Help diagnosing weak clutch

[maxsideburn]

I'm really trying to figure all of this out. The car does have a new clutch with less than 2K miles on it, a really good clutch at that (ACT 2600 or something I believe), and I know the guy that did it, he did a good job installing it. All of these problems started after I changed the master cylinder.

Right before I got the car from him we discovered that his master cylinder was leaking a little into the footwell, so after a few miles of driving the car would lose hydraulic pressure and the clutch would fall to the floor, but if we'd bled it the clutch would be strong again and work for a while. The clutch pedal was also really difficult to push.

Now once I changed the master cylinder I don't have to bleed it all the time to keep it going, but I've always noticed that the clutch slips, and when I say slips I don't mean really bad all the time, I just mean it's not grabbing as hard as it should and slips when I really get on it. Also the pedal is not nearly as stiff as before I changed the master cylinder. This leads me to believe that it is indeed the pedal that needs to be adjusted since it may not be allowing the clutch to fully engage when the pedal is released. It should also be said that the clutch pedal is currently engaging around 2/3 of the way up toward the dash, and I know that cannot be correct either.

So if the pedal is out of adjustment that badly could it really be causing the system to not create the right amount of pressure and not make the clutch engage at full strength?

At this point I'm fairly convinced it's not the clutch itself, but something in the hydraulic system, I would adjust the pedal but the VFAQ article isn't clear enough for me to follow, it's already hard enough just to get under the dash.

 

[FORMONTOYA]

I'm sure you've seen it: http://www.roadraceengineering.com/clutchandflywheeltech.htm


But yes, adjust the pedal free play that was more than likely dramatically changed when you changed the master, especially with a 2/3 travel engagement point.

 

[maxsideburn]

ok, I'm going to do that when I get home.

Still does anyone think this could be causing my problem? I mean most of the time when you're clutch pedal is soft it causes problems DISENGAGING the clutch, not ENGAGING, but for some reason since I changed the master cylinder the pedal has never been even close to as stiff as it was before. My pressure plate is really powerful, the pedal SHOULD be very hard to press.

 

[maxsideburn]

hmm, I found this on DSMtalk.com, don't know if this guy's right, but I certainly hope so, I really would like to fix this without spending any cash.

Slipping clutch FTL. Like Greenstreak said, where's your clutch engaging? If it engages too far up the pedal travel it may not be fully grabbing leading to a slipping clutch. It should start to engage about 1/2 - 1 in. off the floor and fully engage about 1/2 - 3/4 up the pedal travel.

 

[maxsideburn]

Well I yanked the seat out, crawled up under there and found out that the "insanely difficult" clutch adjustment wasn't nearly as difficult as many make it out to be. I mean really, just loosen the little nut with a 12mm wrench and turn the rod, mine even turned by hand, so no wrench necessary.

Well I think I did it a little too far, it's now engaging at about 25%-30% of the way up, when I was aiming for about 45%, but at least it's not engaging at the dash anymore.

I bolted the seat back down and decided to run to the store to get some gas, since I was almost out. I revved the motor to 4000-5000, nothing too crazy, then let 'er rip! The difference is incredible! I was hard on the accelerator all the way through first, all the way through 2nd, and then eased off as I slid into 3rd. Normally had I done that I would have slipped for a couple of second s in 1st and slipped at least half way through 2nd.

Now don't get me wrong, I still think I detected just a hint of slippage. Actually i wouldn't even call it slippage, but it didn't feel 100%, more like 90%. But then again I've been driving for a while with it slipping, so I guess now that I've got it set right I should granny it for a while and hope the disc surface wears down to normal again.

Another thing I should note is that the clutch now feels like it's "engaging" instead of just "gripping a little". There's actually a noticeable feeling of the clutch fully engaging now that wasn't there before.

I guess on a completely stock TSi I might never have noticed the difference, but mine's got performance cams, it's been bored over with custom CNC'd hemispherical pistons, boost has been cranked to 16psi, and even the limited slip has been changed to something more aggressive for drag racing. (the previous owner, my friend, rebuilt the entire engine, transmission, transfer case, turbo, and pretty much everything on the car to his specs. I've seen the drag slip showing he ran a 12.6 in it on race gas.)

 

[Defiant]

Cliff's Notes: Adjust the master cylinder pushrod.