Audi Coupe 2.3 20v Quattro ( B3 version 1990 ) BRAKE PROBLEM

[Dragonzuk]

Hi Everyone

Firstly this is my first post so hi to everyone. I've had quite a few new audi's but last year i decided to purchase an Audi Coupe 2.3 20v Quattro registered in 1990. Its only done 61000 miles.

I'm having the car completely redone to try and get it to near show room condition as i've always liked these cars.

The Brake problem !!!!

So this car has the hydraulic servo system not the vacuum system. After a few weeks I took the car out and the brake pedal seem to drop about 1/2 inch but enough to engage the front brakes. So you can imagine i started to smell hot brakes after a few minutes. After this i got the car on the jack and spun the front wheels and i couldn't as the brakes were slightly engaged. After a few more attempts this happened more. The red brake warning light would also flash after startup of the car and wouldn't go out. So spoke to the car garage where the car is being refurbished and we agreed it might be the brake Accumalator. As when these lose pressure they can effect the pressure in the system. We managed to purchase one on ebay from Lithuania. We changed this but again the same problem. We have drained all the hydraulic fluid and replaced with the new G002000 replacement from Febi Bilstein. Again still the same problem.

So now we think it could be the master cyclinder so i've just ordered a replacement which is this which i believe is the correct one : Brake master cylinder

Does anyone have any other thoughts to what the problem could be. We have also changed the calipers and front brake hoses again to no avail. The rear brakes however seem to work fine.

Have i missed something or does anyone have any experience on the hydraulic brake servo system. We have thought about a brake conversion but i want to keep the car 100% original if possible.

Look forward to your comments and advice.

[Crasher]

We have a 94 S2 Avant (type 8C) on the lift gutted out for a full rebuild, painting the floor next week and I have had serious problems getting a master, still on order from Bosch



For the type 8B with the 7A engine up to 31.07.91 I get the part number as 441 611 021 A (obsolete since 2007), the S2 takes the same but a B suffix. 441 611 021 A references A.B.S part number 41864 so I think spot on with what you have found although as you are lucky enough to have an OE ATE 03.2125-3210.3 available I would not hesitate to go ATE.

If you come to the conclusion the servo is faulty, you are also in luck that these are available from Audi Tradition under part number 441 612 101 B BUT the intermediate plate that must be used, 442 611 105, is not available so if it isn't fitted to yours there will be some head scratching to do.