Check for thickness variation by measuring the rotor thickness at four or more points around the circumference of the rotor. Use a micrometer calibrated in ten-thousandths of an inch. Make all measurements at the same distance in from the edge of the rotor.

A rotor that varies in thickness by more than 0.013 mm (0.0005 in) causes brake pedal pulsation and/or vehicle vibration during brake application. Refinish to specifications or replace a rotor that does not meet these specifications. C3500HD Models must not exceed 0.25 mm (0.001 in) thickness variation.