jon928se

Michael

Re your last sentence (well theirs actually)
"I can see them arguing that one shouldn't even bother checking protrusion
( 2.00+.5 ) as long as the bolts match the grooves."

This does not apply to your car . FULL STOP

If they keep saying this you have them over a barrel because all the stuff in the WSM about measurements and clearances is only relevant to earlier cars (ie 3 speed Autos Pre 85 or thereabouts someone chime in and correct me if I am a bit out). The WSM is quite specific by implication that there should be no pre load in either direction in the crankshaft to drive shaft to transmission assembly.

Re the rest of your post -

I need someone who has taken an Auto transmission off to inform us how much play there is in the double clamp at the rear. I have only done a manual 5 sp and it all seemed to go together really easily but I had the clutch out at the same time so it was easy to just slide the drive shaft around to make the clamp olts go in.

Jon in NZ

PS the Stone Grey GT is still in the Garage following a Porsche alarmectomy. I will restore the wiring back to at least factory standard and repair damage Porsche Cars UK did to the wiring when they installed the UK specific alarm and immobiliser

Vilhuer

At least one '84 model year Euro S with 4sp automatic I know of have earlier design with preload washer and lock ring. Believe it came from factory like that. By the way what is opinion in here about applying preload to these older cars? Should it be set to same, larger or smaller than 0.3 + 0.2 mm.

AFAIK all automatic and manual clamps are basically same design so manual experience is directly transferable to automatics.

On my experience it's possible to bolt at least manual car clamps in about 5mm range. Maybe 3mm is easy and one or little more than mm at each end requires some force to do. To get single clamp mounted 10mm off is going to be difficult unless new groove is made on center shaft for the bolt. If clamps at both ends are all done in suitable extremes of their range then maybe 10mm is possible as combined "wrong". Shops claim that preload do not need to be checked at the front of TT is obviously wrong. I just find it hard to believe their 10mm statement unless metal was removed from center shaft or all clamps were opened and mounted wrongly.

If I have understood right car does still have at least some parts of TT what were in the car when damage occured. If true there should be signs of wrong mounting in them. Clamp bolt destroys it's thread against center shaft grooves side when clamp is wrongly mounted. Even if bolt itself is changed center shaft should still show this damage. TT would need to come apart to really get bottom of this.

victim

Hi All
Erkka, please excuse my ignorance; are you talking about axial play?
Five mm of axial play on the clamp/grooves?

If you are right it blows their argument right out of the water....
Can someone confirm that or tell me I'm in la la...
( Maybe send me a sketch? lemongra@bigpond.net.au

Thanks Jon for the comment although its hard to picture a clamp ( I've got one sitting in my boot and a bolt as well. Bought it just out of curiosity ) that's splined and not exactly spring loaded, untouched for so many years just slip off. Someone at weltmeister told me they've seen a lever being used to loosen it and you know what happens when they do that don't you - the shaft moves.

Regards
Michael

We were talking about the se last night over an outstanding red..

Vilhuer

Mis-using exellent 928 International website once again.

At front this plate is bolted to flywheel with six bolts, three pairs at outer exges of triagles.



As I have understood above plate and it's center clamp was not touched during gearbox repair. So it's bolt should have stayed where it was put previously. From the previous messages I believe it's been like it left from factory until TBF occured. Anyway, clamp mounts to front end (left end of next picture) of TT center shaft.



Crank shaft inside engine do not stretch 10mm, neither does TT center shaft without snapping into two pieces (not when it's in car). Front flex plate tries to fight any fore-aft movement (too well in fact, which makes TBF happen so quickly). This leaves only rear clamp as variable what could have caused 10mm misalignment.



I believe it's difficult to mount rear flex plate (above) inside torque converter housing so that it would stick out more than factory intended. That is if both bearings were installed correctly, are correct type (not too narrow) and spacer between bearings is mounted also etc.

