srupp1969

hi,

as I have a 4-speed auto out of my 87' s4 lying around in my garage that needs some overhauling I remembered that there is also a amg kit existing.
I don't want to use org. Porsche parts if there is a kit capable of handling more torque and therefore have some questions:

- Has anybody reworked his auto gearbox with this kit and what were his
experiences
- How much (more) torque can it handle
- Is it a complete kit offered by DC to be ordered by any Mercedes dealer
- Does anybody have part/order numbers of the kit
- What is the price for the kit

Thanks for your feedback
Stefan

Nicole

Hi Stefan:

This is a question you might want to ask Steve Cattaneo. He's a member here and owns a transmission shop on the East Coast. He is likely the most familiar with your question...

Viel Glück!

IcemanG17

Steve Pappin from the LA area also had his 4 speed rebuilt using AMG internals.....but he sold his 928 and doesn't frequent this forum much anymore.....he quoted it as being able to handle 1000hp.....vs 5-600 for the stock transmission!

heinrich

great question

atb

Hi Stefan,

Steve C. gave me the following advise (sorry no AMG part #'s) several years ago in preparation for my stroker build:

He lurks on the list, hopefully he'll have some additional input.

srupp1969

Hi@all,

thanks for the input.
Hopefully Steve C. is reading this thread

BTW:
In the german pff-forum (Nicole surely is aware of it) is a thread posted at the moment, where a 928 GT driver is looking for a possibility of cooling his gearbox via an external cooler to avoid overheating.
Any ideas from somebody on this?

Vilhuer

Easiest but not cheapest way to do this is to use GTS gearbox parts and Porsche cooler at front sama way as in manual GTS. Oil pump is in gearbox rear cover and run by 80+ teeth gear in differential in place of speedometer magnet plate. Does gearbox have speedo pickup in differential or is it from ABS sensors already? If it is early style GT box things get more complicated as factory pump would require change to ABS system.

In any case I think its more important to cool differential oil than spray cooled oil into gears. If oil is pumped to gears its better to pump it different position than what was done in GTS gearbox. Some have sprayed it to upper gears when in factory version its directed directly between meshing gear pairs. IIRR there should be something in archives about one GT gearbox which has aftermarket pump system installed.

hacker-pschorr

What is the estimated limit of the Mercedes auto? Todd has yet to have transmission problems, even after 24psi on a 5 liter, 15psi on a 6.1 liter and every other combination he's tried. He is running a stock 1990 auto with the PSD hooked up to a manual control to lock up the diff.

Just curious - Todd has yet to run his car on the dyno with any configuration. That will change very soon with his latest engine.

martin D

Stefan
These are pics of a cooler fitted to a GT g/box . The pump was an electric water pump (marked 'wasser', it was German). I hope they help.

In & out fittings on g/box



cooler,pump & oil lines. The cooler was mounted just behind the rear PU.

srupp1969

Hi Martin, thanks a lot for this info.

I have forwarded it to Bernd (nick: BB928GT)in the pff-Forum (www.pff-forum.de) and I think this might be very helpful for his planning.

@vilhuer,

also thanks for that info. It looks like if Bernd has also thought in this direction, but it is as you also mentioned a question of budget.

Cheers
Stefan

BB928GT

Martin, thanks a lot for the pictures.
In this solution the oil is taken from the gear end of the gear box rather than from the differential end.

On a sketch of the gear box that I have in front of me, one can get the impression that the manual gear box has two oil sumps. One under the gears and another under the differential. Even on the photos above it looks a though.
=> Is that true (two sumps) and is it possible to pick up the oil on the gear box's rear end (in the PET I can see outlets on the rear side that could be used for that).
As Erkka I also suspect it is rahter important to cool the differential. The temperatur problems I have encountered with my gear box (a '91 GT version) also second that assumption.

Regards,

Bernd

Vilhuer

There are two sumps (gearbox side and differential side) in all 928 manual gearboxes but they are connected about level where oil surface is. So in that regard it doesn't matter what end pickup is and where oil is pumped back in. Surfaces will even out on their own.

If I was planning on cheap pump system into late style GT gearbox I would look into how much GTS parts cost and install only pump and cooler at rear end, not entire system all the way to front. I wouldn't bother installing spray bay to cool gearbox side. Instead would just put oil back into box from differential fillup plug or slightly above it. So all that would be needed is GTS gearbox rear cover, oil pump plus its running gear on differential side, check valve in the cover and banjo bolt on top to take oil to cooler from Porsche and custom oil cooler mounted inside rear bumper and few self made oil lines.

This is factory setup in GTS gearbox. Spray bar has different size holes in it, one hole for each gear. They grow in size further back the bar ending to largest hole in the end which points to backside of differential gear. Besides these there are few parts which purpose is to collect and feed oil into pinion bearing.





















This is differential side of earlier ('85 in this case but all years up to '91 are same) gearbox. Bearing support would get in the way of the spray.



More complex home made version in older box.

http://members.rennlist.com/pageauto/transmission.htm

heinrich

Some of us aren't so blessed that we have GTS boxes, we have regular old S4 gearboxes

Vilhuer

Make me an offer and I put it back together with new input shaft/5th gear, new syncros (all six), all (they cost close to $1k in total) new bearings (except pinion bearing which is close to $1k alone) and new seals.

heinrich

So ... the offer would have to exceed the value of my house? 1000 + 1000 = 2000 and then the cost of the box .....