BMW E46 Brake Vibration: Causes and Fix

The cause is not always the brake discs. Often the fault is play in the front axle, especially worn rear bushings of the lower control arm. Another common cause is a sticking brake caliper piston, which presses on the disc unevenly.

Only for a while, if the real cause is play in the suspension or a sticking caliper. The vibration then returns in about a month. Measure the disc runout with a dial gauge before replacing, and check the rear bushings of the control arms first.

Check the caliper slide pins and piston: clean, renew the seals and service them. Clean the wheel hub surface of rust with a wire brush so the disc does not sit crooked. A loose wheel bearing or an out-of-round wheel can also cause vibration.