What causes brake pads to wear unevenly? There are several possibilities. Most of the time, its caused by ungreased or damaged guide pins. This keeps the caliper from sliding back and forth, resulting in uneven pressure on the pads. Hydraulic issues can keep the caliper pistons from extending and releasing cleanly. A sticking caliper piston can keep the pad against the rotor when you aren’t braking. Old brake hoses can flake off internally. This loose rubber can act like a one-way valve, keeping the caliper engaged on one side, leading to excessive wear. Leaks in brake lines can keep one caliper from engaging, while the other caliper works fine.
