Ok, as described before, I have a slightly “scratchy” rough clutch pedal towards end of travel. It just feels like; a rusty cable in need of lubricating. A diagnosis by Porsche workshop was cylinder booster at the pedal. Wrong. They’ve changed it and this scratchy feeling remains. When ignition is off there is no scratchy feeling, clutch firms up but it is press-able after 30 presses and smooth. Clutch engages halfway up the pedal. Car now has 60,000 miles. Now they are saying it is another cylinder with a canister attached to it located above the gearbox. My Indy-mechanic in London says it’s probably clutch fork as they dry up with heat so time for new clutch. He doubts Porsche’s workshop diagnosis. Any ideas, I just want to nail the problem and get it over and done with.

 

It could be one of a couple of things, but first You clutch hydraulics consist of:

Clutch master (at the pedal)
Clutch lines with unions attaching them
Clutch slave cylinder at the gear box
Clutch hydraulic accumilator (ball that screws into slave for pedal "assist")

It's very common for the hydraulics to fail over time, as they wear out. Mainly the accumilator and the slave are the culprits. However, you could have an issue with the needle bearings in the clutch fork/release bearing assembly binding up. However, I'd try the clutch slave/accumilator first... MUCH cheaper to deal with... If you do remove the tranny, I'd recommend swapping the clutch hydraulic assembly to the GT2 parts... Gets rid of all the list of problem parts above.

Mike

 

I am putting in the GT2 stuff. Per Steve K. at IA (site sponsor), porshephd, the car will then have clutch feel that is very similar to a gt3. Having been in a gt3, I very much liked that idea....have always felt the tt boost is a bit too much (good in town/heavy traffic though). My clutch kit came from UMW and has an 954RS lightweight flywheel.

The switch to the gt2 set up makes the all-too-common problems I and Mikelly (and many others..) have had with the accumulator/slave in theory a thing of the past.

The gt2 stuff uses DOT4 brake fluid and not pentosin. I feel that in a safety issue as the latter is flammable. I got a kit from Steve K. for all the parts. Just an FYI. It will go into the car in 3 weeks (going to DAS for some go-fast changes.....

John D of speedtech did the change and has posted about it. You could email hime questions about it as I think it is the way to go, but have not actually installed it. He has had it for a long time and remains positive afaik.

Parts ~$1000.

Labor: 3-5 hours. Varies by mechanics experience. DAS or SK at IA, likely 3-4. New to the job good indy, likely 5. Porsche dealer...double that if they'd even be willing to help as it is not OEM strickly speaking....

If you read t2's posts here or on rennlist, he has 200k miles on his car (or about that) and has had 5 slave cylinders. The labor on my slave was 5 hours and the pentosin and accumator parts added up to about 500 dollars. I had help from a board member who happend to have a spare (tells you something about how often these let go....). So, the gt2 upgrade for me is worth it as I plan to keep the car a long time.


JB

 

Thanks guys.

So, with clutch master replaced - is this it - part no.: 996 423 171 52? That’s what they changed.

Is there a way to pinpoint next item most likely to be; clutch slave cylinder at the gear box and or clutch hydraulic accumilator, or needle bearings in the clutch fork/release bearing assembly binding up? I really don’t want to change it all if I don’t have 2.

Also wouldn't the symptom for a faulty slave be leak rather than scratchy feel?

How much stiffer is GT2 clutch setup should I go down that route? What happens to steering power assist aren't they both part of the same system?

 

Steering stays pentosin (the same).


Call Steven K. at IA and talk to him. What I did. He has always been super to help (and is the PCA national turbo tech guru). The parts ended up coming from him. One major part is machined (EVOMS) for the record, so the main design and implementation is EVOMS. They have a website and they are good to work with. My story is that Steven gave me the idea first a long time ago when I was having trouble...suggesting this as a long term "fix." My buying from him was to give him the small profit from wholesale to retail as a "thank you." Just my 2c.

It is stiffer. All I know is that it feels like a gt3 (Per SK) and supposedly makes clutch engagement "much" better....you can feel more is what I have heard.

John D? Please pipe in! He has one.

Here is a thread:
https://www.6speedonline.com/forums/...ch-assist.html


John D's comments on this specific mod:
https://www.6speedonline.com/forums/1272569-post19.html



Jeff

 

Yup, that's it...

Check in group 7 #702 and you'll see it in the diagram... #1

https://techinfo.porsche.com/techinf...SA_KATALOG.pdf

Mike

 

Did some further testing; if I press the pedal down really slowly I have no scratchiness and pedal is perfect going in and out. If I press it down as I normally would a bit faster, the scratchy feel returns towards end of pedal travel… ???

 

I'm betting that it needs to be rebled first... Then if that doesn't cure it, you probably need a slave/accumilator.

Mike

 

Sounds like mine, had pedal assembly changed when I picked up car was ok but 3 weeks later now I got a squeak.
Mine was more off a notch last quater of pedal travel.

 

I just did a clutch and slave conversion from evoms at my shop. The results were great, get rid of all of those common failure components. Yes the clutch and the ps are part of the same system the both get pressure from the ps pump which is a tandem pump. Doing the conversion requires taking the ps pump out and taking it apart and pulling out the drive coupling to the second part of the pump that pumps the clutch cylinder unit and putting the ps pump back in the car. This is how you stop the pressure from going to the unit. As far as diag on the clutch feeling you have @ you foot. I would have to bring it in the shop and diag, hard to tell what it is without seeing the car first hand. If you don't want to replace everything in the clutch system before you find the problem you should get it diagnosed. I know you have allready tried maybe get a second opinion?

 

JCB,

As you mentioned, I have had the GT2 non-assist conversion for a couple of years / 20-30,000 miles of driving and I remain thrilled with it. I think the feel and feedback is perfect. It is considerably harder to depress than stock in a direct side by side comparison, but once you drive it for a while, it just feels normal and you forget how the OEM felt. If you drive an OEM after this, it feels terrible, IMO. You have absolute precision control of your clutch engagement with this set-up - every launch is totally predictable and directly/completely controlled by driver input...the slightest pedal movement, either in or out will provide a corresponding, predictable measured effect on clutch grab / engagement. Along with power and suspension upgrades, this transforms the car in such a positive way, it has to be of the best mods you can do. I can not say enough good things about it!

How's that for an endorsement?

 

Thanks John,

The parts are on my desk at home. Just waiting to find a day to do the drive to DAS in Philly....will report back.

I had a 1993 Audi S4. Now that was a clutch to push.... :-)


JB

 

How's that for an endorsement?

couldnt say it better myself.

 

I recently had a similar sounding issue. The dealer orginally thought the issue (they characterized as chatter) was due to "Clutch lines with unions attaching them," as Mike mentioned. Turned out though that my clutch was near end of life. If you're at 60k on the original clutch, you might be in the same situation.

 

I had the same problem and changed out my slave/acc, not the problem. Ended up being the needle bearings in the clutch fork/release bearing assembly were binding up.