Are the A4 Auto Rear diff and the S4 rear diff the same?

[Blake260]

Im doing research to swap my now tip 1.8T to a six speed, and have come across a very interesting bit of info. at first, I was planning on getting an S4 rear diff.

then I found this thread: http://www.audizine.com/forum/showthread.php/415035-Another-5-Speed-swap

which mentions the auto rear diff ratio being 4.11 (same as S4) as opposed to the manual A4's 3.89 ratio. Now, I can see swapping the rear diff if you were to replace the TIP tranny with a 5-speed, but with a 6-speed, I am hoping to use (and already Have) the 4.11 rear diff.

So, my basic question is:


Can anyone confirm that the 4.11 rear diff found in automatic A4's is the same 4.11 diff as the one found in manual S4's (identification code: DQA)?


If it is indeed the case, I could get away with keeping my rear diff and just swapping the driveshaft (in favor of the S4 driveshaft).


Thanks!

[FNK]

Yes, the 5 speed Tiptronic rear differential is the same as the 6 speed manual.
Also, the drive shafts are all the same. (96 where carbon fiber, but was the same weight (or very similar) and was replaced with steel).

[Blake260]

awww snap! thank you sir. that is awesome news!

[BKLenny]

Could you fit the 2.7T and 6-Speed manual into an A4 Avant? Anyone know if this has been done? I did some searching but only found one such swap into an A4 B6. I am gonna have to do an engine swap anyway, might be kind of cool to do an upgrade while I am at it... :D

[nate09]

Could you fit the 2.7T and 6-Speed manual into an A4 Avant? Anyone know if this has been done? I did some searching but only found one such swap into an A4 B6. I am gonna have to do an engine swap anyway, might be kind of cool to do an upgrade while I am at it... :D

I don't see why it shouldn't, fits in the sedan just fine.

[BKLenny]

I don't see why it shouldn't, fits in the sedan just fine.

This is exactly what I was thinking Nate.

[Blake260]

itll fit fine, but if you have a 1.8T, you'll need a 2.8 or S4 front subframe i believe

[BKLenny]

I currently have a 2.8 30V with Tiptronic.

[M-Hood]

itll fit fine, but if you have a 1.8T, you'll need a 2.8 or S4 front subframe i believe

That would be wrong. The B5 A4 1.8t Tip uses the same type of transmission mount on both sides just like the V6 cars. It is just the A4 1.8t Manual that has the different sub frame and different driver side mount.

As for the rear diff, I would suggest looking into what ratio the rear diff has based on the code/part number that is on it. Most info on the web shows the B5 1.8t automatic/tip to have a 3.73.

[walky_talky20]

^Mike, I found that to be the case as well. I have no idea why a lot of those B5 A4 specs sheets online have 3.73 gearing listed, but it is completely incorrect. The Bentley manual shows only 2 different ratios for the B5 A4/S4: 3.889 or 4.111. The 3.889 is for A4 5MTs and S4 Tiptronics. The 4.111 is for A4 Tiptronics and S4 6MTs. There are no expections to that rule that I could find.

In any case, it takes an entire 5 seconds to check the diff code in the trunk on the option sticker. DAK is the code for the 4.11's.

[Corrado_Guy]

There are 4 final drives used on the rear of the B5 which would be...
DAK & DQA: 4.11:1
DAJ: 3.89:1
CKK: 4.56:1
DRL: 3.70:1

The 01A uses...
DWM, DWR, EEP, ENP: 3.89:1
DWN: 4.11:1
DWQ: 4.56:1
DTT: 3.70:1

The 01E uses....
DQT, DSY, EHW, FTF, FRQ, FTK, FZV: 4.11:1

These are all taken from ETKA but I only have version 5 and 7 and both of which do not list the automatic final drive as a replaceable part. The best idea is to match your rear diff to the first list and then you will know what the automatic final drive is if you really wanted it. The Bentley manual is not really a good reference for a lot of this stuff as it tends to be a little generic and doesn't get updated as much. I use ELSA which is the factory manual used by dealerships and is updated more often and usually more accurate as a reference.

[nate09]

This is exactly what I was thinking Nate.

Are you getting your stuff from Norbs or A1?

I haven't had to go to either yet, there's another place I have been to but I can't think of the name now. If you're going to swap engines, might as well go big with the 4.2, it's what I'd do.

