S8 Rear caliper piston retraction
 

Trying to install new rear brake pads in the 2002 S8. I have the caliper off the rotor but cannot get the piston to retract. My heavy-duty rear caliper piston retraction tool kit is 1400 miles away, so I've been trying to use the shadetree Audi tech trick of turning the piston with waterpump pliers while applying pressure with a C-clamp, but I can't get the piston to turn at all. With or without the bleeder open. There isn't much way to support the caliper either because I haven't taken it off the hose to put it in a vise.

Any suggestions?

Stuck piston
 

I recently replaced brake pads on my 2000 A8. My RR piston was jammed also. I got it back in with both the brake tool a Vise-grips assisted with a socket/extension over the end. It seems to work now but it is not pretty. Good Luck.

I haven't done rear pads on my D2 yet, but my usual technique for all my other Audis has been to use the tip of needle nose pliers in the grooves on the piston in conjunction w/ pressure (some sort of clamp) to get it to retract. My dad just did the same w/ the rears on his C4 A6. I believe you're on the right track

Go to Napa and get the kit - I did and it made it a snap. And per Napa, just return them within 7 days and your "rental" will be free (minus your gas, time, etc.)

Did this at Autozone. The tool wouldn't turn the piston in either. I think it got cocked to one side slightly while I was first trying to get the pads off. I removed from car and put in a vise and tried to "blow" the piston out with 150 PSI of air and it still wouldn't budge. Think I'm looking for a remanned caliper.

Pity, as the bleeder open trick has always worked for me!
I just use one of those universal square block tools that take a 3/8 drive to apply the twisting action.

150psi is not a lot of pressure in a caliper. They can see 15x more than that in service.

Yeah, but I've never had one fail to pop out at that pressure. I'll have a replacement tomorrow. New pads went into the other side without a hitch.