Brake Rotor Surface and Wear Inspection JL9, J55, J56

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. Inspect the friction surfaces of the brake rotor for the following Braking Surface Conditions:

•	Heavy rust and/or pitting

Light surface rust can be removed with an abrasive disc. Heavy surface rust and/or pitting must be removed by refinishing the rotor.

•	Cracks and/or heat spots

•	Excessive blueing discoloration

4. If the friction surfaces of the brake rotor exhibit one or more of the Braking Surface Conditions, the rotor requires refinishing or replacement.



5. Using a micrometer calibrated in thousandths-of-a-millimeter, or ten-thousandths-of-an-inch, measure and record the scoring depth of any grooves present on the rotor friction surfaces.
6. Compare the groove scoring depth recorded to the following specification:

Specification
Brake rotor maximum allowable scoring: 1.50 mm (0.059 in)

7. If the brake rotor scoring depth exceeds the specification, or if an excessive amount of scoring is present, the rotor requires refinishing or replacement.

Brake Rotor Surface and Wear Inspection J57

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

Note: To ensure maximum disc brake system performance, follow all instructions in the inspection procedure.

1. Remove the brake rotor. Refer to Front Brake Rotor Replacement and/or Rear Brake Rotor Replacement.

Note: Do not use a wire brush to clean the friction surfaces of the brake rotor.

2. Using a firm bristle brush, clean the friction surfaces of the brake rotor of all loose material.

Note: Do not pry against the cross-drilled holes in the brake rotor to remove loose material and debris.

3. If necessary, carefully remove any loose material and debris from the cross-drilled holes in the brake rotor with a 5 mm (3/16 in) diameter tool.

Note: Do not clean the friction surfaces of the brake rotor with chemical brake cleaners.

4. Clean the friction surfaces of the brake rotor with soap and water or denatured alcohol.
5. Visually inspect the friction surfaces of the brake rotor for the following Braking Surface Conditions:

•	High friction surface porosity

Minor surface porosity due to normal driving or single closed-course use is acceptable.

•	Oxidation of the brake rotor fibers below the friction surface, visible as vacant channels from the brake rotor friction surface

•	Excessive roughness of the brake rotor friction surface

Usually the result of intensive, multiple closed-course uses and/or high mileage.

•	Damage to the brake rotor edge and friction surface at 3 or more points exceeding the following specification:

Specification

Maximum width
1 mm (0.04 in)

Maximum depth
10 mm (0.40 in)

6. If the friction surfaces of the brake rotor exhibit one or more of the Braking Surface Conditions, the rotor requires replacement.
7. Inspect the brake rotor friction surfaces for any evidence of scoring. If any scoring of the brake rotor friction surface is present, the brake rotor requires replacement.
8. If the disc brake pads were completely worn and the brake pad mounting plate has contacted the brake rotor, the brake rotor requires replacement.
9. Perform the Brake Rotor Assembled Lateral Runout Measurement.