DanA100

Hello,
I'm planning to replace the rear brake pads on my Audi 100 '89 this comming weekend. The car has 120K+ miles and i still have the original pads with about 2mm left on them. I have new pads now and it's time for replacement. The rotors look very good.
I tried to do the procedure myself not long ago and i had the following problem:
I couldn't push back the piston on the caliper. It went in only 2-3 mm and then it become very difficult (impossible!) to move it further in. I didn't have the best tool for the job so i blamed the problem on it. However, week later i replaced the front pads using the same tool and the pistons went back with not much trouble. Easy!
Why are the rear pistons stuck??? I wonder, Can this be due to the parking brake? Should i do something to it before i try to push back the pistons? Any hints/tricks? The calipers are Girling type and they don't look damaged or rusty or wet. Do i need new calipers if the piston is "stuck"? Or i need a better tool to push with?
Help me people!

Thanks!
DanA100

Seattle Scott

you may need to screw the rear pistons back in.

Look here http://www.20v.org/brakmain.htm

I looked in my Bentley Manual for 92 -97 100 and A6, it shows the special tool mentioned on the 20valve web site.

Ahh, the pleasures of a German car.

jnormandeau(93100CSQuattro)

Yes, you need to screw... My special tool I used was a beefy pair of needle nose pliers...

mike90q

The hand brake opperates on on some kind of a screw mecanisim. I had the same problem, even broke off a C-clamp.
Depending on weather or not you pistons are orig. or rebuilt you should be able to you an allan or hex key- as for what size I don't remember.

A pair of needle nose pliers will work but a key is faster and will keep the piston in good shape.

It's just as well to screw the piston in almost all the way instead of a bit and try a bit and try.

Also some recomend losening the resivoir cap to ease of some of the preasure....

Good luck

mike90q

DanA100

I know what you mean, the manual shows the piston on Garling Calipers to have Hex. "opening" on its surface so it can be rotated with tool and pushed(screwed) back.
Mine does NOT have this!!! It is flat, solid metal with two side "channels"(are these channels made for a different tool) Any hints to solve this?

So, should i actually do something with the hand brake adjustment BEFORE i start pushing the pistons back???

Thank you.

DanA100

jnormandeau(93100CSQuattro)

Stick the tips of the needle nose in those channels, and turn....

QCRAZY

...I bought this at my local NAPA store for a few bucks. Took a Dremel tool to it and ground off two of the prongs. The result is....

<img src="http://pictureposter.audiworld.com/1889/braketool.jpg">

....it works perfect. Stick it on the end of a ratchet and you'll get that piston pushed back in no time!!!

Good Luck!!!
---
Andrew
90 80q
91 90
95 90q

mike90q

It looks like needle nose it is.
There is a tool for leather I think that if I remember correctly is shaped just right for what you are describing.

However, maybe you should go to an automotive place, like pep boy's or something, and see if they got a loan-a-tool program. I get my speciality tool's, like tie rod tool and spring compreser etc., at canadain tire. Try something like that if you would rather instead of the plier trick.

Sorry to put down the pliers didn't have the details....

mike 90q

DanA100

Thank you all for the help...i'll try this Sunday!!!

Evilclown

The piston does screw back. Go to any parts store and ask them for a brake piston tool, it'll be a cube about two inches across with different shaped stubs on each side, and a hole in the middle for a 3/8" ratchet. This should do the trick.