For 1990-2009 cars

Warning: Refer to Brake Dust Warning in the Preface section.

1. If the inboard friction surface of the brake rotor is not accessible, reposition and support the caliper with the brake pads. Refer to Front Disc Brake Pads Replacement and/or Rear Disc Brake Pads Replacement.
2. Clean the friction surfaces of the brake rotor with denatured alcohol, or an equivalent approved brake cleaner.
3. Using a micrometer calibrated in thousanths-of-a-millimeter, or ten-thousanths-of-an-inch, measure and record the thickness of the brake rotor at four or more points, evenly spaced around the rotor.

Ensure that the measurements are only taken within the friction surfaces and that the micrometer is positioned the same distance from the outer edge of the rotor, about 13 mm (½ in), for each measurement.

4. Compare the lowest thickness measurement recorded to the following specifications.

Specification

• | Front brake rotor minimum allowable thickness after refinishing: 30.7 mm (1.209 in).

• | Front brake rotor (J56) minimum allowable thickness after refinishing: 31.0 mm (1.220 in).

• | Rear brake rotor minimum allowable thickness after refinishing: 24.0 mm (0.944 in).

• | Front brake rotor discard thickness: 30.7 mm (1.209 in).

• | Front brake rotor (J56) discard thickness: 30.00 mm (1.181 in).

• | Rear brake rotor discard thickness 24.0 mm (0.944 in).

• | Rear brake rotor (J56) minimum allowable thickness after refinishing: 27.0 mm (1.062 in).

• | Rear brake rotor (J56) discard thickness: 26.00 mm (1.023 in).

5. If the lowest thickness measurement of the brake rotor is above the minimum allowable thickness specification, you may be able to resurface the brake rotor, depending upon the surface and wear conditions which may be present.
6. If the lowest thickness measurement of the brake rotor is equal to or below the minimum thickness after refinishing specification, the rotor may not be refinished.
7. If the lowest thickness measurement of the brake rotor is equal to or below the discard thickness specification, the rotor requires replacement.