DanA100

I did replace the rear brake pads today.
Thanks again for the advice how to push the pistons back. It was easy with the right tool from NAPA(thanks, fast!). Really easy!
However, i found a small leak on the Left rear caliper, around the piston. Not bad right now but it shouldn't be there. I already ordered a new/remanif. left Girling caliper and i'll have it in 2-3 days. The right caliper was dry and OK looking. I don't need to replace it now, right?

Can you give me any useful hints/tips on rear caliper replacement? Bleeding tricks? Hand brake adjustment? What should i look for when doing the job so i don't damage my brakes' operation?

Thanks!

DanA100

QCRAZY

...more to go!?!

It's pretty easy to change a caliper. The worst part is bleeding...IMO!! Simply pull the hydraulic line and the e-brake cable off and swap the calipers (and rip your knuckles up on a few bolts too!!!).

On the older 90's (pre-'91) you have to be sure to push the rear bias valve when you bleed them. (Using the brake pumping method) I'll look and see if you need to do that on the '93+ 90's and get back to you!!! If you have a Miti-Vac bleeding goes a lot easier (so I've heard)!!

HTH!!
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Andrew
90 80q
91 90
95 90q

QCRAZY

"SOME" of the '93+ 90's have the "bias" valve too.

I went back and checked and saw that you have an '89 100 (I was thinking it was a '92+ for some reason.) I'm sure that you have a "bias" valve in that case. On my earlier 90's it's located under the car on the right side of the rear axle; on the '93+ it's located on the left side!! Trace your brake lines!!!

It's pretty small and looks like this:

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

All you have to do is push it up. This closes it and allows fluid through. If possible, cable tie it closed!! That's about the only trick to bleeding the rear brakes!!

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

DanA100

"bias" valve the one that i have located on the caliper itself? I don't think so, but before i go under the car i wanted to ask you isn't the valve on the caliper good enough for bleeding the system??? I mean, if i let enough brake fluid flow and if i see no air bubbles comming out from the caliper opening, is the system air free? /i read that in some repair manual - non Audi/

Should i let some fluid flow out from the right side(caliper) of the car too or there is no need? Should i pump the brakes to let the fluid out or it will leak by it self??? Should i turn the car on or it can be off while doing bleeding?

I better go check under the car for this "bias" valve and see what you mean. I may not make any sense to you right now.


Thanks!

DanA100

QCRAZY

I'm must not be making much sense!!? It's not part of the caliper!!

The "bias" valve is just a lever and a spring that allows fluid to flow to the back brakes (not connected to your e-brake cable). When you stop, the back of the car goes up and "some how" this makes the "bias" valve close!! (I don't totally get it myself??) When you squeeze the "bias" valve closed to allows full flow to the rear caliper. (Like a VERY hard stop)

What your talking about (I think) is the bleeder screw. You have to use that too!! The brakes are bled the same way they are in any other car...pump the brakes, hold brake pedal down, open bleeder screw, allow fluid out, close bleeder screw....repeat until no more air flows out!!

The only difference is that "bias" valve!! If you don't squeeze the "bias" valve you won't get a good bleed...BTDT The first time I bleed the brakes in one of my Audi's I didn't touch the "bias" valve. When testing the brakes it seemed like I didn't even bleed them. SO...I decided to read my Bentley at that point (I know, about time). I did it the second time using the "bias" valve and it worked!! (I was also changing a rear caliper)

To bleed in an Audi the order goes like this:

1) Pump brakes
2) Hold pedal down
3) Push the bias valve "up" a few times
4) Open bleeder screw
5) Allow fluid out
6) Close bleeder screw
7) Repeat until no more air leaves!!!

You just have to add that one little step!! Does that make more sense???

BTW: you shouldn't have to bleed any of the other brakes. The caliper that you change is the only one that needs to be bleed!!

HTH...let me know if it doesn't. I'll try to explain it better!!
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Andrew
90 80q
91 90
95 90q

DanA100

Thanks, fast. I get the picture and i should be able to do the whole thing with no problems. The "bias" valve is something that i would overlook, but thanks to you i won't. Good thing i posted about the caliper.
I'll get the new caliper in one or two days, so i'll work on it pretty soon. I'll let you know if something goes wrong. But I doubt it, after your detailed explanation.
Thanks again!

DanA100

QCRAZY

Let us know when the job is done : - )

Seattle Scott

And make a good set of instructions, Ihave to do mine soon ;-)