Apply footbrake firmly, car pulls to the left noticably from the front. They're single piston calipers, so immediately i'm thinking stuck open caliper on the right because there's no drag from the brakes when driving, and no hot wheels. Left caliper clearly working much stronger than right.

Whip the wheels off and first thing i notice is outside of left hand brake disk is very thin whereas inside of vented disc is about what i expected. Right hand disk is about what i expected with even wear on both sides.

I took the calipers off, and both pistons pushed back in normally, no signs of sticking. Left pads are both down to the metal. Right pads are about what i expected (3-4mm).

No visible damage to pistons, or rubber seals. No visible fluid leaks or damage to either flexi-hose. No bulbous flexihoses when brakes are applied.

I'm stumped! These calipers seem fine, the brake pipes are fine, there was exactly the amount of fluid in the reservoir that i expected. ABS is fine.

Awaiting new discs & pads arriving, can't really think of what else to do but clean, reassemble and test drive?

Any tips or ideas?

Hmmm... typing that lot out has cleared my thoughts a bit...

Because it's the "floating" pad side on the caliper (vs. the piston side) that's wearing excessively, could it be that the guide just wasn't clean / greased / free enough to allow the caliper to slide enough to back off and over time it's just been subject to more wear as a result?

Any other experiences / ideas welcomed! Right now i'm thinking clean, reassemble and see how it goes...

Edited 8 April, 201016 yr by Mute

Very odd. The only thing I can suggest is that there's a single 'fast road' pad on the outside of the left-hand caliper, put on by mistake. I know from experience these give very strong braking and also eat discs. If it was the floating part of the caliper sticking (which would be the logical thing), then the INSIDE of the disc would be the worn one, I think?!?!

My experience of fast road compounds is the exact opposite; they're very gentle on discs compared with standard compounds.

Something must be rubbing, or else there was a case treatment didn't get done on the outside of that disc.