OSP

Today I ordered the Y pipe and RMB for my 84 928S... and now that I have found a mechanic to do the work, I am looking for detailed info on the TC mod that so many people here have recommended.

From what I have read, the oem spec is 1950 and I should be able to have this modified to 2300/2400. When I spoke to Carl at 928MS, he was not aware of anyone who had done this with an AT.

Can anyone share with me their experience with an AT and dirty details of the work?

thanks

hacker-pschorr

These two threads should answer your question:

https://rennlist.com/forums/928-foru...converter.html

https://rennlist.com/forums/928-foru...sed-stall.html

GRTWHT

My '81 928 (4.5L 3 speed auto) has a stall speed of 2500RPM.

Glenn
'81 928
AU

Mrmerlin

Warning more than a few owners have added vibration to the drive line by adding a modified TC. First question what are you trying to fix?
The car your working on is a GT car, its made for long cruises at high speeds.........

OSP

Trying to get more "off the line" power... in past posts, many have suggested this as a very good starting point. That said, I am looking to find out more specific details on how this is done.

GregBBRD

We've had "interesting results" with the Edge units....

I wish they had something that was predicable and worked every time, but every single one seems to be an experiment and they don't seem to be able to predict the outcome, very close.

I've been using "Euro" convertors, on my customer cars.

David L. Lutz

I am one of the "few"! I'm not 100% sure the added vibration to my car is the TC mod. , but I am fairly certian it is. I replaced the Torque Tube at the same time but I just don't think the tube is causing the vibration under hard acceleration.

Raising the stall speed does help you off the line and if you keep your foot into it the car is more responsive, but there are other trade offs that you may not realize. I can't speak for the '84, but on my 4 speed auto it has caused me shift problems, vibration issues, and to me just does not cruise at lower speeds (50-60) as smooth as it did before the Mod.

In summary, if you want to use the car as a "normal driver" I would not recommend it. But if only interested in "more go" it does help.

I did speak with Steve Cattaneo the other day about a future Tranny Project and we briefly discussed the modified TC. His comment was it is a must to match the TC stall speed modification with the torque curve of the engine and wanted a Dyno of my engine before we decided how to modify the TC.

(Steve DID NOT modify the converter in my car now)

OSP

I spoke to Edge to see if they could do a swap out... I am concerned about the down time for the mod. Buying a Euro would be an interesting option... where did you buy them?

GRTWHT

Try and look for the unit thats in my model car.

Modified TC's are a hit and miss affair unless you find someone who has done stacks of them and has got it right.
I used to get Torqueflight T/C's modified and never really got them to stall properly (it was cheaper this way and I was only using the car for the strip).

They get cut open and have the vanes of the rotor and stator re-positioned to slip. But thats just it, they slip rather than stall. Caused alot of heat buildup by bashing the oil around more. They are harder to balance and often the externally welded balance weights fly off - PITA.

Proper high stall converters are selected from engine torque vs RPM, car weight, final drive gear ratio, grip and a few other things. It's a drag racing thing and thats one thing the 928 is not.
The last car I had a highstall fitted to was set to 5000RPM with a trans brake!

Cheers,
Glenn
'81 928
AU

OSP

I spotted a TC from an 1982 Euro 4.7L. Anyone know if this would work my 84S???

danglerb

I think 83 was the split from 3 spd to 4 spd, so I would have my doubts, but could be.

As I understand it, which is not much, several Mercedes models used a 2450 stall TC that might work, or might be the same part as the TC used in the early Euro 928 transmissions.

OSP

wikipedia states that ROW cars went to 4 speed AT in 84, USA in 83.. so i assume this would be an issue placing a TC from a 3 speed in a 4 speed AT car...

Vilhuer

Correct.

Mrmerlin

ask Steve Cattaneo

Mrmerlin

Ask Steve Cattaneo