3L33ter

I searched and searched but I only found some info for the B3. The B4 is different! At least this is my conclusion, since the B3 procedure doesn't really work on my B4. The brake booster is TOTALLY in the way, and from what I read, the B3 does not have a brake booster so there's a lot more room.

So I thought I'd contribute this little walkthrough on how to remove and replace the clutch MC on a B4 since I just did mine and it took me way too long. Most of the time was just wasted trying to figure out a method.

Please note that the general wisdom is to replace the master and slave cylinders at the same time, since they likely have the same amount of wear and age.

Tools:
screwdriver
turkey baster
10mm open-end wrench
11mm open-end wrench
12mm open-end wrench
6mm allen tool of choice
2 spare m8 bolts, about 3" long
assistant

1. Siphon out fluid from the brake fluid reservoir until the fluid level is below the nipple on the side which feeds the clutch master cylinder. I use a turkey baster.

2. You want to get as much fuild out of the master cylinder as you can. I was also changing my slave cylinder so the line was disconnected down there and all the fluid dripped out. In general, I would say open the bleeder valve on the slave (first connect a tube routed to a bottle/bucket) and let it drip dry. Maybe blow into the brake reservoir to help the flow.

3. While you're under the car, pop the clutch hardline out of the white plastic holders along the body.

4. Disconnect the master cylinder hose from the side of the brake reservoir.

5. In the cabin, remove the kick panel under the steering column. If yours is like mine, it is held in with a few 8mm bolts.

6. Slide back the driver seat all the way. Get 10mm, 11mm and 12mm open-end wrenches, a socket wrench with about 18" of extensions and a 6mm allen socket, a medium screwdriver, and 2 spare bolts m8 (13mm head) about 3" long). Lie down into the footwell and take a look at the clutch pedal.

7. Use the screwdriver to pop the clip off of the pin holding the master cylinder clevis pin to the pedal. Take out the pin.

8. Loosen the 10mm locknut on the MC's shaft (you have to counter-hold the 11mm base of the shaft). Move the clevis off of the pedal and unscrew it from the MC.

9. Unbolt the 2 allen bolts securing the master cylinder (you can stay lying down).

10. Screw in the 2 long bolts you brought, at least 3-4mm, in place of the 2 allens you just removed. These bolts will keep the MC from rotating when you try to crack loose the hydraulic fitting.

11. Slide the MC back towards you. You may have to yank hard, but since the hardline is freed and the hose is disconnected, it should be relatively easy to pull. Pull it in until you can see the hydraulic fitting and you have enough room to get a wrench on it.

12. Place a couple of rags under the fitting so when it's open and it drips, it hits the rags. Use the 12mm wrench to crack loose the fitting, (now you can remove the long bolts if you want) and unscrew the fitting all the way. It will take a while with the limited space, just work slowly and don't let your hand cramp up.

13. Remove the 2 long bolts you put in, if you haven't already. Extract the MC and throw it in the garbage / over a cliff / into the fires of Mordor, depending on how frustrated you are. While pulling it out, you will pull the hose through the firewall too.

14. Transfer the hose and the locknut to the new MC.

15. Put the MC into place, feeding the hose through the firewall first. You may have to go a few inches at a time, and get up and check the engine bay (and make sure the hose is routed the right way).

16. For this part, you will need a helper (IMO). Have your helper stand at the driver side of the engine bay, and stick their arm in behind the battery and reach back toward the clutch hard line. They need to push the hardline into the cabin and keep pressure on it. You will be inside lying down, and trying to get the hardline fitting screwed into the MC. You'll need to push the MC forward against the hardline and try using your fingers, tools, anything, to screw the fitting on.

17. Once you get the threads started, take your time and screw the fitting 99% of the way on. Put in those 2 long bolts again. These bolts will not only stabilize the MC so you can tighten down the fitting, but they will also hold the MC at the right angle so when the fitting is tight, the hardline and MC are oriented correctly to each other. With the 2 bolts in, tighten the fitting.

18. Everything from here is the reverse of removal.

19. Bleed the clutch system.

20. Don't tighten the clevis locknut until after you bleed the clutch. Then, adjust the clevis to put your pedal engagement point where you like.




If anyone has corrections or input, please chime in! I did this job a few hours ago and I wrote these instructions really quickly (while still fresh in my mind).

nrh90

Wish this was around when I did mine 3 months ago! I spent forever figuring out how to remove the damn thing too. I ended up taking the battery out so that I could get an arm in easier (around step 16). Not really necessary though.

3L33ter

Thanks! Yeah, this job seriously took me about 3 hours, and I still haven't bled the system. Normally a clutch MC takes me half and hour, but I guess an Audi 90 is anything but normal, LOL.

Lago Blue

indeed. Thanks for that, sir.

Luxus Panzer

U should add this here....

http://forums.quattroworld.com/9080/msgs/17522.phtml


we are working on building a excellent FAQ

3L33ter

Done. I wish I could add this to this site's tech page too.

Lago Blue

From the top of the tech section:

"...then you are strongly encouraged to submit that information for a Tech article. Submit articles by e-mailing to staff@audiworld.com."

Does that not work?

3L33ter

Cool, did not know that. Email sent!