WilST

+1

Noob question. Just purchased an '85 S4 with slipping and rattling auto trans. Slipping appears to be B2. On the rattling, from studying PET, it looks as there's a front and a rear flex/drive plate. Should the rivet-drill/nut-bolt replacement TSB be done on both plates? Thanks.

Avar928

There's no such thing as an '85 S4, only a S3. Probably should make an individual thread to address both issues. Slipping could be quite a few things. TSB is for the rear flex plate.

WilST

I'll study up on the S3-S4 issue. The slipping threads I've read answered all my questions so far, I was only asking about the flex-plate rivet issue.

What's the flex-plate TSB number, hopefully it's on the Morehouse CDs?

Avar928

TSB 8609: https://rennlist.com/forums/928-foru...er-rattle.html

The S3 and S4s have completely different exterior styling in front and back, engine intake is also different. Google a picture, easy to tell.

Imo000

Make sure they DON'T reuse the flex plate bearings.

WilST

Avar, thanks much for the info . The TSB 8609 capture in that thread looks to be from the Morehouse CD, the bolt part nos. didn't make it through. Found them elsewhere, the missing bolt part no. is:

8 Bolts N 010 240 7

GregBBRD

This is such a great thread, by all of you guys!

This thread should be bookmarked and be used as reference material for anyone with a drive train noise!

And you really have to admire the shop that TDA1 used to do this job! That tenacity is very difficult to find, these days!

Great job all!

tda1

We're back in business! The car is fixed the noises gone. It turned out to be the flexplate inside the bell housing of the transmission. They replaced the rivets nuts and screws and bearings and there's no noise whatsoever. The car drives totally different acceleration is much better. Shifts are smooth and crisp. I'd like to thank all the guys on reenlist for their support in helping me through this. Also the guys at ASG were terrific.

WilST

Well-fought battle, and really interesting thread. Well done Sir!

Chalkboss

Great news. Glad this can be put to bed. Gives me some confidence that my rivets have given up the fight and are loose. Hate that damn noise, it's embarassing in such nice cars as these.

Imo000

Excellent! I bet this is going to be the last time that shop will take on another 928 transmission job.

rnixon

I'm glad that it's fixed, and hope that you weren't deprived of too many beer tokens in the process. Enjoy!

snoz

Well hell yeah! Awesome news and glad to hear it!

GregBBRD

I actually feel a bit left out....

For all of the vehicles I've had apart and for all of the transmissions I've rebuilt....I've never seen one of these flex plates with the rivets loose. Never. Ever.

The technical bulletin for this problem is dated December 16, 1986 and says that it covers 1985 through 1987 models. Yet, Porsche continued to rivet the flexplates all the way through the entire 928 model line. It would not be like Porsche to keep installing a weak part, which required a repair a couple of years after production. So it would seem that they must have "solved" this problem after the December 16, 1986 date?

So are we to assume that this "rivet problem" was for a "short run" of flexplates and the problem got solved after this date?

Anyone know?

What is the date of manufacture on the OP's vehicle?

tda1

Greg,
I saw this first hand. I went to the Transmission shop and he had the flexplate in a vice. He said the only way you would be able to feel it moving was to press it out of the bell housing and put it in the vice. He had a pair of vice grips attached and told me to grab them and see if I felt anything. I felt a wobble as if there was a 1/2mm or so of play. Apparently that's enough to make that god forsaken rattle sound.
I can tell you now that it does not make a peep. It feels like a totally different vehicle with the rebuilt/new transmission and correctly oriented throttle cable.