Uneven wear usually means the friction surfaces are not sharing load equally. Common causes include misalignment between the brake and disc/drum, uneven pad contact due to worn pins/bushings, bent linkages, or sticking caliper/sliding components. On drum (block) brakes, unequal shoe clearance or asymmetrical spring force can cause one side to work harder. On disc brakes, rotor runout or warped discs can create intermittent contact and “hot spots.”
Contamination is another frequent culprit: oil, grease, or moisture may affect one pad more than the other, changing friction coefficient and accelerating localized wear. Overheating can also harden or glaze sections of lining, causing the remaining area to do more work.
Fixes start with measurement and correction: verify alignment, set clearances evenly, replace worn mechanical joints, and check disc/drum condition. Always replace friction materials in matched sets and perform a controlled bedding-in procedure where applicable. Uneven wear is an early warning—address it promptly to avoid torque loss and expensive disc/drum damage.
