Uneven Brake Pad Wear
Uneven pad wear is caused by sticking caliper pistons, hardware, and misalignment. Due to their design, the sliding pins in floating calipers often stick in their bores, causing one pad to wear more than the other. Always make sure the caliper slides freely on these pins and that the protective boots are keeping the vital lubricant in and the environment out.
The difference in thickness between one pad and the other can be dramatic. Manufacturers offer specifications for minimum pad thickness. Many pads have a slot cut into the middle that reduces vibrations and cleans the braking surface.
A sticking caliper piston seal may not retract into its bore. This leaves the pad in contact with the spinning rotor. Depending on the design, this can happen after a brake job if the bleeder wasn't opened while pushing the piston back into the caliper bore. The piston seal is now out of its groove and stuck in the bore. Check to make sure the wheel spins freely after every brake job. The piston may be applying the brake while at rest. This causes unwanted friction and great heat. Rotors can get extremely hot, and care should be taken not to burn your hand while inspecting the brake unit.