Captain_Slow

I have a few questions, but first the numbers:

Drive shaft splines exposed:
Before = 5.36 mm
After = 3.1 mm
Difference (amount of flex plate deflection) = 2.26 mm

Crank end play measurements:
I repeated the measurement 6 times, each time prying the flywheel forward/aft and got a range of 0.20 to 0.23 mm. (WSM spec: 0.11 - 0.31 mm.)

A few questions:
1. It seems if the same amount of deflection returned, that after release the remaining driveshaft splines would disappear. No?

2. I noticed the effort to loosen the clamp was much easier than I expected, even using an 11 inch breaker bar. However, tightening the bolt to 65 lbs-ft with a 20 inch torque wrench required the effort I expected. Anyone have similar experience with the bolt loosening easily? Is this typical?

I'll order a PKlamp soon, but first I will drive it lightly for about a month to evaluate if flex plate deflection returns even when trying to avoid loading up the shaft with a lot of torque.

I also measured a distance from the lip of the bell housing to the TT bearing of approximately 10.5 inches. The end of the tape measure returned with a good bit of orangish grease on it. Snapped a picture down the tube and the bearing looked well greased and very clean (not saying a picture reveals much, but the bearing looked like new with a bit of fresh grease).

This task was something I needed to do before considering other tasks (new OPG, new motor mounts, intake and cam cover refresh, etc.). Held my breath a bit doing the math on the end play

Adamant1971

Go with a super clamp. I had a pklamp on my S3 and still had to release the pressure. I don't think the pklamp did anything at all, much more force is needed on the shaft.

My 2 cents

Avar928

The bolt was easy to break and loosen when I checked mine. You should be good. I was a bit more careful going slow on tightening since I didn't want to strip it by accident. I did, however, mess up one of the PKlamp screws but there's enough there that it'll loosen. Be careful on that. My mistake was I hit it at an angle and didn't have the bolt face completely towards me so that the hex bit wasn't fully seated.

Bertrand Daoust

Jon,

1) If the deflection return - it will eventually if you keep the stock system - the clamp will move backward again. So, you will see more splines again.

2 to 3 mm movement is normal.

You can put a little bit of white paint on the splines. Easier to check if there's any movement next time you remove your cover.
Don't forget not to put the 2 bolts on the back of the cover unless you will have to drop the exhaust system again!

Constantine clamp is the ultimate system but you need to drop the TT to install it. The PKlamp can be install without touching anything.
I have the PKlamp and it's working perfectly for me. No movement at all since the installation. I don't drive my car mutch though.

2) Mine was quite hard to remove the first time I did it. Maybe your's has been removed before and reinstalled without blue Loctite. ?
You should use blue Loctite on that bolt every time you reinstall it.

Also, it is a very good thing to check and re-torque the bolt on the clamp at the the back of the torque tube.

Captain_Slow

Avar928 -
How's the PKlamp holding for you?

Bertrand -
I think I saw your car (and took a lot of pictures of it) at Frenzy (yes?). Beautiful...I think right next to George's coral red...both were as new to my eyes.

I forgot to pry the flywheel to the rear before torquing the clamp bolt this morning, so I'll go get some white paint and blue Loctite. I didn't remove the bolt, just backed it off enough to loosen the clamp. The flex plate returned to neutral flat position.

I also had the thought that the ease of breaking the bolt free was due to the PO loosening it (one time). Interestingly, he said the flex plate didn't move at all when he released it. I'm wondering if the deflection I observed was due to the clamp not being either torqued to spec or just a case of it backing off because once loosened it becomes a "never holds the same again" kind of thing.

I don't drive mine much either, perhaps less than 2500 miles a year (mostly in the spring and summer). Will be interesting to watch this for awhile.

From your confirmation and previous threads I was glad my deflection was in the normal range. I'm curious to see if the deflection returns gradually, or with just several weeks of light driving.

Does the rear bolt pass through an indent on the drive shaft? Seems this would prevent it from moving except in unusual circumstances. However, like you, Stan often reminds folks to check the rear bolt....and I will. Just curious if the there are differences at the back end.

