Just had a really off-the-wall idea...

If you took the flex plate and made a few laser cuts to "soften" it up - that is, make it easier to dish in and out - would that reduce the chances of thrust bearing failure?

It would appear at first glance that if the plate could move more easily, the clamp might not move, and you might never have enough pressure on the bearing to cause failure.

Of course, then you have the question of how much radial or S cuts would lower the torque capacity of the plate, but my guess is that it would still be adequate.

That will give you guys that still have to commute something to think about as you creep along...

 

There's the 944 rubber flexplate.

 

Will it fit?

 

I don't know but I'll take a look later on and see.

Trying to run with your concept, though. More flex.

 

Is that really the problem? It seems to me that it is constant forward pressure causing the deflection, if it were push pull then would not some flexplates bow the other way?
I defer to your greater knowledge, but I needed to ask.

 

Wally,

After regards, on the TBF episodes I have seen here, the flex plate plastically deforms to the point where it would be useless for future use irrespective of the engine condition. If the spring steel leaves were to be slotted the forces generated by drive shaft extension would simply deform the flex plate earlier to the point where it is locked and was no longer springy. Whatever has caused the flex plate hub to slip will still continue and TBF is assured unless the leaves can completely fail sacrificially but then would it take the torque loading? Doubt it.

The only way to stop this along the lines you suggest might be to have some kind of frangible joint that fails at a safe level of horizontal thrust. It could even be designed to be mechanically reset but cost..? Such a construction might also require a revised torque tube design just to fit it in.

Not worth much more than 2cents I am afraid.

Regards

Fred

 

I'm thinking a softer flex plate will lead to more clamp creep, unless the plate is very soft.

 

Wouldn't 'softening' it up potentially cause a weakness in it? Not being able to handle the torque applied in transfer to the trans?

 

The idea is to soften the plate so that it doesn't apply enough pressure to cause the clamp to slip. If the softer flex plate could absorb the change in length of the driveshaft without putting appreciable pressure on the clamp - problem solved. If the clamp doesn't move, the flexplate doesn't run out of travel.

I'm willing to bet that the flexplate could be softened quite a bit and still hold the torque of the engine.

 

The problem is the factory single-split clamp, which doesn't clamp strongly enough all the way around the splined shaft.

Add a little more compression/friction, and the creep stops.

 

Agreed, but perhaps it would be better if the softer flexplate didn't push so hard on the thrust bearing in the first place. If it pushes so hard that the factory clamp slips, there has to be a lot of pressure on the bearing.

Keeping the clamp from slipping does nothing to reduce that pressure...

 

Wally,

I understand what you are saying. But instead of doing it that way, why no do like the manuals and just engineer a sleeve which can slide back and forth on the shaft not clamped at all?
That is what the manual cars do after all.

 

I've always wondered that. My Jeep and Suburban automatics and front drive units have splines that move and are not pinned. Why is our 928 different. Must be some reason. Wish I understood.

 

Wally, If you have a flex plate,I have a laser and would be willing to help you experiment any way you want.I love this stuff!! Ed

 

Yeah what he said