I was asked to work on the brakes on an '06 Pontiac G6, right rear brake pad had gone metal to metal. I bought rotors and pads for both sides, driver side was good, fairly even wear, lots of pad left, but the passenger side was indeed, metal to metal. On disassembly,I found something I'd not seen before..... The outside pad was worn completely out, the inboard pad (against the piston)was virtually untouched. Also, the Piston was stuck, it was very hard to push it back into the caliper (c-clamp) to clear the new pads. The parking brake actuator appeared to be free and not hung up. I'm ordering new caliper assys to replace at least that caliper, but why would only the outboard pad be worn out? The wheel turned freely when I started taking it apart, so it wasn't jammed, at least then. Ideas?? Thanks! AlanP
A typical brake assembly has a single or double piston on one side, when the brake pedal is depressed the piston pushes the pad into the rotor, and pushes the assembly, including the caliper, in the opposite direction. The caliper slides on pins, allowing even force to be applied on both sides of the rotor.
It sounds like the caliper seized, keeping the outer pad in contact with the rotor, this caused the outer pad to wear out. It also sounds like the piston seized as well, which means this assembly is toast and needs to be replaced. I'd bet money the other side is also in poor shape, it's always good to replace both sides.
Constant contact on the pad would have caused heat, and could have cooked the brake fluid, so that brake should be bled thoroughly. It's worth checking the hose too to ensure there was no damage. The heat could possibly have damaged the wheel bearings or broken down the grease, but that's less likely.