well i decided it was time to do the brakes on my car both rotor and pads. I started with the right rear because the tire was already off. When i tired to set the piston back in to make room for the new pads nothing happens. I borrowed a neighbors tool that has teeth that fit into the marks on the piston and attaches to a 1/2 socket wrench. The tool works and i can turn the piston but no matter how much i turn the piston it wont more back farther. Could it be that the piston is already as far back as it can go. Then would that mean my new pads are too large to fit in the calibers. Or that the tool i am using is incorrect.... Help please

car- 1999 a4 2.8lqm prefacelift

 

have you tried using a c-clamp to push it make more?

 

Two things - use the c-clamp to put pressure on the piston while you use the twist tool to put it back in. And also (since you didn't mention it), make sure you take off the brake fluid reservoir cap so you're not pressing against the pressure of a sealed system (that's not a battle you'll win). And it never hurts to put a little penetrating fluid onto the piston threads to free them up a little.