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Brake Disc Surface and Wear Inspection

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

1. If the inboard friction surface of the brake disc is not accessible, reposition and support the calliper 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 disc with methylated spirit, or an equivalent approved brake cleaner.
3. Inspect the friction surfaces of the brake disc 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 disc.

•	Cracks and/or heat spots

•	Excessive blueing discolouration

4. If the friction surfaces of the brake disc exhibit one or more of the Braking Surface Conditions, the disc 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 disc friction surfaces.
6. Compare the groove scoring depth recorded to the following specification:

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

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