stong

Outside right now - First time changing brake pads on the RS4 and started with the right rear. I have the reservoir cap loose, e-brake off, I can't push the piston back at all with a piston tool (cheap chinese one from the local store) I even jammed on the vise grips to get more leverage to force the piston back. I'm thinking the caliper is seized. Car tracks straight when braking though. Did I forget something fundamental? Any help appreciated - otherwise I got to stick the old pads back on.

stong

Wait. Realized I need a spreader that pushes and twists. Back to the store.

ELEVENS

The force just has to be dead-on straight concentric. If it's off by the tiniest angle, the piston will bind in the bore and make you believe that the piston is a big screw that has to be screwed in, it is not.

stong

Thanks, I'll try to buy a better spreader. The one I had did seem to be pushing at a slight angle.
I did put the old pads back on and after I washed the car, the rust on the rotors didn't stay, so I assume the calipers aren't seized.

gibsonl

The kit from harbour freight is pretty cheap and works great.

stong

FWIW, I bought a well made, robust tool from metalnerd.com that pushes and twists. There are two prongs on the end that mate up perfectly with the two notches on the rear pistons. It still took some force, but once it started twisting, I was able to push the piston back. Here is the photo:

and one from the manufacturer to see the prongs:

It also came with a thin 15mm wrench to use when taking the 13mm caliper nuts off.
This tool was made 10 times better than the first one I bought (and 8x the price):