I did a rear disc swap on my car a few months ago, and things were going good. When I did the swap I cleaned up the slider pins, and my pedal felt great. Recently, the inside of the back right rotor is only worn on the inside. The outer edge of the rotor is covered in rust (about 1/2"). I took the calipers back off today and relubed the slider pins, and drove it around pretty good. I got home, and it looked the exact same. I don't know what else could be wrong. When I did the disc swap I put new Porterfeild R4S pads in, and all the other disc surfaces in the rear look normal. Anyone have any ideas?

 

Come on, I know some of you guys know about brakes. I'm thinking my sliders are bent, or I need new bushings for them.

 

Last shot, some help would be nice.

 

There is an uncommon problem with the caliper mounting bracket.

I had little pad/rotor contact on the inside of my rear disc and so I took the caliper apart. The slider pins were lubed appropriately. It ended up that my caliper mounting bracket had deformed and was pinching the inner pad so that it cannot move even against the clamping force of the caliper piston.

Take out the mounting bracket and check the dimensions in comparison with the other side. Also, check to ensure that the pad retainer clips (2 of them: upper and lower) are not bent. Put some grease on the clips and check for adequate pad movement.

 

You're lubing up the pins with a good, high temp grease, right?

Have you checked the travel of the piston itself? I let the rear pads get too low in my old RX7 and one of the pistons came out so far, it got cocked in the bore and wore the pads and rotors just as you described.

When you reassembled, did you use the same pads? If so, they might be worn in a way that's not going to give you the proper contact even if you've rebuild eveything properly.

Good point about the retainer clips too!

If all these functional items seem ok, yah, I'd say the bracket itself could be bent. It migth be worth putting both of them next to eachother and see if there's any obvious damage to it. Who knows what kind of life they had before you got them.