Brake Rotor Surface and Wear Inspection: Notes
Brake rotors are manufactured with close tolerances for thickness variation, flatness, and lateral runout, but pits and grooves are created in rotors during usage. Lack of uniformity of the braking surfaces of the rotor can cause inadequate braking and a pulsating pedal during braking.
The surface finish of the rotor is also important because an unsuitable finish of the rotor can cause pulling and rapid wear of the brake shoe lining. Light scoring of the rotor surfaces is acceptable if the scoring does not exceed 0.40 mm (0.016 in) in depth. Scoring measurements can be made with a commercially available brake micrometer. If a rotor does not meet the specification, refinish or replace the rotor. Refinishing of the rotor should only be done with precision equipment.