Mongo

Okay last night Bill and I decided to check the play on the flex plate to make sure there isn't too much stress on the thrust bearing.

We measured aproximately a 4mm bow on the flex plate prior to loosening the pinch bolt. Boy that sucker pop back pretty far afterward! My flex plate now has about a 1mm bend in it though, but pressure is released.

Now my next question, I put loctite blue on the pinch bolt and torqued to 66 ft/lbs. Should I have put loctite on the torque tube splines before tightening up that collar?

How often should I check this puppy for movement?

WICruiser

I didn't put loctite on mine and plan to check it about once every year or so until I get a history ('85 - auto). I don't think mine was ever released before but I have no records from POs.

GUMBALL

What you did was correct, blue is easily removable.

the flyin' scotsman

I didn't Loctite my pinch bolt and it was good from '05 release to '06 check. Yet to check this year but with our anual check I don't anticipate concern.

SharkSkin

Agree, loctite will give you nothing but grief later.

ROG100

I Loctite all my splines with penetrating formula as I do not want it to move ever again.
Each to their own.
Non have moved period.
Just my 5c
Roger

Mongo

Penetrating formula...is that like a green thread locker? I saw one made by permatex.

Schocki

Loctite 290 is the stuff to use, it is thinner than water and is designed to secure assembled thread connections. I Loctite my spline in the GTS 2 years ago, no movement.

Black Sea RD

I guess the default to use loctite in the front flexplate clamp is due to cost and simplicity.

IOHO, loctite should never be used in the spline area of the front flexplate since it makes it extremely difficult to remove the driveshaft later or reposition it if it still moves as it did for at least one person in the past. If you say so what, you will understand when you need to remove the TT in the future or when the new owner (maybe someone on this list?) needs to do so.

The tests we conducted has also shown front flexplate movement to occur within a few hundred miles of re-positioning the driveshaft, depending on driving style and how stretched out the front flexplate clamp is. The more one un-clamps and re-clamps the front flexplate clamp causes it to lose some of its clamping force over time due to its design. Our tests have also shown the use of a new pinch bolt clamped to a higher torque rating has no effect on stopping the driveshaft movement.

HTH,
Constantine

ROG100

Constantine,
This is in no way a distraction away from your device to lock the flex plate and you should be applauded for its design.
However it is relatively expensive in my book, particularly when we have another more cost effective solution available. Loctite 290 is not cheap either.
I have used 290 on a number of cars and I also have a concern that it could be hard to remove at a later date.
After talking to Loctite in the early days they allayed my concerns.
They clearly state that if 350F of heat is applied to the spline then the joint will come apart easily.
So I have a solution if the need ever arrises. Not proven yet though.
Roger

Black Sea RD

Hi Roger,

No applause needed, just trying to give to the 928 community to keep these beautiful cars on the road for awhile longer. And no offense taken at all, I think these discussions help to raise the awareness level of this whole problem and ultimately the decision is the 928 owners on which way they want to go.

As far as our clamp being expensive, $380.00 is not that bad, especially for what you get. The clamp fits all 928 automatics, stops the driveshaft pullout, can be re-clamped indefinetly without any loss of clamping force and will probably outlast the car. If you were able to install one and use it you would see it is an elegant solution to this problem.

Heating the loctite to that temperature in the splined area of the front flexplate clamp will take a lot of heat and time since the heat will be drawn away from the loctite by the surrounding metal of the flexplate, clamp, driveshfat etc. Others have tried heat with no effect and had to resort to other methods to remove the TT from the car. Let alone to re-position the front flexplate in case it does move for some reason.

As far as another solution, 928 Intl. has taken a portion of our research, which found that the bearing, circlip, and washers initially used by Porsche to set the pre-load between the front flexplate and flywheel also aided in stopping the driveshaft from being pulled out, and have started offering these parts again. These parts can only be used with the older longer style driveshafts which 928 Intl. offers in their rebuilt TTs.

The reason we didn't go with this approach is that this does not help owners with the newer shorter driveshafts and the parts are not that easy to install properly. Porsche stopped using these parts for a reason and from what was gathered from our investigation, Porsche field techs seemed to be having a problem installing these parts correctly which caused some instances of TBF to befall customer cars. This would explain Porsche's abrupt stop of using these parts. IOHO they should have re-designed the front flexplate clamp to a better clamp when they stopped using these parts. That's why we designed what we did.

Have a great day,
Constantine

Mongo

Constantine, what is your method of securing the driveshaft to prevent movement?

Black Sea RD

Hi Andy,

We devised a new clamp, a picture of which can be found using the search feature for this forum, if you haven't done so already. It replaces the OE clamp on the front flexplates and as I said earlier can be used in all model year 928 automatics.

Cheers,
Constantine

ROG100

Constantine,
You make a very compeling argument and maybe I need to relook at your solution.
As you say $300+ is a small price to pay for peace of mind.
Roger

Black Sea RD

Hi Roger,

Just let me know, I still have a few available. If your into 928s as I can see you are, you will really like this piece.

Kind regards,
Constantine