Got a brake pad wear warning last week. Put the car up on jacks, pulled all the wheels, and discovered that yes, my rears are definitely due, but at all four corners the inner/inboard pads are much thinner than the outboard pads and the rotor surfaces are all "dished" on the inboard side (with a ridge of material standing proud of the friction surface at the inner and outer edges). I haven't pulled things apart and gotten a really close look, but the wear pattern seems the same on the left and right sides. (Fronts are newer with plenty of material left and less dishing of the rotors).

My first guess is that my caliper slides (and probably pistons) are gunked up and need some TLC, but with the wear looking fairly consistent all around they would all have to be pretty equally gunked up (comparing left and right). I guess that's possible (maybe even common), but I'm wondering if there could be some more central problem in the braking system that is causing all four inner pads to press harder than the outer pads. I can't think of anything....can anybody else? I'm going to pull the rear calipers in the morning and take a look at the slides and pistons, and wondering if there's something else I should take a close look at while I'm under the car.

FWIW, my braking performance has been just fine - solid consistent deceleration whenever I call for it, no judder or noises, no suspicious drops of fluid on the garage floor or anything, just this odd wear pattern all around.

 

Your calipers most likely need to be thoroughly cleaned and lubricated. They are probably dragging and wearing down the pads. Even if the pins look OK, they can be getting hung up.

I used to perplex over this issue when I was younger. Then I just started thoroughly cleaning and lubing calipers any time I found uneven wear or knew a caliper was dragging. Fixes most of these issues, unless the caliper is trashed and needs to be replaced.

I figured all this out on motorcycles where a dragging disc brake is MUCH more noticeable than a car. I drove my truck with a seizing rear caliper for months before I realized. 6000 pounds and a V8 masked it dragging for a while.

 

I had a dragging rear caliper on a Lexus recently. The symptom? The smell of the heat it generated.

 

That's pretty much what I figure, and I've got new slide bushings and piston seals&boots on the way (along with pads, rotors, wear sensor and a windback tool). Doesn't sound like there's any other obvious culprit I should look at while I'm in there, but I figured it was worth asking the forum just in case there was something weird I hadn't thought about.