Black Sea RD

Like I said, I understand the damage that can be done by a poorly installed rear pinch bolt.

However, if the drive shaft can move at the rear then there will not be a forward bow at the front flex plate. Any pressure would be taken up with the slip at the rear coupler.

It is when the drive shaft is pinned down but not enough for it to be pulled out a bit under load at the front clamp. Then it hangs up and starts the forward bowing since the drive shaft does not have enough force to force itself back through the front clamp and it's clamped at the rear. The pressure is taken up by the front flex plate bowing toward the engine.

I also have to disagree about getting the lube out of the clamp and drive shaft connection. Brake clean will do a great job on the light spray type lube we are talking about like WD-40. One just needs to make sure to penetrate into the clamp and drive shaft area well.

You can also move the front flexplate off the drive shaft splines by disconnecting it from the flywheel, like I suggested earlier. Then you can really go to town and clean everything up. No need to drop the torque tube.

As far as the Super Clamp, it is far superior to any rendition, if I do say so myself.

Mrmerlin

just curious where the damage is on the driveshafts rear splined area you have at your shop,
to to forward area of the splines or to the rear..

You said,
However, if the drive shaft can move at the rear then there will not be a forward bow at the front flex plate. Any pressure would be taken up with the slip at the rear coupler.

I dont agree with this as the TT bearings will hold the driveshaft in a position that will add a preload to the flex plate since the rear bolt is loose the shaft will stretch and the bearings can hold it in this position as well as the poor clamping ability of the front clamp to clamp securely, this causes the flexplate to move on the splines

Note the driveshaft twisting longer and shorter as torque is applied takes a while to manifest and the weakest links begin to show , SO if the rear of the shaft is secured so its movement is reduced or eliminated then the front will flex via the plate and more or less be held constant, as there isnt any way the shaft can migrate forward more than the original design allowed, thats if the rear bolt is tight and holding as it was designed.

This can be seen where the flexplate is checked and both front and rear bolts are retorqued to 66ft/lbs then driveshaft migration/ flexplate migration is reduced or eliminated.


Checking the rear pinch bolt shouldnt even be a question it should be part of the procedure,
virtually every 928 I have checked has a rear pinch bolt thats not as tight as it should be.

Note this also ,includes the 5 speed versions

If thats not enough information for you I really dont know what else to say,
but only these are my experiences and I am paying attention to what I see.
Once the bolts are done to the 66ft/lb and blue loctite is used ,
then upon rechecking, the bolts have been tight tight as they were when I originally set them.

I hope that you also recommend that the rear pinch bolt be checked when installing/ checking any TT issues or flex plate checks/ crank end play checks

Black Sea RD

Stan aka Mr. Merlin,

The damage we've seen is mainly due to the rear bolt being forced through when the groove was not properly lined up with the rear coupler cut out. The few others were at the rear of the drive shaft due to the transmission being forced on or off the splines or when the pinch bolt was not removed (!) before trying to remove the transmission.

Just read your revised comments about the drive shaft migration from the rear and I can't agree with them. We studied this whole problem for a few years and what you are suggesting was never a part of the problem or a problem itself.

For starters, the TT bearings cannot hold onto the drive shaft in a loaded state.

Before this gets to be a long winded back and forth, I'll bow out now.

With respect,

Mrmerlin

Still Constantine, I hope that you also recommend that the rear pinch bolt be checked when installing/ checking any TT issues or flex plate checks/ crank end play checks

Black Sea RD

Yes!

To do otherwise would not be conducting a thorough review of the driveline.

Regards,

the flyin' scotsman

Alls well that ends well someone once said.

Shes all buttoned up, clamps torqued, inspection cover on, wheels down and rolling.

Constantine....we'll chat off line.

thx all again....I'll close this one off