Brake Roughness - Disc Brake Torque Variation, Rotor Distortion and Vehicle Response

Noise and vibration related functional characteristics of the disc brake has, for a long time, been the nemesis of the design engineer's existence. New methods of measurement and analysis techniques are providing information which improves the practical assessment of a disc brake design and improves the basic understanding of noise and vibration operational aspects. Utilization of these new techniques make undesirable roughness prediction more feasible and potential solutions more rapidly identifiable.

Development of these new measurement methods involved the measurement of in-stop torque variation and rotor thickness variation (TV), as well as rotor total indicated runout. Detailed analysis of the torque variation signature of vehicle and dynamometer data indicates significant differences. These differences are shown to be influenced by vehicle suspension resonant characteristics and (in-stop) changes to both lining and rotor mechanical characteristics.