wheel and tire assembly.
- Remove the caliper from the spindle and rotor, but do not disconnect the brake hose. Suspend the caliper inside the fender housing with a length of wire. Do not let the caliper hang by the brake hose.
- Remove the rotor retaining push nuts, if equipped, and remove the rotor from the hub.
- Inspect the rotor for scoring and wear. Replace or machine as necessary. If machining, observe the minimum thickness specification.
- If the rotor is being replaced, remove the protective coating from the new rotor with brake cleaner. If the original rotor is being installed, make sure the braking surfaces are clean.
- Install the rotor on the hub.
- Install the caliper and the wheel and tire assembly. Lower the vehicle.
- Apply the brake pedal several times before moving the vehicle, to position the brake pads.