JET951

Hi Vilhuer , no its the same thing , there is no issue with the front coupling , never has been , its the rear coupling that becomes loose ( bolt stretch ) made worse by no one knowing its there

Vilhuer

No it's not. There are two separate problems. Both created by Porsche by changing automatic TT setup over the years. One you describe is also always present on manual gearbox car rear clamp. If you haven't ever seen both it doesn't mean only real problem exists. I have seen both on several cars and always check rear clamp bolt and TT shaft position compared to gearbox input shaft and do something to automatic front clamp design. Either change the clamp or entire center shaft to early design which allows washers to be used to prevent clamp movement.

By keeping this front end problem do not exist talk going you will lull some people thingking there is no problem. They will pay the price if they do not listen to other opinions.

JET951

Hi Vilhuer , if the front coupling was the issue there would be no deflection of the flex plate , because the male & female splines would just slide past each other , meaning the TT shaft ( quill shaft ) would move forward & the flex plate would remain unmoved

But instead the front coupling holds quite well & hence the shaft pushes the flex plate forward , this is very simple stuff , particularly when one sees at the same time that the rear of T tube coupling is loose or put another way much less grip at the rear coupling because the bolt has stretched over time

I / we recognised this decades ago "not last week " & this has been no issue at all to maintain , hence no ( I repeat NO ) engine thrust bearing failures in the large number of 928 models we look after

But I keep hearing people around the world still find this a mystery just amazes me

And you are correct , there must be opinions , its just that ours has worked with no issues at all for decades & you can learn something that I am trying to inform / convey from the 38 + years I have been working on Porsche cars

I must be doing something wrong with the way I describe how we do not have issues & how we solve a potential problem that I identified decades ago

OH its got nothing at all to do with the silly circlip , because we have seen at least two early 928s models ( yes the circlip versions ) that destroyed their engine thrust bearings , this was at least 15 years ago when we had ( over a period of about 2 years ) 2 X separate 4.7 L 928S engines that the owners were trying to find a way to fix & both these cars suffered Thrust bearing failures from the engine oil these poor things were on at the time ( yes so called synthetic low low oil film strength oils )

These were the engines that I was fascinated in , we had never seen such destruction before & it all came down to the engine oil , there was a big fad here in Australia that reached its peak about 20 years ago of switching from last century oils that were quite reasonably priced to the "NEW" expensive so called synthetic oils & its precisely coincided with oil companies selling these so called synthetics with very little ZDDP but instead Boron AW packages and weren't these oils terrible in last century engines & some were worse than others & hence these two early 928S 4.7 engines with the circlip on the front of the T Tube shaft , I should know because we had to purchase 2nd hand 4.7L engines & make one good engine out of 2 ( thats per car ) & we got the cars transported here & we installed the engines that we assembled , but we had to educate the owners that only 20w-50 oils to be used & all was well from then on

That is why I always try to let people know what we have seen & worked out over a very long time & yes we had to learn that the so called synthetics were extremely harmful to last century Porsche's at that time

If one wants to learn from what we have discovered then good , if not I couldn't care less

But do not say I didn't freely give some knowledge back

mike77

Thanks guys for the detailed responces. Jet thanks for sharing your procedure I hope to get onto this job sometime soon. My reading was 0.22 so within tolerance but as you say needs managed.

Oil wise I struggle to get my head around 20w for my climate and driving habits. Live in the city and the car sees a lot of short journeys to work, supermarket etc. In winter when the car is literally frozen with 5w it cranks and starts easily and gives me full oil pressure immediately. The 5w40 I currently use is sl rated and has over 1000ppm zddp, with oil changes less than 2000 miles I figure sufficient. The 5w50 is labelled racing and has zddp package of 1300ppm. Low mileage oil changes should limit the impact of shearing of the wide range of viscosity. If it was hotter here I would go 20w but I'm looking for an option that covers me for the 3rd of the year that it's cold.

Vilhuer

And so it goes on and on and on. You say center shaft moves. To what direction? Always towards front of the car? Against flex plate which is fighting hard to resist it? I have seen centershaft migrate towards rear when rear bolt is loose. That was on 5sp car.

You do realise we have measurements which show center shaft to be exactly where it needs to be and still front clamp has moved forward? Also visual inspection of TT rear end. Front clamp has moved forward on center shaft and not stayed still while center shaft moves forward. I also have seen migration at front when rear bolt was definitelly tight and not stretched. New bolt, just little driven, front clamp moved on center shaft and no red dust at back at all etc.

Yes, there can be problems even in early version with washers and circlip. They can be created for example by installing gearbox, TT etc. in wrong order. Oil film has definitelly effect on this also. Problem in your statements is that you are simply missing one of the multible problems. Everyone should look into what you mention as for example I do. It's just not enough.

JET951

Vilhuer I am not selling you anything , I am just giving info that we found works well & with no issues for free

And no the flex plate doesn't fight anything( let alone hard) , you can push it in any direction you like with you're thumb if you like , it just moves were is pushed & these always move forward ( via the moving shaft ) because its not being held at the rear

Why would the front clamp move forward , the front coupling is always tighter than the rear , because the rear index bolt stretches with acceleration events over time

Its that simple

Vilhuer

No it's not. I'm not selling anything to anybody. Usually I just spend my own money on products others make and I know I need. Just telling you and everyone else that front clamp can and will migrate. Do not ask why since no one has made case which everyone agrees is root cause. Just trust use when we say it does and do something to prevent it.

mike77

Is the front clamp worth arguing about? If we get peace of mind from either adding locktite or an aftermarket clamp then so be it. What's the harm?

My thoughts are that some of the old posts and guides out there that get found when you search the web ignore the rear clamp and people like me have been unaware.

FredR

Mike,

The key word in your post is "awareness". I have never had a problem with the rear clamp but it does not mean a potential problem does not exist and "de-facto" no need for checks to be made.

You clearly know what you need to know- and in my books that is 90% of the solution I would suggest.

Rgds

Fred