[jaap]

Hi,



I think I need to replace my clutch but would first like to have a look to see if something obvious is wrong. Clutch is sticking (does not immediately release) and I already replaced all hydraulics. Can you remove the clutch housing cover (service panel?, not the small rubber cap) without removing the exhaust?



Jaap

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[flash]

how is it sticking? is it just the pedal? if so, i'd check the pedal adjustment and return spring first - it needs to be in a particular position to work correctly



also, did it get fully bled? - these things are a pain to bleed, frequently requiring not only the power bleeder, but also the traditional "push-open-hold-close-release" method with a second person - mine did



as for the cover, i know i cannot remove the cover on mine without dropping the exhaust, but i have a header - perhaps the stock manifold is out of the way enough, but i didn't get a chance to see that

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[prj24149]

I don't think so. I have the stock header and it is in the way. I read recently in the service manual and on the PCA website tech section that you have to drop the trans to remove the bell housing. Big job.

Did you measure the wear limit on the clutch through the inspection hole? Measure the distance from the left edge of the inspection hole to the top of the release fork, where the push rod from the slave cylinder pushes the fork. Wear limit is 35mm. New clutch is 18mm.

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[968norway]

Had a similar problem, clutch wouldn't disengage when it got cold. Found out that the splines were all gummed up with degraded grease, caused things to hang up. My mechanic cleaned and lubricated it, works fine now, no matter how cold.



And yes the cover plate comes off easily if you have a standard exhaust, at least it did on my car. I think he used a couple of hours to do the job, had to take out the clutch apparently.

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[jaap]

The clutch problem is similar to what 968norway describes although it does not depend on outside temperature. When starting the car when it has been standing for a few hours the clutch does not release immediately when depressing the pedal. For instance when driving in third and braking on the engine, when I depress the clutch the connection between engine gearbox remains for a few seconds. When everything warms up clutch operation returns to normal. I have bleed the system using both methods mentioned by flash and replaced all components and bleed again (several times). I think the clutch plate is not completely worn (about 26 mm in inspection hole). I also experience some cluth grabbing/judder when driving of in first, so could be te clutch plate not moving freely over the splines until it expands from heat? I assume that when I have to open things up to inspect this I can just as well replace the clutch components? (think it is still the original one with 180k km)



Jaap

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[SILVY968]

Jaap,



"cluth grabbing/judder when driving of in first" could be what I have. The problem is the DMF is no good. If it feels like you are a bad stick driver in first, especially when going up a hill, it may be the DMF.

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[968norway]

Another thing we changed was the operating shaft for the clutch release lever, it had some deep scoring on it. After this the clutch operation is much smoother. The car has 170 000 km on it, not sure about the age of the clutch, though it apparently still has some life left in it.

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[jaap]

Brian,



I also thought of the DMF regarding the grabbing so will have a look at it as well. I read somewhere there is a test to see if it is bad, will do a search on that.



Jaap

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[jaap]

Finally got time to inspect the clutch and because I already bought all the parts replace using Eric_K's very good DIY info. I was surprised about the condition of all the components; everything very clean, no oil no rust. The clutch disk had plenty of life left and flywheel surface was undamaged. I think the main reason for the sticky clutch was the lack of lubrication on the splined drive shaft (similar to what 968Norway described).



However there was a lot of play in the flywheel so decided to replace as well with a new flywheel I bought through eBay 2 years ago (100 euro). All bolts could be easily removed again following Eric_k's recommendation for removing one flywheel bolt at a time and a very good quality socket. Installation was also straightforward where the only tricky part was installing the release bearing into the pressure plate which took some effort (used both spacers but verified the bearing could still be moved as described by the clarks garage clutch DIY) Also replaced bearings in release fork and new guide sleeve. The shaft for the release fork was undamaged so this part was reused (removal could be done by just pulling it out without a hammer). Took about 4 hours from start to finish.



With everything back together there is no more sticking clutch and also the grabbing / juddering has gone. It even smoothed out the vibration I had in the gear lever (probably the result of the new DMF). However the only thing I am a bit worried about is a heavier clutch pedal. I would have expected it to be at least as light as the old one? The pedal action is smooth but requires more effort than before. Anything I could have done wrong?



Jaap

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[flash]

did you change pressure plates? on the last clutch order here, the oem rating of the pressure plate had been superceeded by a heavier rating, which gave a heavier feel

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[bob blackwell]

Jaap you may need to adjust the counterbalaance spring above the clutch pedal to obtain a better feel, it is awkward to get to but not difficult once you are upside down under the dash! Good luck, Bob Blackwell.

