David L. Lutz

We had some discussion a week or so ago in this thread: https://rennlist.com/forums/showthre...ight=converter where both Jeremy's (porsche928guy) and my car had a new rebuilt torque tube, new converter housing bearings, and also had Edge Racing Converters increase our stall speed while the converter was out of the car.

I also replaced the seal in the tranny where the Torque Converter shaft inserts and also changed to the world famous Constantine Clamp.

After all was installed both cars had a terrible vibration increasing with RPM to the point of really bad above 4000 RPM.

Mrmerlin suggested " on the torque converter? this might cure things as usually the driveshaft/torque converter are did you refit the TT vibration damper between the rear bearing support and the center bearing support??
Did you try to turn the rear flex plate one space all balanced"

I confirmed with 928intl that the damper was installed ready to go at rebuild so moved on the the second suggestion.

Yesterday I rotated the rear flex plate 1/3 of a turn (or one space) where it bolts onto the converter. And WoW the vibration is almost gone. There is some left at about 4200 - 4500 RPM but passes fairly quickly. I could live with the car as is, but am now wondering if I should go another 1/3 of a turn and all might be back to normal. Please note that before the change there was no vibration at all!

Has anyone had this experience? Should I go to the trouble of moving it another 1/3 turn, risking only having to move it back! I sure don't want to push my luck and drop a bolt down into the converter housing while doing this.

One more issue. When I first started the engine I was getting some seepage of tranny fluid out of the converter. Some small drops of fluid not much at all. Now it has stopped. Is this at all normal for that seal after replacement? I thought maybe with the really bad vibration maybe it caused the seepage of fluid around the seal. I actually replaced the seal twice (screwing up the first one) so I am fairly sure it is installed correctly! (flush with the face, not pushed back to plug the drain back holes)

Comments welcome.

porsche928guy

David...sounds like some progress! I'm going to Europe for a couple of weeks so I won't be able to get to mine but as soon as I get back I know what I'd doing! I really hope this solves the problem for mine too! Thanks for posting your results!

Black Sea RD

Hi David,

Sounds like Mr. Merlin knows his stuff! Great that it worked for you and I'm wondering why the WSMs, IIRC, do not have anything about this as a precautionary statement with the placement of the torque converter.

Could the rest of the vibrations be other causes, like wheels, tires, trans/engine mounts?

Good luck and keep us posted,
Constantine

David L. Lutz

Constantine,

I too was wondering the same thing. I actually went back and read thru again making sure I didn't miss it, but found nothing.

The Trans. mounts are brand new and the engine mounts only 1 1/2 yrs. old. I do need an alignment and tire balance and I know some of what I am feeling now are my wheels etc. I replaced the tie rods, and one lower ball joint, had the compete rear end out and I know it needs aligned. I have had it on & off jack stands so much the past week i just havent driven it enough to get it settled and ready for the alignment. But I am doing it Monday.

Thanks for your input.

Bill Ball

The flexplates are balanced units, so I'm not sure why Stan's idea works.

David L. Lutz

Bill,

So what you are saying is that the front Flex plate and rear flex plate are balanced separate from Torque Tube as well as the converter? If this is correct it should not make a difference, but for some weird reason changing the rotation has made a difference. Actually I could live with it the way it is now (I think), but before there was no way!

But I really don't want to stop here, because I have that feeling something here is just not correct I am just wandering if anyone else has had this problem with the EDGE converters after changing the stall speed? Anyone?

Black Sea RD

David,

I put an EDGE converter into my former track car while it was still an auto. Other than a feeling the torque converter was hooking up better, no vibration issues at all.

In fact, during the whole TBF research phase I did a lot of TT R&Rs and never had this sort of problem come up. But there could always be that first time...

Cheers,
Constantine

atb

What's the turn around time at Edge? I may be sending my TC in.

Black Sea RD

IIRC about two weeks, one week for your's to get there and be inspected and if found okay, an EDGE converter sent back to you.

HTH,
Constantine

David L. Lutz

That's what it took for mine. Most of the time in shipping. Talk to Andre, he is very good to work with.

Mrmerlin

Dave add a bit of something sticky to the bolt socket and turn the flex plate one more hole see what happens. If it gets worse go back, if it stays the same then you migt try this same thing with the front flex plate.
I know its a lot of trial and error but you might just find perfection. All said and done , with the engine at TDC the drain plug for the torque converter should be lined up with the grate at the bottom of the trans. If its not linerd upi I dont think it matters much it will just a bit more difficult to find the plug

Mrmerlin

one more thing that i forgot to add to this discussion is the fact than not always do the clamping parts get oriented at 180 degrees apart this can also cause some imbalance IE the clamp bolt for the rear goes up and the clamp for the front goes down, trying be placed at 180 degrees apart this is actually easier to do when the whole driveline is on the floor

Bill Ball

The flexplates or carrier plates as they are called in the PET are only sold with the hub flange attached and you will notice scallops cut in one or two of the flexplate arms for balancing. There is no procedure for balancing the TT assembly in the WSM, nor is there any procedure that calls for removing the hub flange from the flexplate. So, I made the conclusion that the flexplate assemblies are sold as balanced units, although I can't find anything definitive that says that. That being said, had someone detached the hub and moved it relative to the arms, it could be unbalanced. If I have this all wrong, I sure would like to be corrected.

David L. Lutz

I didn't know the drain plug is suppose to line up at TDC even though in the past I have lined it up a couple of different times to drain the fluid just using trial and error to get it lined up. I will check to see where it is now.

After removing the 1st bolt I figured out that I needed something tacky in the socket so I used some automotive adhesive I had on the shelf and it worked great. Thanks for the tip.

I am taking it in for balance and alignment Monday and at some point next week I will rotate one more position and check it out.

Thanks all for the help

Bill Ball

Stan: This is a good one. Are you saying the factory installed the TT this way? Once the shaft is through the flexplate hub, you can't change this other than in 120 degree increments