Hi Guys,
Looking for a bit of advice (again) :-)
From time to time maybe once or two a month when accelerating hard in 2nd gear the engine rpm will suddenly jump from approx 3000rpm to almost red line but with no increase in speed. Just like the clutch is slipping or the tranny has jumped out of gear.
Backing off on the throttle sorts the issue out and everything is fine again.
My first thought is clutch, but I can't repeat the problem on demand and it never appears under WOT in the higher gears 4th, 5th and 6th where I would expect it to be most apparent if it were the clutch.
I thought it might be wheel spin, but no.
Any ideas suggestions ? How might I 'test' the clutch for wear / slippage ?

FYI the clutch has about 14500 miles on it and was re-surfaced about 7000 miles ago when a new engine was installed.

 

Is this happening immediately after a shift or will it happen if you have been driving in 2nd for a while and then getting on it?

 

can't seem to replicate it unless I've just shifted - which is why I'm not sure it's entirely clutch related.
It's almost like the clutch doesn't always fully engage after a shift until I back off the throttle for a moment.

 

Hot clteched (that have just been slipping) can get grabby and actually grab harder. Maybe that's the issue? The clutch gets hot and you can't duplicate it?

 

In the 99's and early 2000 996's, there was a problem with the clutch actuator lever which could cause this symptom. I have also see bad levers every now and then in many cars troughout the years. In trhe case of the 996, the lever would sometime **** a little on the shaft and get stuck for a few seconds while releaseing. This would not allow the pressure plate fingers to fully release from the disc and the clutch would slip. A newly designed lever was provided by Porsche. I would experience this at times during a maximum rpm shift (quick shift) from 2nd to 3rd. The disc would slip for about 3 seconds and then finally grab. Shifting slowly allowed the lever to complete it's travel without a problem. I replaced the lever and it was fixed.

However, you need to remove the trasmission to get to the lever, so you'll be able to look at the entire system.

 

The 996 and 996TT are not the same system. You will find that when the clutch gets hot at all from a little slipping from fast shifts or hole shots it will let go. Pretty common on the TTs. 14500 doesn't seem far off if you are aggressive with it. My first one latest a while then I made a slip during a track run and burned it. It was toast, pun intended.

 

I appreciate your comments and will keep a check on how it progresses.
I'm still a little puzzled though why the higher gears are unaffected as they are presumably handling more torque.
FYI I don't think I've been over agressive as I normally get it rolling in 1st before hitting wot in 2nd and only do that occaisionally, but none the less seems a new clutch could be in order before too long.
In which case I think I'll have it uprated in expectation of future mods - reflash and billet BOV's for starters :-)
Any suggestions for a more robust clutch assembly which is still streetable and a good shop in So Cal area (San Diego) ?
Cheers Tim

 

One way I've tested street car clutches in the past is to find an uphill section of road; it needs to be a pretty good incline, then put the car into a relatively high gear say 3rd or 4th from a low speed and then floor the throttle. If the revs run away and the car doesn't respond by accelerating it is most likely the clutch.

Of course another way is to smell the toasted clutch....;>0

 

Hi Garey,
yeah that's the way I've tested a clutch before - that and braking at the same time to load the clutch plate up with gobs of torque.
To date no indication of slip when driving like you mention, only transitory slip from time to time when shifting.
So maybe the clutch is in it's early stages of failing - I'll keep an eye (and nose) on it !