Tolerance and Surface Finish

In manufacturing the rotor, tolerances of the braking surfaces for flatness, thickness variation and lateral runout are very closely held. The maintenance of close tolerances on the shape of the braking surfaces is necessary to prevent brake roughness In addition to these tolerances, the surface finish must be held to a specified range of 60 Ra roughness or less. A new rotor falls into this surface range, as will a rotor that is refinished exactly as directed in Refinishing Front Brake Rotors. The control of the braking surface finish is necessary to avoid problems of hard pedal-apply, excessive brake fade, pulls, pulsation's, and also to extend pad life. Light scoring of the rotor surfaces not exceeding 1.5 mm (0.06 inch) in depth, which may result from normal use, will not affect brake operation.