Pelican Parts Forums - 88 Automatic and 89 automatic compatibility

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88 Automatic and 89 automatic compatibility

The transmission, torque tube, and torque converter in my 89' S4 needs a full refurbish.

I picked up a good transmission, TC and TT from an 88' S4, and want to put them in while I rebuild the original units.

Question....

Are they compatible? I looked at 928 Intl... AFTER I bought the 88 parts... I hadn't thought anything changed between the years...

Will it work?

it should not be an issue. if the parts from the '88 are good, why rebuild the '89 stuff and then swap it back in? (unless you can't be without the car during the time it takes to rebuild to original parts?) ;)

--Russ

Yeah, I'm using this car as my daily driver. I intend on swapping the mess of it in a weekend.

From what I understand so far in searching the topic is the 89 has a 2.54? final ratio, where the 88' had a 2.20. Also the 89 is supposed to have a different shifting program that allows the shifts to occur much higher under WOT...

I got this information from www.928registry.org

1988 928S4 - 4-speed Automatic (DIS)5.0L-32v M28/42 (HP/TQ)316/317 (CR)10.0:1 (FDR)2.20 (0-60)6.6 (TopSpeed)162
88' 928 S4 automatic shift program changed for second gear starts (hard acceleration starts will be in 1st gear)

1989 928S4 - 4-speed Automatic (DIS)5.0L-32v M28/42 (HP/TQ)316/317 (CR)10.0:1 (FDR)2.54 (0-60)6.3 (TopSpeed)162
89' 928 S4 automatic gets revised shift program (holds a gear longer when accelerator pedal is to the floor)

It looks like the 89' has a much better 0-60 speed which I desire more than high speed flying. Wondering the difference between the transmissions where the "shift program" is concerned. Can the parts be swapped over to make the 88' shift and act like the 89' unit? Also, I know the final drive ratio can be swapped, but how much of a job is that?

What are the numbers off the bottom of both of your transmissions, not the registry what it should have, but what both of them actually are?

Trans ID number is stamped into the metal, not raised like a casting number, and its on the bottom near the junction of the differential and the main body of the tranny.

I'll check the 89' tonight. I won't have the 88' transmission for another week. It's being shipped from Texas.