TheoJ

Hi, I need a bit of help here.

A friend has a 1988 928s4 and bad trouble with the automatic transmission. Almost no oil pressure, black tar-like oil, only a few liters. New oil and filter did not improve things. He wants to replace the box.

We can get a replacement (722 270 250 1 722 316 02) which is intended for the 1985/1986 model. Is this a drop-in fit of what are the differences?

Thanks for your help.
Theo

Maybach_Man

i have a replacement transmission from a 91 s4 but its in the uk

any use??? p.m . me

Geoff

John Struthers

Theo,
You need the good word from Jim at 928 INTL., someone from the other Big 3, or Steve Cattano.
FWIW
Listed:
MY 83/84
MY 85/86
MY 87/88
MY 89
All 4 spd auto's.
However, the core's are listed as:
AT1 - MY 78/82
AT2 - MY 83/86
AT3 - MY 87/89
Valve bodies are listed as: MY 83/86, MY87/88.
Torque Converters are listed as: MY 83/85, MY 85/86, MY 87/91.
And, of course, it's a safe bet there are differences in the flex plates, though the mounts should be the same.
Goes without saying...pull, inspect, drain, flush the TC, inspect all the slotted tranny cradle mount slot holes for deep wear... might as well drop the cradle as near every thing is off.
I believe the TT is the same unit from MY 83/95.
Enjoy

TheoJ

John, thanks for the info. This is what puzzles me... I seem to recall that there are mechanical differences between the 1986 and 1987 version, but I'm unable to find more detail.

Maybe Jim Bailey will chime in...?

borland

Per the WSM Vol 3, that is a type A28.07. 88' ROW came with a type A28.14.

Per the table in WSM Vol 3, page 30-0103, you can see that the gear ratios for 1st, 2nd, reverse, and final drive ratio are different.

I believe that earlier type also starts in first gear. That rolling to stop, downshift clunk into first, might not be too objectionable considering the taller 1st gear. I know on my car, if I drive it with the gear selector in 2nd, when I roll to a stop there is a noticeable clunk as it shifts into first just prior to coming to a stop. I wouldn't want first gear starts with my ratios; the car has plenty of power to start in second gear.

Vilhuer

Torque converter is different including its physical dimensions. Older 4sp do fit easily into body without changing torque tube or drive shafts.

Friend has '90 MY S4 box without diff available cheaply if it helps but there should be many options availalble closer too.

TheoJ

Hi Erkka,
thanks for the offer. So the 1986 will fit if I want it to. That is at least something. I'd rather have a good 1988 box but fear that shipping from Finland could / would be quite high.
regards

jon928se

Theo

85 AT into 88 will bolt straight in. The only thing which may require adjustment is the throttle position cable. Eric (Dragon) and I did it the other way round - 89 AT into 85. The white plastic "thing" that fixes the outer of the cable into the AT is different - 89 cable outer won't go into 85 AT. 85 cable outer is loose in 89 AT.

And while doing it make very sure you don't unknowingly pull the various pieces of the outer of the cable apart - This makes it impossible to then reconnect the inner which will have become relatively shorter with respect to the outer.

TheoJ

hi Jon,
now I remember where I heard about mechanical difference. It was Eric's car. Is it a non issue to attach the throttle cable in you opinion or does it require replacing the cable too?
Thanks

jon928se

HI Theo

When we discovered this the TT and AT were back in the car so we couldn't remove the old cable - it runs in a steel tube above the TT. I doubt that the engine end of the 88 cable is the same as the engine end of the 85 - 32v versus 16v.

We solved the problem by carefully cutting the fitting off the end of the inner bowden cable allowing us to remove the white plastic outer termination and swapping in the appropriate one for the 88 AT then brazed the inner fitting back onto the end of the inner bowden cable.

TheoJ

hmmm..... I think a new 1986 style bowden cable sould be considered upfront if we go for that 1986 tranny.

But apparently your fix still works in Eric's car. Good job.
regards,