GregBBRD

Oh, I'm definitely not questioning that this is the problem, after all the hell they went through, to find it.

I'm trying to figure out if there are specific years that I need to keep my eyes open, for this problem, or if it is systemic to all the years.

Can you look in your door jamb and tell us your production date?

tda1

The build date appears to be 10/86 if I am reading the numbers correctly. I see a red number to the right side of the placard in the door jam. is that what you're looking for?

69gaugeman

I suspect that if a TSB was issued it would be for a deficiency that was discovered (a batch that had oversize holes for instance, or some rivets that were undersize or made of the wrong material.)

Rivets in this application are generally acceptable and the fact that they continued to use this fastening method would indicate that their testing showed it was good enough. Many flex plates are done this way. In fact, all of the ones I have ever seen have been done this way.

tda1

I can tell you that without it being removed from the car, the deficiency is virtually undetectable other than the annoying noise it makes when the car is at idol. The recommendation is to replace the rivets with new ones so they think the method is appropriate. Unfortunately they don't seem to hold.

Leon Speed

For those playing along at home, are these the rivets?

https://rennlist.com/forums/8084134-post3.html

GregBBRD

Great. That build date would suggest that this is before Porsche found the problem and presumably had the manufacturer fix the issue.

I'd be interested if anyone past the 12/86 build date has had this problem.

Chalkboss

I have a MY 87, and will check my build date and report back later. I would be very surprised if I do not have this problem- I have the rattle at idle and everything else has been checked/replaced except for that. Sound is coming from the TC area.
Rattle started a few thousand miles after the TT was rebuilt and TC bearings were replaced. I anticipate yanking the trans and fixing it in a month or so.

David L. Lutz

I have never posted on this, but after reading your post I thought I would chime in. Back in 2009 while I had the engine was out of MY 87, I rebuild my torque tube, replaced the TC bearings, and had the stall speed of my converter raised. I did not change the rivets at the time it was out and thought that changing the stall speed probably caused the rivets to start the rattle noise which I still have it today. Never changes, but tranny runs great and zero noise except in park at idol.

Funny think is I never had this in the 9 years before the work mentioned above and can't help to notice that you had the same thing happen after your replacement of the TT, TC bearings!

GregBBRD

I've got two pre-December 1986 transmissions apart. Both flexplates seemed tight, when I applied torque to them, holding them in a vice. One has no signs of anything migrating out of the rivets. The other had some dark streaks...almost looked like lubricant "slinging" off the rivets and across the flexplate. This one I took apart. The rivets seemed very tight and there was no sign of any wear on the sides of the rivets, however there was definite metal fretting between the shaft and the flexplate....it has been moving.

I will disassemble the other one and report back.

I sure like the idea of the rivets more than bolts. The bolts have threads, where they pass through the assembly, whereas the rivets are solid and exactly the right size. Seems like the bolts would be more prone to allowing movement than the rivets.

Tim968

My humble offering (speaking as barely-fledged noob, FWIW), the loose rivet rattle at idle was plain, (a light chatter more reminiscent of a cracked flexplate in a conventional North 'Murican car) in a low serial number '92 968 Tip that I learned up on before the current puzzle. A Different Beast, to be sure, with dramatically different 4 cyl. torsional driveline behaviour, but torque tube shaft nonetheless...and yes, the rivets were fretted and slightly rusty, play was easily felt after disassembly. The light chatter would disappear above idle w/ trans in drive....and this chuckle/rattle began 12 mos after replacing the rotted rubber flywheel damper. Wish I'd had the stones to drill them out and bolt up instead of buying new Porsche part with rivets. If you are wondering, yes; I don't get out much, lol. And, yes, it's reasonable to assume that factory
Was sourcing both 928/968 model line parts from the same jobber, I think. FWIW.

SMTCapeCod

Who modified your converter?
Did you have a chance to drive it with the stock engine and upgraded TC?
Interested in driving impressions, either way.

David L. Lutz

Edge modified the converter and when I reinstalled the tube everything went back in all at once including the converter. Engine was stock at this point (started the rattle right from the start). I did drive the car for around 400 miles before I installed the Super Charger. With or without the SC from a flat out dead stop to WOT it does get of the line faster even though I have no numbers to prove that. Driving it around town and now especially with the SC I would probably rather have it stock. It just seem you have to keep your foot in it all the time for start and stop slow traffic around town. No problem at highway speeds, no slip or "in and out" feeling even at 55

I lived in Mexico for about 8 years and street raced the car on a 1/2 - 3/4 mile straight road and having the mentality of that experience I was trying to modify the car to get off the line faster. Now with the problems in Mexico I am not returning to enjoy that party any more so I really have no need for the modified converter at this point.

murray928

Hi,This is my first post as I have recently acquired a RHD 1985 928 S2 which needs a bit of restoration. The engine is out at the moment (able to source lots of pricey bits) but am having trouble getting a transmission oil pipe return line part number 960.307.029.02. It's the one that connects from the bottom connector on the little oil cooler right back to the one that connects to the transmission assembly (part no. 960.307.039.00)The metal pipe on the old one is very corroded although the rubber parts seem ok. Can anyone suggest a workaround. I see stainless steel transmission cooler hose for Chevrolet for sale on ebay. Could something like that be used on my 928. Can anyone offer me some advice.
PS. I also need and cant get two little bonded rubber mountings part of the fuel injection system(part no. 999.689 001.00)
Any alternative suggestions would be appreciated.
Many thanks, John. (I'm Irish)