May try shoving a 6HP26A into the car...

[nitrorocket]

The big question is, do I have to change the rear differential or not?

[mrdave]

Obviously, if I cannot figure out the wiring, or the gear ratio, the potential project would be dead. Oh those are the important things I need to find right now

Contact this guy about the TCU, he's super knowledgeable about that stuff: http://www.audizine.com/forum/member...243-ddillenger or http://nefariousmotorsports.com/foru...profile;u=4744

[kday]

Im planning on wiring in the newer tcu, ditching the old one. I need to see the wiring schematics, my hope is that it's mainly decision based off of the input sensors from the speed sensor and engine speed/ tps.

Unfortunately I think you are going to be disappointed here. The TCU is a computer and it's operated by software. You aren't going to be able to "rewire" a newer TCU to talk to an older ECU. There's a (remote) possibility that it will just work, but if so it will be because the software in the newer TCU talks the same "language" over the CAN bus as the older one does.

Edit to expand on this: the TCU, which operates the valve body, doesn't have a direct connection to the throttle position sensor and some other sensors it needs to operate. It receives messages over the internal computer network (the powertrain CAN bus) which are produced by the Motronic ECU, and these messages contain the throttle position (or, more likely, something like a torque request value which is the output of the "model" the ECU builds of what the driver wants to do). The TCU also sends messages back to the ECU and other modules like the ABS computer. This is why just replacing the automatic transmission with a manual box results in a check engine light and disabled ABS -- the other computers in the car are expecting the TCU to send certain messages and they go into fault mode if the messages don't arrive.

[nitrorocket]

No ABS would be a blessing! Lol

[Bigglezworth]

Good price...

http://m.ebay.com/itm/121219671378?nav=SEARCH

There is NO way that unit is bolting up to the C5 RS6 engine. The centerline of the front diff on this one is clearly further forward and almost past the mounting flange to the engine. The 5hp24 is significantly further back. This excercise is about more than just adapting a bellhousing, gearing, and TCU. Itabout physical alignmenet of the front drive axles within the chassis AND, ensuring sufficient space within the transmission tunnel to locate the two turbos. Massive bellhousing that has the TC located further towards the rear is even larger than the C5 and robs the necessary space for turbos and downpipes. WAY too much Frankensteining for even the most seasoned backyard autohead.

[nitrorocket]

But doesn't the six speed manual fit into our cars? I'm pretty sure I saw that has been done. So that would mean the six speed manual and the six speed automatic should have the same centerlines. No?

[nitrorocket]

Does the RS4, with a manual and automatic transmission?

[nitrorocket]

Here is one out of a phaeton.

[nitrorocket]

So it appears that the RS4 and the phaeton might have the same transmission, and the a8 is different.

[JSRS6]

I think you are on to something. Phaeton/rs4 trans looks more like 5hp in ours.

[SteveKen]

But doesn't the six speed manual fit into our cars? I'm pretty sure I saw that has been done. So that would mean the six speed manual and the six speed automatic should have the same centerlines. No?

The 5/6 speed 01E fits but not naturally.

The block from the RS6 and the D2 A8 are exactly the same, but I'm pretty sure the upper oil pan/skirt is different since the D3 doesn't need turbo oil return lines. Therefore, I'm not sure if the bolt pattern between them is exact below say 4 to 8 o'clock.

Pictured here is a spacer from a W12 Phaeton overlayed on the RS6 block. I'd be happy with this bolt/attachment coverage even though there's not an easy way to get a bolt at 10 o'clock.


It looks like there is conflicting information on what the transmission looks like or if there are different variations? The eBay one seems to be verified from a D3 A8 and confirms what I've heard, which is that the front diff is farther forward and would throw off the geometry of the front axles and interfere with the passenger side exhaust manifold among other things. Although, it looks like there's a spacer that is needed. See the pics of the engine that the eBay transmission came from (http://www.ebay.com/itm/2005-AUDI-A8...item19e8853256). Maybe it will bolt and actually work from a mechanical standpoint???

Electronic standpoint. I have no idea. If my S6/RS6 project was finished, I'd consider buying a D3 and sell you the transmission and all the guts and try to put an 01E in it.

[TozoM8]

That will be nearly impossible. Aside of the physical dimension differences, the 6HP26 has the TCU inside the trans.

[mik15]

plus you would need 6hp32, the 26 wouldn't be able to cope with the high torque, it's only rated for 550NM i believe, while the 6hp32 is 750NM rated...or even better the 6hp34 to make sure you get a higher range of torque limit.

[nitrorocket]

Tozo, it still apears to be comtrolled by a tcu in the phaeton. Here is a pic, looks just like the rs6 tcu... Maybe there is a secondary controller inside the transmission, but it still appears to be controlled by the TCU and as long as you get the harness going between the transmission and the TCU, it should function. Pretty sure I'm gonna find out.

Soooo, everyone says the 6hp26 is stronger than the 5hp. And im guessing if it will hold behind the 2008-2010 RS6, it will be fine in hours.

If anybody can help me lineup a wiring schematic for the phaeton and the RS6, ill tell you if it will work. I do a lot of custom rewiring of different cars, im hoping to figure this one out too. Theoretically I can always just use a standalone control module with inputs from the engine.

[nitrorocket]

If I can get the wiring schematics, I would really rather try to run it off the stock audi system with an integrated TCU from a phaeton,

Otherwise there are other options that will work to.

http://m.summitracing.com/parts/msd-...FXNo7AodpGwAzQ

[SteveKen]

That will be nearly impossible. Aside of the physical dimension differences, the 6HP26 has the TCU inside the trans.

I'm glad you chimed in on this, as I remember talking to you about this a couple years ago.

Do you know what kind of transmission is pictured strapped to the jack?

Also do you have any leads on any S8s with bad transmissions?

[hahnmgh63]

The bad news on the Phaeton is that the W12 came with the 5HP24, the 4.2 normally aspirated came with the 6HP19 or 6HP26A which would be the closest fit for us but like Mik15 said, it would never handle the Torque. And as it would be nice to have the 6spd, who wants to install a weak transmission that's going to fail like the 5HP after all of the work to convert.
6HP19 (strongest version, up to 450NM of TQ)
6HP26 (strongest version, up to 650NM of TQ)
6HP32 (strongest version, up to 750NM of TQ)
I left out the 6HP28 as their isn't a AWD version.
http://www.zf.com/media/media/docume...21_Catalog.pdf
http://www.zf.com/media/media/docume...28_Catalog.pdf
http://www.apra-europe.org/dateien/d...chatronics.pdf

[nitrorocket]

The 6hp26a also came in the 2008-2010 RS6. That made plenty of power!