[Beeza]

I've been investigating an annoying vibration that only occurs at 2500 to 2800 rpm. I originally thought it was the clutch input sliding tube, as I had to re-manufacture it after it had the allen bolt welded onto it! I thought it was out of balance, but it seems to balance statically.



I have dropped the transmission and withdrawn the torque shaft. The shaft is not bent and rolls evenly on a flat surface. I have noticed that there is no bearing from the mouth of the TT at the clutch end until more than halfway down the tube. Is that right? My thoughts are now that maybe the shaft doesn't have enough support within the shaft which causes it to whip and vibrate. Maybe the forward bearing has migrated aftwards.



I haven't dropped the tube yet. I'm a bit reluctant to drop the rear suspension just yet.

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[flash]

i am hoping that you are not tracking down the same thing i was, which turned out to be an unresolvable issue related to an aftermarket single mass flywheel - it happens with all of them, some more than others, but it is not curable



as for the TT, as i remember, there are 2 bearings - they require a long ram press to R&R them

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[Beeza]

I still have the original DMF. Would you happen to know roughly the length form each end the bearings are? It seems strange that there are only two bearings. I've read in Clarks garage that there are four on the 944 and three on the 944 S2, but only two on the 968?

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[flash]

sorry - no clue - i paid to have it done

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[banditsc]

You could email this guy, he rebuilds the torque tubes for our cars. constantine@blackseard.com

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[Eric_Oz_S2]

There are 4 on the S2. I have the dimensions from the front somewhere if you need them, but not much use if the 968 only has 2. The ones in the S2 are fairly close to the front and back. Does the 968TT have a slit in the front like the S2. The first bearing in the S2 is only around 100-200 mm back from the rear of the slit.



Eric

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[Beeza]

Hi Eric,



Yes it has a slit from the front down to about two thirds of the way down. There is no bearing anywhere along this slit. I'm sure it must be my problem.

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[Beeza]

Well it's finally fixed.



After the recommendation, I contacted Constantine at Black Sea R&D. Initially by email and then on the phone. What an amenable guy! He concurred that my problem was caused by the migration of the forward bearing down the torque tube caused by the slit that Porsche put in the 968 TT to try and dampen driveline vibrations.



He agreed that the easiest solution was to leave the migrated bearing where it is and simply put in a new one at the front end. He sold me a reconditioned bearing unit which I was able to fit with the TT in situ. I didn't really fancy the idea of dropping the rear suspension. About an hour of slugging at it with a two pound lump hammer got it into it's final resting place!



Constantine then suggested that I should try and close some of the gap made by the split by using a couple of 3 and a half inch exhaust clamps. That should stop it moving again. He also sent me a picture of a much more elegant solution that involved welding some tubing either side of the slit then tightening down with long bolts and nuts. Easy to do if you have the torque tube on a bench, but I elected for the exhaust clamp method.



It's now back together and the car is transformed. All traces of vibration have gone. All in cost was $80, but a lot of work by myself. Phew!

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[tamathumper]

Nicely done!

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[Eric_Oz_S2]

That is impressive installing the bearing insitu! On the s2 the exhaust hanger clamp does the job of keeping the bearing carriers in location. However i also added some rivets through the tt behind the carrier to act as a stop.

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