Clutch question

B6/7 S4/RS4
#1

So earlier this afternoon, I did a 3rd gear WOT run and shifted into 4th and continued the WOT for a little bit and then let off, switched into 6th and then my clutch pedal wouldn’t come back. It was still engaged, I was able to pull on to the shoulder, at which point I continued trying to play with it but the pedal still wouldn’t come back up. I went into neutral but couldn’t get back into gear (the pedal was still down). I then pulled the pedal back with my hand and I was then able to start using it again. I therefore merged back onto the highway and it seemed ok again.

Then, 20 minutes later I stopped for lunch for about an hour. After lunch, someone else drove the car briskly. The other driver didn’t notice any issues. I took the car back and 20 minutes later of more brisk driving, the problem was starting to slowly come back (I could feel the clutch pedal begin to not come back as quickly as it should although it never got stuck like the first time).

What could cause this? A bad slave cylinder? Low pressure in the lines?

Thanks.

#2

how’s your brake fluid looking? Age, color, fluid level.

#3

There is a rubber hose return that comes off the slave cylinder. It loses it’s elasticity over time and can cause the symptoms you are describing. Usp motorsports sells a metal slave cylinder and a steel line or braided line. I bought this for my car but haven’t installed them yet. Others have reported this is was the best resolve for the issue. I’d do some investigating before throwing money at the problem. Check what beem suggested first and then go from there.

#4

Makes perfect sense. Thanks!

#5

sounds like a weak slave to me. Something deffinitly sounds weak in the hydrolic system

#6

Yeah, it’s now happening at WOT above 5k rpms even when the car hasn’t been thrashed around beforehand. So I think I can rule out overheating. How much do slave cylinders go for?

(I also bought the SS line for the hell of it as it’s not all that expensive but I don’t think it’ll fully fix this problem).

#7

Any update on this? I actually had this happen tonight while me and my buddy with his viper were playing around.

I made a strong 2-3 (or maybe 3-4) shift and thought the pedal hesitated as I came off but didn’t sound like it slipped or anything. Then a little further down the interstate I did a 3-4 accel run, and on the shift the pedal engaged but stayed just above the engagement point. (i.e. no play before engagement). In the next min or two, it work back out and felt normal. I did a 1-2 near my apt a bit later and it felt fine but didn’t want to test it anymore b/c I didn’t want to be stranded on the interstate.

My slave was replaced 15k ago, and brake fluid was flushed ~1.5yr ago around 30k ago and was right on the max level. My clutch as felt perfectly fine and solid ever since it was broken in and fine after the motor pull 6k ago as well. So I was pretty shocked by this tonight. Just thought I’d see what you’d found out. Hoping it’s just a fluke.

#8

Not yet, my mechanic is on vacation for the next week so when he’s back, he’ll address it. In the mean time, I just can’t do a WOT 5k+ rpm shift. Annoying but I don’t do those ALL the time :slight_smile:

#9

I just put a new slave in my car yesterday for similar reasons. I have done I couple of 5000+ rpm pulls in various gears and so far all appears to be working. I wanted to run it hard today, but we have snow here so I probably won’t take the S4 out.

#10

weird because this appears to be happening only to supercharged guys.

Axel, Speed, GolfTeam : What stage clutch are you guys all rocking?

#11

I have the JHM Stage 3 kit.

#12

Speed, you did this b/c you were actually having a problem, or just as a precautionary?

Headers make it a BITCH to do transmission work. I took it to one shop for them to bleed the slave, they took one look at the headers and said it can’t be accessed. Luckily I did a good job myself, I just wanted them to double check it.

Saki, I’m Stg4 with LWFW. And this is the first time I’ve ever noticed it happening. I’ve been making pretty solid shifts on it for a while no problem.

#13

I was having an issue with the pedal not coming back up under hard runs. It is fine under normal/spirited driving. It literally just started this week.

#14

Interesting it’s just with us S/C guys. Clutch/FW was one area I thought I was set for good. Wondering if what horsepower is talking about has anything to do with it.

Also interesting we’re only seeing it in 3-4 shift, maybe combination of less RPM drop which means higher power level at engagement as well as probably the fastest shift?

Is it as simple as the auto adjuster getting pushed all the way out? B/c if so, I’m fine with that lol. Better than a trans pull. My last clutch was like that anyways after the abuse with the beta LA and the couple times I used LA on accident with esp still on.

#15

could be that they are revving faster than the N/A cars

#16

faster than 91gl, jaybquick and the various nitrous cars?

#17

The nitrous cars was one of the first thing that came to mind. But I don’t know how the spray controller is cutting on/off during shifts.

91gl if anyone should be the one to see problems, and then Jay of course. It’ll be interested to see what info surfaces.

#18

Wouldn’t it be more the stage 4 clutch being harder on the slave cylinder (which is 6 years old)? I’m not very mechanically inclined so I may be way off.

#19

Quick update - the new slave didn’t fix the problem. The clutch pedal still stays down for a bit after WOT pulls in 1st, 2nd and 3rd (it will eventually pop back up if left alone). To note, I can still shift the car, but the engagement is instant. Once the pedal is pulled up, it works fine. Also, I can gradually accelerate in 1st and 2nd to red line and I do not have the issue. It only happens when I am WOT above 5000 rpms in the lower gears.

#20

Interesting. So a new slave DOESN’T fix it eh? Yeah, my problem is identical (although it also happened to me in 4th gear).

Hmmm…any knowledgeable folks here have an idea?