Now if rear flex plate is where it's supposed to be there is only one thing that can go wrong in installation. Can't find picture of rear flex plate tube clamp it self but it's similar to two clamps in manual transmission front clamping tube that was also used in 3sp automatic at the back. There's also shorter version of the clamp that was used on early '78 models, both manual and automatic I believe, but lets leave it out of this.



Reason why clamp is not welded into flex plate tube like they are on above tube is that those two bearings require it to be removed when they're changed. On TT center shaft there's similar groove as is on clutch shaft (below).



Rear flex plate clamp bolt needs to go through the groove in order for it to go to clamp threads. If groove and bolt hole on flex plate shaft do not align it's impossible to tighten the bolt. Unless material is removed from TT center shaft or/and flex plate shaft that is.

Since rear flex plate clamp is not permanently mounted on flex plate tube it might give some mm more room to get center shaft <-> flex plate tube connection mounted wrongly. I do not believe it's possible to get this connection so badly wrong that it alone would create 10mm difference at the crank. 10mm would mean that there would have to be 20mm space to clamp two parts together wrongly. 10mm fore and other 10mm aft. Unless of course for some reason front clamp were at extreme front of it's moving area. Not likely if it was done at the factory when all involved parts can be presumed to be it their right places.

Since front flex plate clamp is in fact permanetly welded (I believe) into tube it is even less likely to be the single source of 10mm wrogn alignment. Unless new groove was made into center shaft for clamp bolt. Both front and rear clamp together could maybe barely give 10mm. But I think front clamp would need to have been open simultaneously with the rear clamp for it's bolt to move approximately 5mm towards the rear and thus taking half of the 10mm.

If gearbox were taken out so violently that front clamp would have moved half or more of the 10mm it would have created serious issues when box was put back. I would expect front clamp and entire TT center shaft to have moved at least part of the way back to normal position if rear flex plate clamp was mounted when box was not fully in and then box was pulled to the TT with mounting bolts. It's not too difficult to take out bell housing cover and check TT center shaft. There should be serious signs in it if this is the case.

In conclusion. I believe it's extremely difficult to get 10mm movement out of one single clamp. But if I would need to do it I would try on rear as there clamp is separate part. There are two possible points of failure in these parts if we leave out more complex scenarios.



In Las Vegas rear clamp would have smaller odds.

Hope this clears up what I mean. Also hope above data is correct, not false. Last thing you need in building your case is confusion what is and what is not possible.

victim

Sorry Gentlemen, we're obviously talking about different things....

My original question:
" I can see that bolting the trans back to the TT and aligning the grooves and clamp is a fiddly process and difficult (right?).
I can see that the process of aligning and clamping the double clamp can actually cause pre-load. Right?
Therefore the claim that the pre-load is the same if everything bolts up nicely is uneducated. (incompetent?)"

I was referring to the Double Clamp (Not flange clamp) clamping the drive shaft to the converter. The claim by the workshop that if the two bolts of the double clamp match the grooves in the drive shaft and the converter shaft, the drive shaft would then be in the same old position ( or protrusion relative to the TT flange) as they were before the trans was removed. According to them there was no need to check the flex plate - the cause of all my problems - if it all fits back. I further said that a judge could be conned into believing that; it makes sense - if both screws align with the two grooves then everything must be in the same old position and hence ( the workshop argued )there is no need to check the flex plate.

BUT, as SharkSkin #65 pointed out ever so clearly, the grooves and bolts in the rear are not a precise fit and are not designed for precision positioning ( the workshop said they are precise!!) of the drive shaft. The tolerances in the front ( flex plate / crankshaft ) are far more precise than the tolerances in the rear. ( I mentioned protrusion +/- 0.5 ) I then asked aloud, How could a workshop with expertise make a ( uneducated? ) statement like that?

I further inquired if the double clamp in the rear is easily unclamped and reclamped (on re-fit of trans). I can see that this process of unclamping and then re-clamping ( especially reclamping ) is a very difficult one and probably fiddly ( knocking, tapping, levering??) Yes? If it is as fiddly as I can imagine it to be ( someone confirm or refute this please ) then we are introducing innacuracies ( and movement? ). As a 928 owner who went to an official dealership ( to purchase the car and to service and maintain ) I feel it was not given the precision-like or professional-like treatment that it deserved. I could be wrong...

