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audi_dude
06-10-2007, 04:24 PM
3 miles out of the house today as I was pulling into a gas station, I felt the clutch pedal sink a bit. IE: the pedal was further forward (towards the firewall) than usual, but it still worked -- enough to get me to the pump. I stuck my foot under the pedal and pulled it up, and it seemed mostly okay, but when I was leaving I could not get it into gear. The clutch was not disengaging. The pedal felt much lighted to press in and also does not come back up on it's own. So I had it towed back home.

Car is early 1998 B5 A4 1.8T, FWD, Manual, 147k miles.

Some quick investigation tells me that this is a direct-cable system (not hydraulic), so the spring in the pedal is probably provided by the pressure plate. So I'm guessing I have a pressure-plate or cable problem. Actually it feels like a collar or something on the cable has slipped.

Anyone have some insight on this? My other 2 cars are already down for maintenance/construction, so now I'm stranded until I get this fixed.

Much thanks,
-Neil.

audi_dude
06-10-2007, 04:56 PM
Actually, I'll take that back -- according to Bentley I have a hydraulic clutch system which seems to use brake fluid. Not sure if one of the cylinders is dead or what. Any insight, leads, starting points, etc appreciated. Thanks.

frostracing
06-10-2007, 06:27 PM
you probably have a bad slave cylinder. When mine went out is acted like that. It is the part that transfers hydrolic pressure from the master cylinder to a built in rod that actually pushes the clutch fork. If the leak is bad you should be able to tell by looking at the master cylinder resivor. That is where your brake fluid is. The clutch shares that with your brakes.

Burntaudi
06-10-2007, 06:45 PM
Could be the clutch master also. Mine blew a few years ago. Clutch pedal went right to the floor fluid all over the second firewall.

audi_dude
06-10-2007, 07:37 PM
Brake fluid level seems normal -- just a bit above the seam on the reservoir and about half-way between the min and max marks. Not sure if it was higher previously though.

Interestingly, I just drove this car from Florida to Texas and back last week, and thought I was smelling something nasty -- but only infrequently. I thought it smelled "chemically" like brake fluid or power-steering fluid, and during the drive I was regularly reporting to a friend on the phone trying to narrow it down. At one point I thought it was happening only when I kicked up the stereo. ...yes, seriously. But I could not reproduce the smell on the return trip. And for the 2 days since I got back, all has been well.

I'm guessing that these are related events and I just sniffed the fluid in the brake reservoir and think it is what I was smelling previously. So if I could smell it in an enclosed car, would that indicate master cylinder? From the diagrams in Bentley, it seems like the MC would be near the brake booster, but I can't actually find it there. Could it really be by the pedal cluster?

So how would I determine if it's the master or slave? Or should I spend the extra $80 and replace both? And then how do I know it's not one of the lines between the two. My prob here is that I have another car scattered in pieces all over the garage and I'm not allowed to work on the car in my driveway, so I am not sure how to get under it to inspect for leaks etc. I may have to find a shop if it's not a simple-ish fix, but I shudder at the possible labor costs.

BTW, yeah I know I'm lucky this didn't happen while I was in the middle of Louisana or Pensacola, etc.

frostracing
06-10-2007, 08:34 PM
it could be either. I have replaced slave cylinders on a 1.8T and a 2.830v. The 1.8t is much easier and shouldn't take a shop more then an hour to r&r and then bleed the new one. I've never done the master cyl. so I don't know what your in for with that. You should have someone depress the clutch pedal while you watch the slave cylinder. It is located on top of the trans just inside the firewall. It's not easy to see, but you can see it.

audi_dude
06-10-2007, 10:47 PM
Thanks. Problem is getting the car up on jackstands -- no-no in my neighborhood. Can I see the slave cylinder clearly from the top if I remove the coolant overflow container? BTW, is this a simple regular-tools (sockets, wrenches, allen-keys, etc) job, or do I need any Audi-type special tools or triple-squares, etc? I'm asking because if I do decide to attack this myself, I won't be able to run out for any tools as I'm pretty much stranded for now.

audi_dude
06-11-2007, 10:06 AM
Shops and dealers want $700+ to $1100 for parts and labor, and parts can only get here by end of week. Looks like I'll be doing this myself. If anyone knows how to test whether the Master, Slave or some line in-between is bad, please let me know. In the meanwhile, I'm going to inspect for leaks...
Thanks!

Euro-Tuner
06-11-2007, 10:39 AM
you dont need ant special tools for the slave cylinder, Im not positive about the master, I removed the slave when I dropped my tranny but Im not positve if it is possible to access it with the tranny bolted up, if not, your in for a big job...not to scare you off, but if your gonna tackle this, you had better know what your doing, and be careful, the tranny if heavy, and it is a tough job from the ground

frostracing
06-11-2007, 11:20 AM
I replaced it on a 1.8t from the top. I agree, removing the trans is not something that should be taken lightly. It has been a while and I don't have my 1.8t to look at anymore but I'm pretty sure it is only on by one torx bolt. Maybe a 30 or something close. The hard part is getting it back into the trans because it has a rubber cover that makes it a really tight fit. Then you just bleed it and go. I would say for under 100 it is worth it even if you have to replace the master. It shouldn't take longer then two hours but without really knowing your mechanical abilities I can't say for sure.

audi_dude
06-11-2007, 12:24 PM
One of the quotes I got was 3hrs for the Master and 1.5hrs for the Slave, so I assume no trans dropping is necessary. Also Bentley does not mention dropping the trans (although their manual is a little odd at time as it assumes you've been following the procedures in the previous pages for something else). If dropping the tranny is required, I will be taking it to a shop.

I was just investigating a bit more and the MC seems easy to replace as long as I can get easy access to the bolts/lines. So far the left bolt (6mm allen) on the MC (at the pedal cluster) seems difficult to reach, so I'll have to get some series of flexible joints and extensions in there. Still no biggie.

I'm not worried about my abilites :) I've done all the work on this myself for the last 100k miles (since the warranty expired), and I've built engines (mostly Fords) from the bare blocks. But this Audi always worries me because of special tools and really difficult access at times. For example with my recent turbo swap on this car, there is no way I could've just removed the oil line under the turbo as Bentley said, without first removing that line from the oil-pan side.

Thanks for the tips. I'll report back as it progresses.

audi_dude
06-11-2007, 01:49 PM
Uh-oh... here's another interesting thing... I just noticed that the brake fluid reservoir has a crack at the top -- sort looks like it's brittle from age and not just a single crack, but multiple cracks in about a 1-sq-in area at the back of the reservoir. I doubt that a bit of fluid leak would cause the symptoms I have (and there's no signs of fluid leaking), but I thought I'd post here in case someone can correlate this with the issue somehow.

I just ordered the brake-fluid reservoir, the MC and SC, so hopefully that'll solve the problem. According to PureMS btw, the SC is much easier to change than the MC, so that's great to hear.

Thanks again,
-Neil.

audi_dude
06-13-2007, 10:36 AM
Started the MC swap, but having a small issue. Help requested please ...
http://audizine.com/forum/showthread.php?p=1700539

audi_dude
06-13-2007, 12:52 PM
Update. Figured out the MC fitting thing, swapped the MC, and all works again. The clutch works and the car drives!!! I also swapped out the brake-fluid reservoir while I was at it. But it feels like it needs bleeding. I will also swap out the SC (slave cylinder) when I get my garage free again, and bleed the system then.

BTW, for those who may need it, DOT4 brake fluid is usually not available from generic auto-parts stores, but motorcycle shops carry it. DO NOT use DOT5 thinking it's better, as it's silicone-based fluid and not compatible.