What's going on with my clutch?

[944Fripp]

My S2 has after 110,000 miles had a new clutch. However it has been in the garage for 3 weeks because the new clutch slipped! It's not a specialist but it is a reputable garage, the clutch and kit is OEM and the engine is completely standard. After a second new clutch it still slips. It occurs when you give it the beans and is most noticeable when changing down to 3rd at around 50-60mph. Revs hang at around 5,000rpm but acceleration does not occur for a good second or so. No slip is to be found lower down the rev range at all, it feels as torquey and responsive as ever.

Is there anything else that could cause these symptoms other than a worn/incorrectly fitted clutch?! Slave or master cylinder perhaps (although I've not noticed any fluid leaking the pedal has a tendency to sink when stationary for any length of time; this is not a new thing and the reason for it has never been found despite numerous attempts)) or maybe something in the transmition? S2's aren't fitted with an LSD are they as this my need looking at? Anybody got any insight?!Thanks in advance.

 

[Lowtimer]

The S2 can be, but usually isn't, fitted with an LSD. However, either way, the choice of open diff versus LSD would have no bearing on the symptoms you describe.
I think you are on the right track in suspecting the hydraulic actuation of the clutch, since there is good reason to believe that the clutch itself is OK.

 

[pauljmcnulty]

Pedal hitting the floor is most likely hydraulic. Slave cylinder, master cylinder or the joining pipe, in that order. Look for obvious leaks from the pipework, or fluid around the pedal. The slave won't show a leak as the fluid disappears.

 

[robwright]

I think it is unlikely that a failing cylinder would cause those symptons. Trust me I have had both of them fail. My money would be on looking at how the clutch was installed. It could well be that the clutch itself is a bit duff.

 

[tref]

Does it use any oil? Crankshaft oil seal? What was the old clutch changed for - the same problem?

 

[JamesO]

My money would be on contaminated/duff clutch.

Or the flywheel has worn at an angle like the one in my shed that needs to go to the tip, so a nice shiney new clutch wont have a large contact area and will slip.

 

[944Fripp]

Thanks for all the pointers. I just can't see it being the clutch due to the fact that it has had 2 new ones fitted, both brand new, in the last month and they both act the same way. The garage is a good place (I've taken my last 3 cars there), and I know that when I took it back the first time they were straight on the phone to Sachs and Porsche UK to double check if it could be fitted wrong (apparently it's pretty straight forward if you have the right tools).

I will double check the hydraulics anyway due to the dodgy behavior of the pedal as I'm sure that sorting it now (or next should I say, when I can afford to!!) would probably be a good move. Apart front the pedal itself, any pointers on where parts are located?

Are there other symptoms of a worn flywheel that are obvious?

One thing that would really help us car novices is if someone could stick a nice big, high res picture of these engines (particularly the 3.0l one) on this forum with everything major marked up on it for reference; it'd be a great starting point for most of us who want to take an interest in the working bits of the car but don't know what to look for. Any volunteers?! Or am I missing something? Is there already one on here?!

 

[944Fripp]

Oh, the last clutch was changed because it was slipping when cold, engaging a gear was becoming more and more difficult and the clutch release bearing was making a right old racket! It was definitely needed!

 

[Mike_Pollock]

Those symptoms are also possibly hydraulic related - I'd be double checking that.
1 Pedal should not "sink"
2 If not getting full "push" on clutch, it can drag leading to - a, drag - difficulty engaging gear and b, increased wear
Mike

 

[david924s]

If the clutch has been removed and replaced as you say then if there was any contamination it would show up on the plates, I would go with a hydraulic leak maybe the pipe from the clutch reservoir my S2 has had that replaced twice in its 100K life.

The other thing to look at I suppose could be worn trans mounts or it not being fitted correctly so the whole unit can move backwards moving the clutch off the flywheel, maybe when the car is moving at a pace and the rear wheels trying to pull everything back sounds daft but if like you say there are no leaks maybe worth a look when its on the ramp.

I had my clutch changed about 5 months ago for a Sachs unit as well as the gear linkages and it has been fine but my trans mounts and other connecting stuff was fairly new, plus it was a Porsche specialist, I know you trust the mechanic but maybe it is something Porsche specific, remember the program on the "Garage" they spent days trying to fix a 944 clutch and it turned out to be a bent clutch arm.

 

[AndrewS]

Hi,

For the clutch to slip, the friction plate either is slipping against the flywheel or pressure plate. This could be caused

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by any of the following:

:: Oil contamination from crankshaft rear main seal
:: Badly surfaced or uneven flywheel
:: Slave actuator unable to return fully after pedal depressed
:: Pedal movement being hindered (can not fully return)
:: Inadequate clamping pressure (pressure plate)
:: Master cylinder (hindering pedal return)

To eliminate the last one, pull up the drivers footwell carpets. If there are any issues with fluid coming back from the Master cyclinder, floor will be wet with fluid.

Visually check the other points. #1 or #3 are most likely (I think) based on your description of the symptoms. Hopefully its #3 and a simple fix.

Regards,
Andrew

 

[FistsOfHam]

Worth checking the slave cylinder. Mine had corroded on the inside and meant that the piston got stuck after I had bled the system. Could be a similar thing in yours holding the clutch slightly dis-engaged?

 

[peanut]

ORIGINAL: AndrewS

Hi,

For the clutch to slip, the friction plate either is slipping against the flywheel or pressure plate. This could be caused by any of the following:

:: Oil contamination from crankshaft rear main seal
:: Badly surfaced or uneven flywheel
:: Slave actuator unable to return fully after pedal depressed
:: Pedal movement being hindered (can not fully return)
:: Inadequate clamping pressure (pressure plate)
:: Master cylinder (hindering pedal return)


Regards,
Andrew

Excellent answer Andrew.
I'm surprised that it is only slipping in third and not in first and reverse where you have higher ratios.

I would ask ,when you boot it are the revs definitly increasing significantly ?
Only other thing I can think of as an outside possibility is that the wrong cover for the clutch plate has been used ?

If the clutch has definitly been slipping it should have shown on the surface of the last new plate fitted I should have thought.

Next thing I would check would be the first motion shaft to make sure the slines are not damaged and the plate moves freely on the splines for its full travel