Cheers All

victim

They ( workshop ) said it's not possible to move the positioning of the drive shaft if the grooves and bolts align. SharkSkin refuted that quite clearly but I was after a more empirical explanation.

Thanks Again

Vilhuer

Lets get to the bottom of this. I was under impression that there is only one clamp at the back of the TT and it clamps this



directly into rear (right) end of this




On older 928 versions there were this



at the back of the TT between this



and this




For your case it's very important to know if sequence of parts is A:



or B:



If it's A I'm reading PET wrong. It wouldn't be a first time. A makes 10mm much easier to get from the rear than from the front.

If it's B it means workshops statement about double clamp is flat wrong. You have better case IMHO if actual design is B meaning they don't even know what they're talking about.

It's true that having A type parts would allow some (more) adjustment in reclamping box back to car. If I were doing it I would be very curious to know why I would need to go to extremities of the double clamp to be able to mount box back. 10mm wrong in the front clamp would mean I would have to do it as TT center shaft would have changed position when gearbox was taken out. Front flex plate would have moves TT center shaft to relieve the pressure and part of the 10mm pressure should have gone away. They can't seriously this there was even more wrong than 10mm to begin with? If I were able to mount both double clamp bolts back to their center of movement range it would mean front clamp were source of all 10mm's. Now if front was only wrong why would it start to act up only after gearbox was reinstalled?

No matter if design is either A or B (or C?), workshops position do not make sense to me. 10mm is too much movement from one clamp and only barely doable from two. They should have seen something was seriously wrong.

Tails

Michael,
I have been working on the reasons for the migration of the forward flexplate clamping piece for the last couple of days and I plan to write a hypothesis on what I believe causes the migration that exerts an excessive forward axial load onto the thrust bearing causing failure in service, however, this migration does not appear to be what happened in your case. As it would appear that you transmission was installed incorrectly after repair which imposed excessive forward load to the forward flex plate and subsequently on the thrust bearing. Up to 10mm as stated by PCM.

However, I have just read the last couple of posts and Vilhuer is correct in his question, you need to get the answer of what type of flexplate assembly is fitted to the aft end of the Torque Tube.

I was viewing this today in PET and I noted the aft flexplate assembly was changed in 1986 when in that model year changed the automatic transmission from a 3 speed to a 4 speed auto.

3 speed autos are fitted with a clamping sleeve with 2 clamping screws and the 4 speed autos are fitted with a single clamping piece and 1 clamping screw. And the clamping pieces with a single clamping screw were installed right up until the end of production with the 1995 GTS. This assembly is clearly shown on page 37-130 of Volume 3 of the WSM for vehicles manufactured from 1987 onwards and the mounting of the flexplate to the torque converter is shown on page 32-102 of volume 3 which again show the single screw clamping piece.

I also noted in the WSM that when the torque converter is assembled onto the drive shaft of the gear box there is a requirement to check, prior to disassembly and reassembly, that there is approximately a 28 mm distance from the end of the bell housing to the flats of the flexplate mounting on the torque converter for 1987 onwards and for vehicles up to 1986 it is approximately 16mm, reference page 32-105 printed in 1987.

You will note that this is not an exact figure, however it is interesting to note that the difference in reading is 12mm and PCM said that the forward flexplate must have had a preloading of 10mm by some other mechanic, is this a clue of what might have happened at PCM?

Could PCM adjusted the distance from the front of the aft bell housing to the flats on the torque tube to 16mm instead to 28 mm during reassembling the automatic transmission?

To allow me to test this hypothesis could I again ask what actually failed in the gear box, was the gearbox removed, was the torque converter removed, what actually happened, can you give us some history?

We know that there is forward migration of the front flexplate clamp piece, in service, which commenced, I would suggest, with the installation of the 4 speed auto box during 1986 and in my case the forward movement of the clamp piece in my car was measured as 3.08mm in February 2004 when I checked it and reset it to ZERO preload.

