lonnie77

I did. What am I doing wrong? 66 ft/lb on main bolt and 18 ft/lb on PK clamp.

before
https://www.flickr.com/photos/lonnie...n/photostream/

after
https://www.flickr.com/photos/lonnie...n/photostream/

ROG100

Lonnie,
I do not think you are doing anything wrong. The PKlamp goes a long way to alleviating the movement but over time movement can happen. Depends on miles and time driven between checks. Normal to see 3mm over a few months and a few thousands of miles without the PKlamp.

If you want to stop it permanently use the Constantine Super Clamp or Ritech Clamp.

FredR

Lonnie,

First thing you should do when you reset is paint the thread limit white so that you can see if it has moved forward without undoing anything.

You ask a fair question in that as Roger says they typically move 3mm if no secondary mechanism apnplied and further when you are TBF'd- however i have never read of one moving with the PKlamp fitted- has anyone else?

In your situation I would like to know why it has slipped. Torque wrench calibration correct?

I have used the Loctite method since 1999 and it has served me well.

Regards

Fred

Bertrand Daoust

Like Roger said, how many miles since last check please?
And how do you drive it?

Mine didn't move since the installation - about five years ago.
Don't drive it much. 5k per year.
Don't drive it hard either. Well not often!

ROG100

I have seen movement in rare extreme examples when the car has been driven hard over a high mileage (20k+). However movement was only about 1mm.

PorKen

(Filling in for Stan. )

Have you checked the rear pinch bolt?

Hilton

Also, don't just check the flex plate deflection - check your crank end play measurement (i.e. measure the thrust bearing wear).

OTR18WHEELER

Are your before and after PICS correct?
Usually the migration of the flex plate clamp toward the engine shows more of the splines if the rear pinch bolt is located properly. Your pic indicate that the shaft has migrated forward, or the clamp rearward.
In other words, if the rear pinch bolt and clamp are correct, your B &A pics indicate the flex plate has moved rearward, while the shaft remained stationary.

Mrmerlin

thanks Ken.

OTR is also very observant

lonnie77

Thanks for the response. The last time I checked was about a year ago and it had moved about the same. I haven't driven it that much but when I do drive it I like to have fun. The bolts were very tight so that is why I asked if I am doing something wrong. The rear pinch bolt, are you referring to the bolt at the transmission? This time I checked my torque with a second (new) torque wrench and it was the same.
What would be wrong if I leave the bolt loose and allow the shaft to slide?

FredR

Forget any ideas about leaving bolts undone.

I think most of us on this list who have been involved in this issue believe that the rear clamp does not slip if it is installed correctly which apparently is often not the case so first step is to ensure it is installed correctly at the rear end.

Back in the days [1999] when my front clamp was slipping it would do so in a matter of days and it always slipped by the same margin of about 3mm. Not only that I could also tell when it had slipped because I felt a strange drive line vibration at exactly 3050 rpm or roughly 90 mph that I liked to cruise at.

As to whether your clamp is aligned at the position where it should be is a moot point- I felt it was a little bit further along the splines than mine sits but to my mind that does not constitute an issue. The fact that it seemingly can move with the added support of a PKlamp should be the concern I would politely suggest. The only thing I can think of to explain this given correct torque has been eliminated would be if the splines have fretted to the point where there is simply not enough contact patch to provide sufficient overall total grip.

As I am concerned it is this apparent degradation that opens up the system to this appalling vulnerability and this type of movement that is the precursor to the "Full Monty" of TBF. The PKlamp is a very clever band aid but clearly it too has its limitations if the underlying problem is too far gone and the incremental grip it provides is just not enough to make up the deficit. As I said in my first post, I have never read of this happening before but logic suggests there will be a first time for everything.

Whatever the cause of your problem "the yellow warning lights are flashing brightly". I would hazard a guess and suggest that the PKlamp has already saved your motor so do not think badly of this gizmo that has probably paid for itself many times over already.

In your situation I would not run this motor until I had removed the current clamp and replaced it with a Constantine clamp and as Roger has stated there is also the Ritech solution to consider.

You might also consider the Loctite solution that I have used for some 16 years- that with the PKlamp on top of it it may suffice providing you apply the PKlamp immediately after the main pinch bolt is tightened whilst the Loctite is still green. To be clear I am not talking about using Loctite on the pinch bolt- the right formula [290] has to be applied to the splines after everything has been thoroughly degreased. After application the pinch bolt is immediately torqued, plonk the PKlamp on top for good measure and then leave the assembly to set for 24 hours without applying any load whatsoever. You then mark the shaft with white paint and use this as a tell tell to check if there has been any further migration, initially at regular but ever increasing intervals [ a few days. 1 week, 2 weeks, a month etc until you are satisfied the problem is solved.

If this does not work you throw in the towel and go for another solution at that point. To be clear I use the Loctite solution because at he time it was the only solution open to me and it worked. if I were to have my transmission system out for any reason i would probably go straight to the Constantine clamp- this is the solution Porsche should have engineered originally rather than the stock clamp that seemingly has caused and continues to cause so much distress to so many 928 owners.

Had it not been for Rennlist I would probably have been another one- makes the membership fee look cheap by comparison


Regards

Fred