triscadek

My left rear brake pads are much more worn, almost to the metal on the inside while the side of the pad furthest out on the rotor has at least 5 mm. of pad left on it.

Any body have an idea as to what caused this?

xsboost90

i would say that the brake line is the culprit. If the line is collapsing on itself, usually what happens is the piston will open upon braking, then not reclose itself because the line acts like a check valve. The way to check this is take the cap off the master cylinder, then take the brake line off and if brake fluid doesnt just run out easily, its prob. the line. If it does, it could also be a sticking piston. Try to push the piston in, NOT ALL THE WAY, but most the way, and see if it is dragging or hard to push in, should be smooth especially with the line off.

oh, also could be the sliders sticking, take the caliper and try to slide it in and out on the braket w/ the slider bolts on it, if it doesnt slide, that could be it as well.

triscadek

I was thinking that the inside of the caliper must be binding and just not releasing. I've just never seem one hang up like that.

Did have a brake line collapse on the inside once though just like you described.

Must be a slow Sat. night in Ohio too.

BruceWard

I am not familiar with your calipers, but I just rebuilt my 968 calipers due to crystalized brake fluid. The 968 caliper has four pistons two on each side and a crossover pipe connecting the halves of the caliper. On my calipers the crossover pipe had brake fluid crystalized in there as well reducing flow to the outside pistons. This would cause the unusual wear you are seeing.

It replaced all the seals and dust boots in the calipers, cleaned everything thoroughly then replaced the rotors, pads and wheel bearings. The car feels much better now.

Boiling the crossover pipes will clear them quickly, weedeater cable worked well to make sure the path was clear.

special tool

Its common , man. If you go to a Porsche breaker, half of the original calipers are like that - That is how I tell if it is good - look at brake pad wear on the sliding calipers. The sliding portion of your caliper is siezed/rusted and doesn't want to slide and/or the piston is shot because the boot is torn under full extension.

triscadek

Thanks, I'd never seen this on a car before but it must be a P-car thing. It just seemed odd that they didn't hang up on those gritty pins with the pad dust on them, but rather on the free end.

Danno

On the single-piston calipers, there's a sliding pin on the other side. This allows the caliper to float and center the pads over the rotor. If the grease on the sliding pin gets dried out, the caliper won't be able to slide and re-center itself as the pads wear out. The result will be that only the side with the piston will wear out. Not good for braking power either.