In your case was there any migration of the flex plate prior to the gear box failure? This is something that you will possibly never know unless you can check the clamp piece screw, however, PCM would probably have to had slacken off the clamp piece screw to remove the engine, however, this does not preclude you asking this question via your brief?

If PCM say, actually set the torque converter to 16mm depth below the face of the bell housing, the drive shaft protruded from the aft end of the torque by the specified amount , upon installation of the gearbox PCM lined up the clamp piece screw with the recess in the aft end of the drive shaft and inserted the screw, then tightened up the aft torque converter bell housing to the torque tube and then locked up the aft clamp piece screw, this could be the cause of the excessive load on both the forward and aft flex plate to the tune of 10 to 12 mm and in consequence put the excessive load on the aft collar of the crankshaft and the aft face of the thrust bearing, which could have caused its failure in such a short time.

If this hypothesis is indeed the correct one, then did PCM fit a shim behind the torque converter to set the distance to 16mm instead of 28mm or did they just insert the torque converter onto the gear box output shaft to get the approximate 16mm, which they may have thought was the correct distance required?

Again I believe that you will never know the answer to these question, as I would suggest that in the total strip down of the engine to see why is seized and it subsequent rebuild PCM would have probably double checked all clearance and set up required from the engine crankshaft end float right thought the final box up when the forward clamp piece was locked with no preload.

As we do not have the full history of all that has happened, so it is difficult to come to a conclusive answer as a statement of fact of what actually happened.

Incidentally a fact can be as follows:

A fact that can be something that can be verified;
A fact can be an assertion;
A fact can be a belief; and
A fact can be something that you "just don't know".

Tails 1990 928 S4 Auto.

Garth S

I'm glad you picked up on this same issue as I raised in post #21 of this thread.
quote:

"Thirdly, the subject of torque convertor installed depth: In WSM 32-104, it states that up to MY '86, install convertors to ~ 16mm depth in the case. For MY '87 on, this dimension changes to ~ 28mm .... an obvious 12 mm change. Later on in reference to actual convertor installation, WSM 37-139 , point #7 clearly states that " measure installed depth of convertor( ~16mm) and note value for reinstallation." So the question is ... if it were possible to install the convertor in a S4 transmission at the wrong depth following a blind misread of the WSM, could the prop shaft be driven forward ~12 mm too far? - or at least far enough forward until the front flexplate bottomed out against the flywheel causing the prop shaft to forcibly slide through the splined coupling??
So much for speculation as to how one could screw up .....".

The convertor installed depth appears to be a plausible avenue; however, I've no first hand experience in this. Input from anyone experienced in assembly would be valuable, for this potential for error has at least stimulated two speculators ...

jon928se

Garth

I wondered about the issue of the Torque converter being installled to give a 16mm or 28mm "depth" depending upon which transmission it is, but it doesn't appear that it is actually clamped in place at that depth ?? - It sits on splines of the input shaft to the auto transmission so if you set it at 16mm then it will just slide in to 28mm if thats where is should be ??.

Something tells me this is not the answer to Michael's (victim's) problem.

Garth S

Jon,
That's where I need a reality check - for I've never had one apart in my mitts, and the WSM is a poor substitute for fact. I have a contact to make Tues who has worked on Mercedes units: while thet are not used by Benz in a transaxle configuration, he will certainally know more than I. At this point, the issue was raised as a text book loophole noted in the WSM.......

victim

Hi All
Thanks for yr latest posts but I just need time to decipher it and take it in before I say (or do ) anything presumptious... But do keep it coming. Eventually this prob of mine would see it's day in court so I'm also working on the legal aspects and engineer's report (and run a restaurant) as well.

