<div class="htmlview paragraph">In order to determine the mechanism of brake squeal generation, six natural squeal odes were identified and the vibrations of the rotor, backplate and lining were measured for each mode by means of accelerometers.</div> <div class="htmlview paragraph">The results show that an important factor is the phase difference between the change in friction surface displacement and the change in lining thickness. In the two high frequency modes, it was confirmed that the exciting energy is generated by fluctuations in friction force due to fluctuations in surface pressure. And it was concluded that squeal generation is dependent on the ratio of change in frictional force rather than in the <i>μ</i>-v characteristics.</div>