CarlA6

Hi, been changing the rear pads and discs on my 1999 A6 1.9 Tdi. Drivers side went straight forward but passenger side giving me trouble. The piston is very stiff to turn, (using rewind block tool), and only goes in a little then seems to stop retracting but still turns. I've had the cap off the reservoir, handbrake off and bleed valve open. Anything I'm missing to rewind it fully? Thanks in advance.

georgeb944

Harbor Freight has this tool, which has worked flawlessly for me on my several A6 cars...

Disc Brake Pad and Caliper Service Tool Kit 18 Pc

Harleyguy

Rented an almost exact match to the tool in the above link, from Auto Zone. Worked great. You need to maintain some pressure on the piston at the same time you try to screw it in. Only a couple of bucks to rent. Make sure that the piston hasn't gotten cocked in the bore and also make sure the boot isn't interfering with the piston travel. Sometimes the boot can get wedged between the piston and cylinder. The calipers can be a bugger sometimes but usually free up. I have had instances where I tightened the screw shaft on the tool, turned the piston a little and walked away for a few minutes. Then was able to put a little more pressure on the piston, walk away for a few minutes and repeat. It eventually freed up and then progressed as usual.

SloopJohnB@mac.com

Don't stomp to the floor, pump it a few times. Remove the dust boot first. After the piston is out, check for wear, corrosion, etc., make sure the outer edge of the inner face is clean because the boot has to rotate around it without sticking. Reinsert the piston while turning it. Lubricate it with brake-compatible grease or just use brake fluid.
There's a trick to putting on the dust boot...put it on the piston and turn it inside out before you put the piston in and hook it up to the screw. Then you can turn the boot right side out and work it onto the cylinder lip. The piston has to turn within the boot (it doesn't want to turn on the outside of the caliper) or else it will twist and tear the boot.

CarlA6

Thanks for all the help, much appreciated. Had another go, this time using pipe tongs on the brake pipe, with the bleed nipple open again. Slid in no trouble when turned. Not quite sure why it wouldn't go without the brake pipe closed off? Brakes working fine.
Thanks again

Harleyguy

Good news! Perserverance always pays off.

SloopJohnB@mac.com

How did you use a pipe tong?

CarlA6

May be calling it the wrong name. Two metal bars that clamp together with the brake pipe between, closing the pipe. Pipe clampy thing 😊

SloopJohnB@mac.com

Something like this one. I've got one of these and a cheap plastic version too.