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[flash]

there is a spec in the workshop manual that specifies exactly how to adjust it and how much

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[jaap]

[quote name='flash' post='33638' date='Apr 3 2007, 03:16 PM']did you change pressure plates? on the last clutch order here, the oem rating of the pressure plate had been superceeded by a heavier rating, which gave a heavier feel[/quote]



Flash,



Yes pressure plate was also changed. However I don't know how 'old' the clutch kit was (bought on Ebay). The only thing I was not sure of during installation of the relaese bearing into the pressure plate was how many spacers to use. It took some effort to get the bearing clip in with two spacers installed but after that I could still move the bearing from side to side (not in/out) like I think it should to make it center correctly on the guide sleeve. The old release bearing also had two and most pictures of clutch insatllations I looked at also show two.



Bob, Flash,



I think the spring is adjusted according to spec, but may try to adjust it some more to help reduce the required pedal pressure.





Anything else I should verify? I think only a few things influence the required pedal pressure

Friction of release bearing on guide sleeve.

Release fork bearings and shaft

Possibly the number of spacers installed on release bearing.

Strength of pressure plate

?



Jaap

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[flash]

i'm guessing you got one of the pressure plates with the heavier rating (3200 vs 2500 or something like that) - i think they have been phasing out the light one for a while now - it's happening with other parts for the car too



you can check the potential release fork issues by disconnecting the slave - that will free the fork a bit - if it wiggles freely (though there won't be much), you probably have no problem there



the good news is that your shifts will be crisper

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[jaap]

[quote name='flash' post='33646' date='Apr 3 2007, 04:21 PM']i'm guessing you got one of the pressure plates with the heavier rating (3200 vs 2500 or something like that) - i think they have been phasing out the light one for a while now - it's happening with other parts for the car too[/quote]



Flash,



Just to verify, you mean that for the standard sachs clutch kit (not the sport kit as sold by paragon) they have increased the clamping force? Is there a way to identify the newer heavier pressure plate from the lighter ones? I confirmed all the numbers on the parts to be correct for the standard sachs clutch kit. Or do they now only sell the sport pressure plate as part of the standard kit or is the sport pressure plate even heavier (paragon mentions this to be 3200-ish)



Jaap

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[flash]

that is exactly what i am saying - we ordered a standard plate - we checked the numbers on both tthe box and the part itself - it was the 3200lb model according to the sachs part number on the part, but the porsche part number on the box said stock for the 968



i think it came from world pac

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[jaap]

Over the weekend I verified the lenght of the rod and spring. The spring was slightly off (to long) so adjusted this, but did not make a big difference on the stiff pedal feeling. I even tried to compress the spring some more but again this did not result in a much lighter clutch. Also bleed the hydraulics again just to be save but no improvement either. One thing I do notice is that the engagement point for the new clutch is much lower (closer to the floor) than with the old one. I would assume a hydraulic system would compensate for this?

it was the 3200lb model according to the sachs part number on the part

Flash, were did you compare sachs numbers?



My clutch kit did not come with any porsche numbers but I verified the sachs numbers on the parts match the ones on the box and sachs website. The pressure plate has the correct number for a standard clutch kit and is different from the sachs number for a heavy duty (=sport?) pressure plate.



I also learned from sachs (through email) that the pressure plate I have superseeds two earlier versions and has a slightly higher clamping force. May be this combined with the fact that the old clutch must have lost some of it clamping force after 15 years results in a big difference between the new and old however it does not feel as nice to drive now <img src="/forum/images/smilies/968/sad.gif" class="smilie" alt="" />



Jaap

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[flash]

i think i did it through sunset - i can't really remember the process, but do remember the results - at the time, there were a few phones calls bouncing around trying to sort it out, and i'm not sure which one finally produced the answer



it does seem to verify what our experience was though



drive it for a bit - you may find you actually like the stiffer plate - it will grab quicker and more firmly - however, it will be a bit more effort in traffic



for me, it's great, buecause this car is strictly a toy, and i have other cars for daily use - for daily use, it may be too much



the only thing i can think of is to loosen the spring tension a bit - i've never done that though, and have no idea how well it will work

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[jaap]

So, after more than two years hoping I would get used to the heavy clutch or it might sort itself out I decided it spoiled the driving experience to much. Especially with a new DD which has a really light clutch operation making the difference even more obvious. Its not only the additional effort required but also the fact that the clutch releases close to the floor so in traffic you have to keep applying a lot of force.

Because the original clutch assembly did not show any obvious damage when removed (clutch was most likely sticking due to lack of grease) I decided to take a gamble and reinstall the old pressure plate and see what happens. Everything still looked like new and job was finished in about two and a half hours

What a difference, the car is so nice to drive again with a smooth and light feel to the clutch operation. Should have done it much earlier.

Jaap

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[Johannvb]

Good to hear! I can't believe you got youself to work on your car in this weather!

Are you going to the "Anti Kerstverveling" tomorrow at Zandvoort?

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