Haawill

1990 Audi 200 Turbo Quattro Stick Wagon - How to compress rear brake cylinder?
Does anyone know how to? I'm use to inserting a strong screwdriver or flat metal bar against the cylinder and just applying an even steady pressure and the cylinder piston moves back in so I can install new brake pads. Works fine on the front brake. On the REAR brakes what a pain! Some one told me you had to turn and push. I've taken the caliper off the car, set it up in a vice and with someone pressing down on the cylinder piston I've used pliers to turn the piston, all the while having steady pressure applied. Still NOTHING! no movement of piston. What am I doing wrong here???!1 HELP!

Jim Bush

Push as you turn, I believe autozone sells a "wrench" that catches the notches in the piston. I have always used a pliers as I put pressure on it.

Jim Bush
Holland, MI

S4for73

Pressure is NOT the answer. I used a C-clamp and cracked my rotor. It screws in and out.

Kneale Brownson

It takes pressure and turning. Best tool for the job (and well worth the cost if you're going to deal with Audi rear calipers with any sort of regularity) is in the URL.<ul><li><a href="http://www.thetoolwarehouse.net/shop/LIS-25000.html">rear caliper tool</a></li></ul>

RussB

<center><img src="http://www.harborfreight.com/cpi/photos/40700-40799/40732.gif"></center><p>
I use a tool that I bought from Harbor Freight when it was on sale (for about $20, IIRC). Of the two, I'm sure that the Lisle tool is better.<ul><li><a href="http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=40732">http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=40732</a</li></ul>

Haawill

THANK YOU EVERYONE FOR REPLYING!!
I feel like such a noob here ... Locally I bought a little square multi-use adapter ($12) and it worked like a charm. You have to push while turning CLOCKWISE to compress the piston. If you just turn it it doesn't go in at all ... I wonder why? There's also kits from K-D and Astro Pneumatic (only $48 shipped) that I'm buying as well for my other cars for future repairs. Thanks again, these forums are great!
Will<ul><li><a href="http://www.drivewerks.com/catalog/shopcart/TOOL/POR_TOOL_CAT265_pg18.htm">http://www.drivewerks.com/catalog/shopcart/TOOL/POR_TOOL_CAT265_pg18.htm</a</li></ul>

audiqv8

"If you just turn it it doesn't go in at all ... I wonder why?"

The rear brakes are also used as the emergency brakes and if the piston moved back in by just pushing them in, then the brakes would be useless. When you pull on the hand brakes lever the floating caliper is pushed up against the pads which is pushing against the piston.

Kneale Brownson

Huh???? When you pull the handbrake lever, the cables actuate little levers on the calipers that push short rods that press the piston against the brake pads. The lock on the handbrake continues to hold the pads against the rotors until released.

Here's a typical Audi rear caliper where Item 3 is the lever the handbrake cable moves, Item 13 is the short rod I mentioned and item 15 is the base on which the piston rides.

<img src="http://www.20v.org/lucas_caliper_rebuild_instructions2.jpg">

Kneale Brownson

That tool is a knuckle skinner if used where brake calipers can get corroded. The one in my other response works much better, although it's several times as expensive.

Haawill

Now this is Audi World Forum operating at it's best. Someone posts a question and less than 24 hours later all these great responses, and the best is saved for last. Thanks to all who responded, I appreciate it very much, and thanks Kneale for the diagram exploding all the parts associated with the caliper. BTW, what book is this from?