GM Service Manual Online
For 1990-2009 cars only

Tolerances of the braking surfaces for the following conditions are held closely during the manufacture of the brake rotor:

    • Flatness
    • Parallelism
    • Lateral runout

The maintenance of close tolerances on the shape of the braking surfaces is necessary in order to prevent brake roughness or pulsation. The surface finish must be held to a specified range of a 60 degree radius of roughness or less. A new rotor conforms to the above specifications, as will a correctly refinished rotor. For front and rear brake rotors, refer to Brake Rotor Refinishing .. Control of the braking surface finish will eliminate the following problems:

    • Hard pedal application
    • Excessive brake fade
    • Pulls
    • Erratic performance.
        Control of the braking surface finish will improve lining life.

Light scoring of the rotor surfaces not exceeding 1.5 mm (0.060 in) in depth is not detrimental to brake operation. Normal use may cause light scoring.