Cosmo Kramer

Had the exhaust off and thought I would check the flex plate. Put my straight edge on it and it was definitely bowed. Loosened the bolt and clamp slid back 5 - 6 mm! I am borrowing a dial indicator tonight to check the play but it seems very minimal.

Pklamp is on its way now and gonna be checking this regularly.

dprantl

Man, you should have done that *before* the supercharger installation! If a stock 928 can get TBF, I would imagine one that is making 50% more power would get it x10 faster. I wonder if the PKlamp is strong enough for forced-induced 928's, or if Constantine's clamp is the only solution that will work? Not much testing done in this area that I've heard.

Dan
'91 928GT S/C 475hp/460lb.ft

Glenn M

I'm going with Constantine's clamp on my NA 88 and soon to be TS SC'd 87. Not worth the chance in my book.

Cosmo Kramer

Bill Ball ran with the stock clamp for years on his S/C S4, he just released the clamp every 3 months. He has installed the Pklamp and has had 0 movement in 3 months or 7000 miles. With the stock clamp he was getting 1 - 3 mm in the same time frame.

https://rennlist.com/forums/928-foru...ghlight=pklamp

Thank god I only ran it a couple of times with the S/C!

Mrmerlin

dont forget to check the rear clamp bolt its probably loose fit this bolt first before tightening the front bolt use blue loctite 66ft/lb

Cosmo Kramer

Was planning on it thanks Merlin. I will be sure to loctite it as well.

Does anyone know if you loctite the bolt on the front clamp and the Pklamp as well?

Mrmerlin

loctite them all use the blue its easier to remove

the flyin' scotsman

Ken recommends the use of loctite:

http://liftbars.com/docs/PKlamp.pdf

gearz

PKlamp instructions say loctite blue on the PKlamp bolts. No loctite on the factory clamp bolt.

Installed mine last week.

Imo000

Ted, You can borrow my dial indicator if you want to.

Cosmo Kramer

Thanks for the offer Imre, but I already picked it up on the way home from work.

Well I am in good shape, my end play is only .0065", spec is .004 - .012".

As a side note, I read lots of threads here on the procedure to check this with a dial indicator. The pics showed the plunger for the dial indicator on either the flex plate or the flange bolted to the flex plate. I could only get accurate results by putting the plunger directly on the flywheel. I think even with the clamp bolt loosened off completely that the factory clamp can stick in the splines enough to bend the flex plate just enough to throw the reading. Off the flange I got .002 which I knew was incorrect.

I pried back and forth 6 times, each pry they was a distinctive thump of the bearing bottoming out, and the gauge went back and forth perfectly from 0 to 6.5 each time. I had the plunger pointed on the flywheel at the closest point to center.

FredR

Ted,

If it jumped 6mm then you are very fortunate indeed. Many examples seem to jump about 3mm and not suffer any problems.

Maybe the list admin can send an auto message to all new members cautioning them of this potential problem on automatics when they sign up but then I guess the legal implications have to be considered.

As a matter of interest [and not to brow beat in you in any way], noting that you have been on the list for a year has the potential problem of TBF just come to your attention or did you not understand the potential implications? The subject matter comes up regularly enough so I am little puzzled as to how this might have escaped your attention and it sure as heck should scare any owner as TBF leaves you with little more than a large garden ornament that resembles a 928. At current prices a 928 with TBF failure must have little residual value.

At least you caught it and that is great news.

Regards

Fred R

Cosmo Kramer

No worries Fred I am a big boy....

I bought the car last winter but at the time of purchase I didn't know the issue existed. I did learn about it after a few months on this board. I haven't put too many miles on the car under my ownership, so any damage would have already been done.

With the knowledge I have gained here, this would definitely be on a PPI before I would buy an automatic. It is strange how it works and every car seems to be different. Upon inspection, it was obvious that my clamp had never been touched since it left the factory and currently has 100000 miles on it. There was definitely forward pressure on the thrust bearing but the play was still on the tight side of spec. You will read other posts of cars with less miles and the thrust bearing is completely gone. There doesn't seem to be any pattern to it at all.

ew928

May indicate how the car was driven by the PO('s).
Wonder if how hard and often the loud pedal was mashed in fury and if on uneven road surface where the torque tube gets rapid load and unloaded affects TT creep.

LSD transmission or slippery diff so 1 wheel spins to ease the transition to full traction?

Cosmo Kramer

My car was a one owner and didn't look like the kind of guy that goes drag racing. Previous maintenance left a bit to be desired but the car is pretty good overall. Most of them do have skeletons in the closet! No LSD.