Techno Duck

Drove the 951 briefly today and have noticed the clutch slips in 2nd through 5th gear when really getting into the boost. It only happens when the car is at normal operating temp. I can have the car running 5-10 minutes and hit full boost in any gear and it dosent slip. After that period it starts to slip.

The clutch was replaced back in 2003 but has less than 10k miles on it. Granted its also seen about a number of DE's in that time..but i know the last two owners of this car knew how to drive it.

I know there is some adjustment which can be done with the clutch pedal, but will that have any effect on the clutch engagement? Specifically can that have any effect on the slipping only when hot? I do not see any oil leaking from the rear of the pan or flywheel cover, nor do i have any oil spots on the drive way. Also no loss of coolant from the heater control valve. If the car had maybe 20k miles on it i can see 'maybe' the clutch being toast, but i find it hard to believe with less than 10k miles on it, even with the DE's mixed in.

The master and slave cylinder were both replaced about 800 miles ago by the previous owner at a Porsche specialty place, clutch pedal comes back to height and brakes feel fine..so i dont think its air or anything.

And gosh do i love boost....

KuHL 951

It sounds like you've done everything to eliminate the possibility of anything but slippage. I feel the pedal adjustment is pretty critical on any 944. Did you adjust the freeplay when you replaced it with a new clutch and has it been adjusted since? If there is no freeplay in the pedal the clutch isn't fully engaged and it will slip and wear out fast. This happened on my son's Acura we did and it's my fault for not taking making the adjustment and I ended up I replacing a disc within 7K miles. Even if you do nothing else it's only a very uncomfortable adjustment that takes about 15 minutes. If the allowance for less travel isn't made at the time of installation for a new PP and disc it might have been slipping from day 1. Try the adjustment first and see if it helps; if it has been slipping for very long it will be glazed and that's hard to resolve without just waiting for new material to work it's way to the surface from everyday use. I'm thinking that both clutch components are OK from your description.

The only other possibility is that you are making too much power but we all know there is no such thing as too much power.

Techno Duck

Thanks for the info Steve, Ill play around with the adjustment in a day or two. The car is defenetley not making to much power.... autothority stage 2 chips, LBE and a full SFR 3'' exhaust with no cat. I figure 240-250whp on a good day.

KuHL 951

The feeling of clutch engagement is sort of subjective. When hydraulic components are failing it never disengages smoothly and shifting is much harder. When freeplay in the clutch isn't there, the clutch is never really completely engaged. As long as you are confident that the slippage isn't a fluid contamination problem the pedal adjustment is your best 1st choice for tracking down the problem. One more question: Can you see the tach actually climb too fast without forward progress? That is important in finding the source of your problem.

Techno Duck

Hey Steve, yea the tach jumps up and the car dosent really surge forward. If i lift up briefly it will 'catch' and accelerate..but if i get to hard on the gas again it will start to slip again. Im confident the clutch disc is alright as its only slipped very briefly for a moment before i immediately let up off the gas. I was off boost pretty much the entire ride home....felt like i was driving my n/a . Which is actually funny, the turbo's power delivery feels alot like my n/a up until 2800rpm or so. Then its a whole other ball game The car has been lightly used since the slave / master cylinder was changed, mostly going back and fourth to the train station.

One thing i cannot verify yet is that when the car is cold (and clutch dosent slip) it feels like the engagement on the clutch pedal is much closer to the floor. I noticed when i was pulling out of a spot that the clutch engagement was literally at the last inch or so of travel when the car was hot and it was slipping. Im not sure if it actually changed or not and wont be able to until this weekend when i get a chance to mess around with it.

KuHL 951

IMO try the free play adjustment first and see where that leaves you. There's only about an 1/8" of slack you want in the pedal before resistance, at least that's how I do it. It's part of any clutch job that's done right. I know that I can depress mine and shift with about 3-1/2" - 4" of pedal travel, I even thought of doing one of those BMW pedal stops since I really didn't need to push it that far. The best news is you probably won't have to drop any components if the adjustment works. Clarke's has a good write-up as I'm sure you know. Getting under the dash is the hardest park to do the adjustment. Hope it works for you.

Techno Duck

Ah yea, i did quiet a bit of work on my n/a removing a old malfunctioning alarm. Not looking forward to the extremely awkward positioning, but atleast i just bought a set of stubby gear wrenches that should come in handy..

tommye

It definitely sounds like pedal adjustment - I had the same problem once.
If the freeplay isn't large enough, there is nowhere for the hydraulic fluid to escape in case of thermal expansion and pressure will increase in the system thus disengaging the clutch somewhat.
It sounds just like what's happening with your car as it warms up....

Good luck !
Tommy

Techno Duck

Just an update, had a chance to adjust the push rod. Clutch no longer slips . Was much easier than i expected and was happy to see a straight shot to the push rod. Unlike my 944 which has a mess of wire due to an aftermarket alarm install.

Took a nice test run..gotta say i love boost .

DLS

how do you adjust the push rod?
my car is slipping sometimes at full boost and high gear.
noticed another strange thing last night when i parked the car i the garage, the car continued moving slowly forward after i put the clutch pedal down??
tried one more time and then the car didn´t move forward.
is my clutch going bad?

CarbonRevo

Not 944 related, but I didn't like all of the free-play in my trucks clutch, so I adjusted the pedal some to cancel out this freeplay so it has resistance when you hardly even touch the pedal.

Do I need to go out and put some free-play into my pedal? I have noticed over-time since I did it that my truck shifts differently. I have roughly 23k miles on the clutch, and maybe 2k since I adjusted the pedal. I never thought anything of it...

Tay-Tay

The second part sounds like your clutch master and/or slave is going, bleeding may give you a bit more time but be ready to buy both, happened to me like that.

As for the slipping I would bleed the system and adjust the freeplay per Clark's Garage as well as check the clutch wear through the clutch inspection port.

If your clutch master and slave are going I wouldn’t think it would slip b/c of misadjusted freepaly, since failing clutch hydraulics would make it difficult to disengage the clutch, not positive about that though.

Taylor

DanaT

Why is that my 951 seems to be suffering all of the problems? Actually, its not bad. It just smells like gas and when I hammer it in 2nd through 5th, it is doing the same thing.

I need to get under and look at it. I cannot rule out fluid contamination as my car does have an oil leak (the ONE time I took it to a shop, they didn't have the right tool and marred up the front of the crankshaft by using vise grips instead of the flywheel lock). I get oil leaking from the front main. I have just lived with it. However that could be contributing, but I doubt it. Why? The oil seal damage occured 7-8 years ago. It has just recently started with the clutch slipping.

The clutch has bene abused somewhat (some drag racing, etc). I think I have just worn the clutch out.

Now it is time for me to decide if I want to keep the car. I don't want to pay shop prices to keep a toy running. I don't have tons of time to spend working on the thing for the next few years (full time work / travel with work / and grad school).

Maybe its time to upgrade to one of the high end 700ft-lb clutches??

-Dana

Techno Duck

Dana, you can do a very quick feel test of the clutch pedal. Push on it with your hand..it should have a very slight amount of play before you feel any resistance. I did the same with mine prior to the adjustment (and slipping clutch) and it was solid as a rock. I adjusted for the factory called for play and its fine now. Over 200 miles so far...lots of hard boosting .

DanaT

I tried looking on the clarks garage page and didn't really see what the adjustment technique was. Do you have a link on how to adjust this?

What is strange with adjustment, is why would it just now start? It has ran fine for years with no adjustment? Of coarse it could need adjustment based upon wear.

-Dana