Brake noise typically comes from vibration at the friction interface. Squeal is often high-frequency vibration, while chatter can be a lower-frequency grabbing/releasing effect. Common causes include glazed or contaminated linings, uneven pad contact, misalignment, excessive air gap, worn pins or bushings creating play, and friction materials that are not matched to the brake design. Overheating can harden or glaze surfaces, increasing noise and reducing friction stability.
To reduce noise, start with inspection: ensure correct alignment, verify pad/shoe contact is even, adjust air gap/clearance to spec, and check for loose fasteners. Replace linings if glazed, cracked, or oil-soaked. Confirm the friction material grade is appropriate for the operating temperature and duty cycle; semi-metallic linings often behave differently than organic types.
If noise persists, consider system-level causes: torsional vibration in the drivetrain, warped discs, or inconsistent release pressure. Using OEM friction parts and maintaining proper clearances are the most reliable long-term fixes.
