Initial Inspection and Diagnostic Overview

During the manufacture of the brake rotor, tolerances of the braking surfaces for flatness, parallelism, and lateral runout are closely held. Maintaining close tolerances on the shape of the braking surfaces is necessary to prevent brake roughness or pulsation.

It is necessary to hold the surface finish to a specified range of 60 Ra roughness or less. The control of the braking surface finish is needed to avoid problems of hard pedal apply, excessive brake fade, pulls, and erratic performance. In addition, control of the surface finish can improve lining life.

Light scoring of the rotor surfaces not exceeding 1.5 mm (0.06 inch) in depth is normal and not detrimental to brake operation.