What Causes the Noise from the Lower Control Arm When Braking in an Audi A4L?

[OCollin]

Audi A4L produces noise from the lower control arm when braking, and the common causes include the following: 1. Noise when braking in a new car: The brake pads and brake discs of a new car have not been fully broken in, so they may sometimes emit a "squeaking" friction sound, which is normal. The noise will naturally disappear after some use. 2. Noise after replacing brake pads: After installing new brake pads, incorrect installation may cause noise. Common installation errors include installing the brake pads backward, with the metal side touching the brake disc, leading to noise. 3. Noise due to brake disc issues: Prolonged use can cause deep grooves on the brake disc surface or deep steps on the edges. Uneven contact between the brake pads and the brake disc can produce noise. In this case, the brake disc needs to be replaced or polished using a brake disc repair machine. 4. Noise caused by sand in the brake disc: If foreign objects like sand or small stones get between the brake pads and the brake disc while driving, the brakes may emit a sharp hissing sound. Continuing to drive normally will usually dislodge the sand or stones, eliminating the noise. If the noise persists, the wheel may need to be removed to extract the debris. 5. Noise during hard braking: When braking hard, if you hear a "clicking" sound and feel vibrations in the brake pedal, this is a normal phenomenon caused by the activation of the ABS system.