Initial Inspection and Diagnostic Overview
Diagnostic Starting Point - Disc BrakesBegin the disc brake system diagnosis with Diagnostic Starting Point - Hydraulic Brakes in Hydraulic Brakes. The use of the Diagnostic Starting Point will lead to the identification of the correct procedure for diagnosing the system and where the procedure is located.
Brake Rotor Thickness Measurement
Caution: Refer to Brake Dust Caution in Service Precautions.
1. If the inboard friction surface of the brake rotor is not accessible, reposition and support the caliper with the brake pads.
2. Clean the friction surfaces of the brake rotor with denatured alcohol, or an equivalent approved brake cleaner.
3. Using a micrometer calibrated in thousandths-of-a-millimeter, or ten-thousandths-of-an-inch, measure and record the lowest thickness of the brake rotor at 4 or more points, equally 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 outside edge of the rotor, about 13 mm (1/2 inch), for each measurement.
4. Compare the lowest thickness measurement recorded to the following specifications:
^ Brake rotor minimum allowable thickness after refinishing: 23 mm (0.906 inch)
^ Brake rotor discard thickness: 22.8 mm (0.898 inch)
5. Specification - Rear
^ Brake rotor minimum allowable thickness after refinishing: 12.0 mm (0.472 inch)
^ Brake rotor discard thickness: 11.8 mm (0.465 inch)
6. If the lowest thickness measurement of the brake rotor is above the minimum allowable thickness after refinishing specification, the rotor may be able to be refinished, depending upon surface and wear conditions which may be present.
7. If the lowest thickness measurement of the brake rotor is at or below the minimum allowable thickness after refinishing specification, the rotor may not be refinished.
8. If the lowest thickness measurement of the brake rotor is at or below the discard thickness specification, the rotor requires replacement.