Tails on re-reading yr earlier post I realised I had missed one of your queries.
The precedence that I mentioned was a Sydney case and the repairers were apparently trans specialists. The car seized after three months. Discovering that was a huge thing for this case cos it came complete with reports. If I win - correction, WHEN I win - this case, I know, and YOU should know, EVERYONE had helped. The guy who posted a simple list a couple o weeks ago RIGHT HERE and suggested getting onto "landshark" - I think it was UKkid - had helped and I took his advice. From landshark I got onto landsharkoz - a great bunch of guys. It was from there that Nick contacted me and also asked his mate with the unfortunate "precedence" to contact me and they came around quick and smart. A few great reds later my faith in mankind and brotherhood is healthier than ever.
From there it was downhill...
Oh, yes I am grateful to Garth cos he's the guy who pointed me to this site and I can see some good things here...thanks All
Michael
Keep it coming even if it's simple.

Vilhuer

Two fundamental questions I'd like to see definitive answers:

1. Design A or B (or C?)?

2. Is it possible to install rear flex plate to torque converter carrier so that flex plate bolt mounting point to TT rear mounting surface distance is wrong?

Answer to those will have large impact on this case. IMO these will even outline strategy how court case should be handled in order to have best possible chance of victory.

victim

--------------------------------------------------------------------------------

Erkka

The answer is, I don't know and I don't even know where to start except perhaps go tp Porsche ( they're not speaking to me ). I'll call the spare parts guys unless one of you out there knows.
Regards
Michael

victim

by Tails #83

Hi Tails, Erkka, All
I've really just had a chance to read and re-read your posts.
I have some explaining to do:

Tails, the gear box did not fail. Around mid last year the car wouldn't kick into forth gear. It only happened two or three times i.e. stuck in third. By the time I took the car into the workshop it was really doing everything right. But I had booked it in so I took it in any way. The report from the w'shop was that the trans was worn; some discs were worn and needed replacement. After this trans work the car was not driveable; I couldn't get it to kick down to first. On rare occassions , when cold, it would go klonk into first like a jackhammer and with a big jerk forward.

Other times, on foot down it felt more like second gear. Prior to the trans repair when I put my foot down, without fail the car would either take off screeching like a rocket or spin on the spot. This I never achieved anymore and beside it felt sluggish on foot down; like something holding rev back.

Four months after the trans repair they rang me from the workshop and told me the car had seized. The report says, " stripped engine and found thrust face of crankshaft seized. Determined cause due to poor alignment of crankshaft to front shaft therefore putting excessive pressure on rear crankshaft bearing and failing over time."

When asked to look at the bearing, only a small piece the size of a finger nail was all that was left to show.

Further, the w'shop claimed that the misalignment was caused by previous work two to three years prior - the engine was not refitted properly. Could they have caused it while repairing the trans? No, they said, the shaft does not move. It cannot move. I then visited independent Porsche specialists and was told the drive shaft moves; that in all likelihood they had caused it. When this was put to them they said it didn't move it because the bolt in the clamp fitted the groove. So, they said, if it fits it must definitely be back in the same spot. But, I protested, the bolt and groove are not precise fits - there must be some play, say, 1 or two mm? Hah, they said, the misalignment was in the order of ten mm.

I then went back to the (indepd.) w'shops and asked to look at the clamps, manuals etc. I was shown 39-49 (1982) and they even gave me the square coupling clamp (as a lose item) so I PRESUMED that was the clamp in my car. All along, I thought the double clamp (square coupling) was what I have. Now, I still do not know for sure. So I hope someone can come forward and clear this up.


by Vilhuer #79

Pardon my ignorance on this excellent forum but I intend to get to the bottom of this...but a quick question, Erkka : In the B arrangement that you illustrated it shows the rear flexplate with a clamp at the (front) end. I take it the clamp is welded to the rear flex plate shaft? So the clamp does not move relative to the flex plate. What about the bolt position for the bolt that clamps the drive shaft? IS THIS BOLT POSITION FIXED relative to the rear flex plate? Or is it movable? In other words is any part on the clamp movable; can you move the bolt position to align with the groove (on the drive shaft or the flex plate shaft for that matter) or do you need to move the whole rear flex shaft / clamp assembly (welded?) in order to align with drive shaft groove?

Regards
Michael