2001 a4 2.8 trans in a 2002 s4

[Sworddylan]

Hello all, I am looking for an answer as to if I will be able to use an auto transmission from a 2001 a4 2.8 in a 2002 s4? I have done research but have yet to find anything with these specific circumstances. I have heard you can use transmissions from different model cars as long as you use the tcm out of the car the trans is out of. I have seen there was a Speedo sensor change but that seems to be around 1999 and 2000 so seems irrelevant to this situation. Any insight would be great! I bought a 2002 s4 and it needs a new transmission, all I can find local is ones out of 2.8 cars. And one 4.2 car. Thanks!

[Bordom]

Not too familiar with auto-tragics, but I think they're the same transmission with the same ratios, but different programming.

Or is it that auto A4 have 4.11 ratios and the auto S4 have 3.50 something ratios? Someone with more knowledge will chime in

Everything graciously mispelled by Android

[a4kamila6]

I also wonder if the rear diff is slightly different

[Sworddylan]

I could swap that too if I need to. Still way cheaper than finding a trans out of an s4

[Cgoon009]

Just got some info on this from Walky. The rear diff in a manual 6spd is 4.11 with 108mm flanges. The rear diff in a tiptronic 2.8 is 4.11 with 100mm flanges. as for the actual trans, here you go:

http://www.audizine.com/forum/showth...c-Info-and-FAQ

[Sworddylan]

that helps somewhat. Anyone know what final drive the auto s4 is?

[mauromj]

Where are you at in Idaho? I have 2 tiptonics I am trying to get rid of.

[Sworddylan]

Boise area.

[Sworddylan]

Is there a better place to post this question?

[getslideways]

It is my understanding that the Auto S4 is 3.51 final drive (while the manuals got the 4.11)

[Sworddylan]

Hmm so I'd need the diff too. Easy enough just wish I could find a solid answer

[Bordom]

I remember there was an argument about this a couple months ago. I was involved lol.

[Sworddylan]

Do you recall if any solid answers came up?

[Nollywood]

It will work. But using the S4's TCU may cause erratic shifts. I have experienced this with a 2003 C5 2.7T with a C5 2.8 tip, using the original 2.7T TCU.

It never drove right after the swap.

[Sworddylan]

I have heard of using the tcm from the donor car. Which I can also get. But I am wondering if the plugs and everything are the same

[Nollywood]

I have heard of using the tcm from the donor car. Which I can also get. But I am wondering if the plugs and everything are the same

The plugs will be the same, as long as it's from a similar year chassis.

The 2.8 TCU file is very different to that of the S4. It will respond differently to load and rpm signals from the S4's ECU sufficiently to produce a drive that you wouldn't like. It will feel like a different car, and probably slip the trans into limp mode.

[Sworddylan]

That is what I had wondered. So from the rounds of it. It wouldnwork, ie, swapping the trans and diff but it may shift weird with using the 2.7 ecu

[MacDaddy]

It may be shifting adaptations that cause the issue swapping tcu's, I know for BMW's (also ZF) if the trans is rebuilt or replaced the tcu's needs reset and can only be done with the GT1, the 30-second stomp reset is only for driver preference reset (learns your driving style, aggressive or shift and changes shifting style accordingly)

Anyway, I know there is an early and late style transmission connector difference, but should be easy enough to swap the harness going from the solenoids to the outside (replace those o rigs while your swapping or your plug will leak)

Also check the green tag on the side of the trans, if they have the same model number your good to go (it's towards the back on the drivers side iirc)

[Sworddylan]

They are the came model. Just different codes