Well crawled under the car today, and checked my clamp, I could se metal in front of my paint line. So just a a reminder for folks to check. Released the clamp, and moved the tension off the plate.

I have a PKlamp on there. Checked the torque on the bolts, so all good there.

Quick question for the folks on the board, how often do you do the check, 6 Months or yearly. I was surprised to see tension on the plate. Not much, about a mm or so, but still disheartening to see.

 

Isn't the PKlamp supposed to stop movement?

 

Yea that is why I was discouraged to see the movement. As I said, it was not much. I should have put a good straight edge on the plate to see if it was flat with the movement.

 

well dont forget that the other part of why the flex plate is moving is because the rear pinch bolt is loose.
A proper check of the driveling is required,
and it includes removal and inspection of the rear pinch bolt.
I think its a better idea to use the old bolt if it is not damaged,
as the bolt will already have gotten stretched.
NOTE this is why its loose in the first place.

Once you have the bolt out inspect the hole for proper alignment of the rear shaft cut out to the input shaft of the transmission then install the bolt with a drop of blue loctite and torque to 66 ft/lbs

 

That you checked and found what you perceive to be a small movement is the victory here. Anything up to 3mm does not seem to do any harm [not that I recommend such].

What you should perhaps be saying to yourself is "would I still have an engine had the Pklamp not been fitted".

As I have posted many times, 16 years ago I had a flex plate that would not hold and Porsche could not solve the problem. Within two weeks of tightening up the [new] pinch bolt the thing would slip and an incipient vibration would appear at exactly 3050 rpm to tell me so [thank goodness].

I was the second owner to try Earl Gilstrom's Loctite solution and have used it on both my 928's with total satisfaction and no apparent detriment- the second iteration having been in place for over 10 years now. For all I know it may let go tomorrow but I have some comfort in the expectation I will feel the tell tale vibration.

The mechanically elegant solution is Constantine's clamp and the bolt on solutions have their own elegance due to simplicity of installation. Maybe with time even these have a shelf life if the underlying problem [that remains unresolved] deteriorates further due to the likes of crevice corrosion [for instance]- not an unreasonable expectation with the passage of more time.

Some folks dismiss the Loctite solution approach but I believe it is far more elegant that most seem to realise. Not only does it enable the original flawed design to work, by its nature it probably prevents further degradation of the splined surfaces by keeping corrosion out due to the nature of the bonding mechanism- the bolt on devices cannot achieve this and with the passage of time I can easily visualise why they may not last forever. The only downside is the ability to remove the clamp but if it does not need to be removed for 10+ plus years or so why should it be a problem? - the bolts holding it to the flywheel can be undone for removal purposes and once the job lot is on the deck it then easy to remove the clamp from the shaft [ask me how I know].

In your case I would remake the joint this time using the Loctite 290 approach, slap the PKlamp on top of that for good measure whilst the stuff is still green [i.e. immediately after you tighten the main clamp] and see how it goes. Worst case scenario is you are out $5 for a bottle of goo! That or get a Constantine clamp.

Rgds

Fred

 

I agree with your Loctite 290 comment. Did this in September 2005 too. My torque converter bearings were shot and while I replaced them, I also replaced the torque tube with a rebuilt unit from 928 International. The car had 110 kmiles back then and I decided (that was way before any "extra clamp" solutions) to secure the flexplate on the shaft with the Loctite method.
Today and nearly eleven years later, there is still no movement on the flexplate. After the Loctite 290 treatment in 2005 and 71000 km (44 kmiles), the thrust bearing still checks at exactly 0.27 mm.

I think it works (from my point of view).

 

Schocki,

As someone who has revamped oil facilities for 40 years the best solution when it comes to modifying an existing setup is invariably the cheapest one that works. At $6 plus an hour of labour this one takes some beating! The one Porsche should have supplied is available from Constantine - no question about that. If I ever have a need to pull the drive shaft I would seriously consider this upgrade route.

Interestingly, when I lost my late S4 some 10+ years ago the damage was so severe that the shock somehow managed to bend the drive shaft slightly just behind the splines- the Loctited flexplate hub joint did not let go during that event!

Rgds

Fred

 

Very interesting!

But I think if Porsche would have been smart with this, they could have come up with this idea on their own.
Tech bulletin, with a procedure on how to check the TB, release all the load, Loctite 290 application.

Note and instructions on what to do in case removal is necessary.

Best and most cost effective solution, but that's not German (believe me I know what I'm talking about)

 

The really scary bit was that back in March 1999, a few months after purchasing the S4 with some 75k km on the clock the drive shaft snapped for no apparent reason. I had noticed a vibration at 3050 rpm but being new to the car did not understand the significance. When the new drive shaft was installed the problem disappeared but returned two weeks later. It was at this time that we got the internet over here and I quickly found the Rennlist and this problem was being discussed. I immediately took the car back to the dealers and to my horror the flex plate jumped 3mm. The agents were not surprised- I was aghast. The dealers duly registered my concern and went back to Porsche Middle East with the problem and within the hour they got a return communication advising to replace the locking bolt and over torque to 110% of rated. If there was not an inherent problem how come they came back so quickly with this workaround- that did not work as I found out another two weeks later!

Fortunately Earl came up with the Loctite approach at this time and my S4 was the second car to have this done. In those days there were no "other alternatives".

Rgds

Fred

 

This is what they should have done- it would have saved so many otherwise good motors.

Personally for punishment I think someone should bomb the factory using a GR3 Tornado - know anyone who has one?

Rgds

Fred

 

I've put 66 lbs/ft on that pinch collar bolt and have checked it at every oil change and I still don't see any movement, or metal showing between the spray painted mark on the collar and splines. My mileage is very low though, no more than 1,000 per year so that probably explains the lack of movement.

Loctite 290... isn't that the Loctite Green stuff I see in Home Depot?

 

Andy,

Does the car ever leave your driveway [ha ha]!

What needs to be understood is that not all examples fail to hold but way too many do fail. If they all failed there would be no auto driven motors left by now!

My rationale is that the units are made within certain dimensional tolerance ranges and it may just be that some examples have [randomly] opposite tolerance extremes in the male and female components. Over time some fretting occurs and when such happens the thing eventually reaches a point where it can hold no longer. There is no hard and fast rules for failure but from what i have seen failures start to occur from about 70k km upwards whatever the reason for such.

As I remember the Loctite formulation was red but I dare say that is a dye that could be changed over time. I used the 290 formulation initially and later on used 270 when I could not find the former- the only difference I could find being the temperature at which the bond breaks [a little higher rating for the 270 I seem to remember] .

Rgds

Fred

 

Fred..... not lately.

 

Thanks everyone. I will do a search on the Locktite solution. I only put 60ftlbs on the bolt. Easy enough at this point to re-tourque.. Rear bolt looks good. I also pried the plate back a bit while tightening things down so maybe that was a bit overdone. Kind of doubt it though.

 

The rear bolt is no factor, the bolt sits in a groove and with this, the clamp won't go anywhere.

I think that the Loctite 290 solution is brilliant. I actually drilled an extra hole in the aluminium pan under the cats (my GTS has a Rogerbox). With this I don't even have to put my car on a lift. With my borescope I simply get down on my mechanics crawler and check for any movement. Quick and simple, no problems since many years.

Loctite 290: "best bang for the buck"