Thanks

Avar928

I haven't checked since first installation in October. I only had about .11mm for crank end play measurement. I'll be checking it at the end of the month for 6mos evaluation though. I'll post here with results.

UpFixenDerPorsche

ARRRRRRRRRRRGGGGGGGGGGGGHHHHH !!!

The problem IS NOT movement of the collar on the front splines.

It is movement on the rear splines.

Where is the evidence of siding movement on the front splines? Eg would there not be even the slightest trace of scuffing / sliding given that the two surfaces are under compression?

Look at the rear central shaft splines/collar. Save yourself time and have a new collar bolt ready.

I went thru this this on my S4. Nothing made sense until looked at the rear clamp.

HTH
.

Captain_Slow

UFDP/HTH -
That's where I'm going next. Stan (MrMerlin) always says the same, but all the talk about ballooning torque converters and stretching driveshafts, etc. distracted me from what seems the common sense culprit.

I'm inferring that the rear bolt does pass through an indent that's supposed to retain it, but the driveshaft has been pulled forward such that the bolt is now bent and sitting on top of the splines aft of the indent?

Thanks

Captain_Slow

All -
I hadn't thought too much about it, but the distance I measured to the TT bearing is about 3/4 of an inch less than what Dwayne measured for his write up...and he has more shaft splines showing up front. I'm expecting HTH is spot on....assuming so, what is the technique for sliding the driveshaft rearward? Hoping the answer doesn't involve dropping the TT. If so, I'll bolt up the flywheel cover and exhaust and put this on hold until in the new garage with a house and prepare to climb the learning curve.

Captain_Slow

Splines before...



Splines after....



Forward TT bearing...

Bertrand Daoust

Jon,
Yes I was at Frenzy the last two years. Great event! Hope to be there again this year.
Thanks.

Everything looks normal to me in front. Including the first bearing.

Like Stan (Mrmerlin) often suggest, you should check the back clamp too.
It has an indent but can move forward if not well torqued. This can damaged the driveshaft.
You need to drop the exhaust to check that one.

It is a good thing also to change both clamp bolts too.

Regards.

depami

Really?

Then I guess even the Constantine Superclamp serves no purpose beyond factory clamping.

Mrmerlin

I would strongly suggest that the flex plate check and relieving the flex plate isnt complete until the rear pinch bolt has been inspected and properly retorqued to 66 ft/lbs with a drop of blue loctite.

Virtually every 928 that I check has the rear pinch bolt loose.

SO no matter what type of clamping device is used at the front,
the rear pinch bolt not being tight will let the shaft migrate forwards.

The cutout on the rear portion of the drive shaft isn't meant to halt the shaft migration its simply there to allow the bolt to pass through the clamp.
Though if the shaft moves far enough the bolt will be moved into the splines.
The solution here is to loosen the front clamp then tap the drive shaft back towards the transmission till the slot lines up.
This can be done with a pair of vice grips and piece of rubber wrapped around the shaft.
Then tapping the shaft rearwards, a helper is a good thing to watch the progress.

NOTE you dont want to nick the shaft surface as it could cause a stress riser, this could cause the shaft to shear

NOTE its a good idea to replace any damaged clamp bolts,
otherwise if the bolt looks good it can be reused its a hi grade bolt .

Captain_Slow

Stan (Mrmerlin),
Your timing is impeccable Now I understand....crystal clear. Details like not nicking the shaft are extremely valuable.

Thanks to all who posted. Very helpful.

I decided to pick up a dial indicator and magnetic base. Although I was really careful to measure in exactly the same locations and orientation of the digital caliper and do feel comfortable end play is within factory specs....I want to be able to monitor changes, which I can't do within the margins of error of my method using the calipers. The forward exhaust is bolted up and I'll try to use it as the anchor point for the magnetic base. Then I'll drop the rear exhaust and shields to check the rear bolt and full-length condition of the trans cooler hoses.

SeanR

Disagree 98% with this. The 2% is to replace the bolts after use. Of the hundred or so that I've checked, only 2 had a loose rear pinch bolt, the rest of them had front flex plate movement.