A8 trans swap - 5hp19
 

Hi guys,
I recently bought a really nice '00 40V A8 4.2L
and I am looking to put it in a mid-engine space frame with a 2.8 a6 FWD Auto transmission.
I've been told it's a bad idea but want to do it anyway because my options are limited and this specific build needs an auto. I can't find any info online related to this swap but I want to know basically how different the wiring and computers are. The ecu's look exactly the same to me, can the a8 ecu be used? Do I need the wiring harness from the a6?
I was hoping someone here might know because there isn't one person on the several American audi forums that does.
I have yet to start tearing the A8 apart.

So basically 5hp24 to 5hp19, any idea?

Transmission swap
 

I think they use the 5hp19 on the 3.7 a8 but I might be wrong...maybe someone could confirm that for you...

In short I don't see why not but not sure if the ecus will be compatible...

Use original 4WD gearbox just weld up centre diff and blank out rear otput.

Oh forgot to mention the 4wd is very long it'd be sticking out of the back of the chassis :(

Yes they do use the 5HP19A on the 3.7 as I've swapped mine!!

AWD though? or maybe it doesn't matter... mine would be the 5hp19FLA fwd version
so hopefully the newer 2000 4.2L A8 is similar electronically
I just wanted to be sure before tearing the car apart :\

Architex did your trans need to be replaced or something? I was looking for aftermarket parts to make it stronger since the 4.2 probably has even more torque. Not exactly familiar with what parts are weak, though.

Hi Tallon,

I have a similar idea for a project and all you need to do is get the TCU to match your transmission. Yes you 40V 4.2 has more torque but if it's from an A8 its not that much more, so a 2.8 FWD tranny should be able to cope, especially if your target vehicle is a lot lighter.

Yes the fourth gear started slipping after the MAF sensor had gone wrong so important to do a scan and check that too regularly. Box failed at 122k miles and the thread about it is HERE

thanks guys for the info

someone else told me I should be good in a light car as well which makes me feel a little better about it, I'm going to try to not add too much weight as I'm still working on the chassis. I think I'm going to get the upgraded D Drum since it's the piece that is always breaking for others. I wish there were more upgraded aftermarket parts. It seems I'll never be able to increase power of my car with this trans.


this is the aftermarket part they're saying is stronger
http://www.youtube.com/watch?v=L3fD-lYHpdA&feature=plcp
reverse d drum brakes where it's holding snap ring and clutch pack. Does this affect other gears or just reverse? I don't see where else is an issue as far as it being weak.