[BKLenny]

Yeah, the 4.2 would be sweet, but I had already sort of found a wrecked S4 for cheap. It has the 2.7T and 6 speed manual tranny. The intercooler is toast, but otherwise the crash didn't hurt the engine. If I can get it to drop right into my car, I am all there! I just gotta find someone that can do the work for me now... lol

[FNK]

1.8T and 2.8 TIP only, both use 4.111 as the final gear ratio. While the 2.7T TIP use 3.889.
The 2.7T manual use 4.111.

[BKLenny]

Yeah, I am pretty sure it will work.

[walky_talky20]

Yeah, that should be pretty plug and play if you have the entire car.

[Osher67]

Bringing back from the dead.... I have a rear diff from a auto 05 s4 (HHU)

And my car is 02 a4 5speed swapped to 01a out of a 2.8 b5 a4 with my orginal diff still. Never really gave thoyght to it but is the drive different that came with the 01a? Then the one that came with my car (2002 a4 5spd) ?
Was thinking if 01a is 4.111 was the same as the s4 diff I had or not. What do I look for on my trans to differentiate which 01a I have?
Are these swappable normally too? Or is it pretty specific to each ratio.
I'm still lost don't know if I should expect answer here on this old thread but thought I would start here (not start a new thread)

[M-Hood]

Bringing back from the dead.... I have a rear diff from a auto 05 s4 (HHU)

And my car is 02 a4 5speed swapped to 01a out of a 2.8 b5 a4 with my orginal diff still. Never really gave thoyght to it but is the drive different that came with the 01a? Then the one that came with my car (2002 a4 5spd) ?
Was thinking if 01a is 4.111 was the same as the s4 diff I had or not. What do I look for on my trans to differentiate which 01a I have?
Are these swappable normally too? Or is it pretty specific to each ratio.
I'm still lost don't know if I should expect answer here on this old thread but thought I would start here (not start a new thread)

The 01A 5 speeds in the B5 A4 1.8t, 2.8 and B6 A4 1.8t are 3.889 final, the only 4.11 01A 5 speed was found in the older Audi Coupe.

The B6 A4 1.8t 6 speed came with a 4.11 final drive.

[Osher67]

The 01A 5 speeds in the B5 A4 1.8t, 2.8 and B6 A4 1.8t are 3.889 final, the only 4.11 01A 5 speed was found in the older Audi Coupe.

The B6 A4 1.8t 6 speed came with a 4.11 final drive.

Ok that clears up a lot I've had the trans in the car for while now (not up and going yet) but had me thinking back recently if I may have missed something.

Another question though
Would you mess up a trans or diff if you ran a different one like a 4.11 diff in a 3.889 I don't know what would be the advantage but just curious if people mix and match lol.

Thanks for the swift reply mike


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[walky_talky20]

A 2002 B6 A4 5-speed quattro will have a 3.889:1 rear differntial. That will match up fine with your 5-speed transmission that you got from a B5 2.8 quattro.

The B6 S4 6-speed Tiptronic rear differential you have, however, is different. From documentation I could find, its ratio is 3.539:1.

You cannot mix and match. Because we have torsen center diffs (no clutch packs) it will actually work for a little while. But you would be working the small, high-friction worm gears and the friction washers excessively. It would overheat the center differential and wear it out or break it pretty quickly. I'd say if you mixed a 3.889 front and 4.11 rear, it would have problems in less than 50k miles. Probably excessive slop (clunks when getting on/off throttle) would be the first symptom and then noise from the bearings once enough metal ended up in the gear oil and trashed them all.

[Osher67]

A 2002 B6 A4 5-speed quattro will have a 3.889:1 rear differntial. That will match up fine with your 5-speed transmission that you got from a B5 2.8 quattro.

The B6 S4 6-speed Tiptronic rear differential you have, however, is different. From documentation I could find, its ratio is 3.539:1.

You cannot mix and match. Because we have torsen center diffs (no clutch packs) it will actually work for a little while. But you would be working the small, high-friction worm gears and the friction washers excessively. It would overheat the center differential and wear it out or break it pretty quickly. I'd say if you mixed a 3.889 front and 4.11 rear, it would have problems in less than 50k miles. Probably excessive slop (clunks when getting on/off throttle) would be the first symptom and then noise from the bearings once enough metal ended up in the gear oil and trashed them all.

Ahh I see that makes sence I have the washer/spacer mod in my center diff as well excited to see how that will feel still have a ways to go for rest of the car though. Thanks for clearing that up.