2001 A4 Rear Diff Compatibility

[Ben830]

2001 A4 1.8t Manual 01A AWD

My daily has a whine in the rear end. Wheel bearings are the likely culprit but it could also be the diff or or or. I'm dropping it off with the tech this afternoon to diagnose it. In the event it is the diff I've been searching online to see which cars are compatible and I can't definitively find a list of what cars I could pull a diff from, should I need to.

So far it seems like I can grab a diff from 97-2004 manual 1.8t's and maybe b5 s4's but the info is all over the place.

Can someone please help me out or point me in the right direction.

[Ben830]

After 6hrs of googling I found this 18 year old post. lol

https://www.audizine.com/forum/showt...ntial-all-3-89

From your post, it seems like you swapped your Auto tranny for a manual version. In this case you should use the diff that was meant to go with your tranny.

Here's the rundown:

Audi A4 Manual 96-01:

CHK = 3.889
This diff was meant to pair with the following trannies:
CTF
CXF
CXW
DDL


DAJ = 3.889
This diff was meant to pair with the following trannies:
CTF
DJJ
DJP
DDL
DJR


Audi S4 Manual 00-02:

DQA = 4.11
Only meant to go with the 6-speed S4 tranny.


Audi A4 Automatic 96-01:

DAK = 4.11
DXT = 3.889

The DAK final drive has 100mm drive axle flanges, the DXT has 108mm drive axle flanges. You will need to get the rear axles with the diff otherwise, you won't be able to get power to the rear wheels.

And this 13 year old post

https://www.audizine.com/forum/showt...identification

5-speed manual
1.8T AWD O1A Transmission Codes; DJJ, CTF.

2.8L AWD O1A Transmission Codes; CXF, CXW, DJP, DJR, DDL.

5-Speed automatic
1.8T and 2.8L O1V AWD Transmission Codes; DDT, DRD, EBX, EFP, EKC, EZS, EZZ, DTV, DKB, EFQ, DRN, ECG, FAL, EKD, FAS, FHH. ( There are four other codes that are related to the euro 2.7T engines)

and this

[walky_talky20]

B5 A4 has a very long nose, while other Audi's (C5 A6, B6 A4, etc) are a more typical length differential

Short diff (C5, B6, etc):


LongBoi diff (B5 A4/S4):


Now, that long nose piece does come off, so I suppose you could probably use a B6/B7 diff of the correct ratio by swapping on your existing nose section, if you really needed to:


To get into more specifics: your North American B5 with 5-speed quattro gearbox definitely uses a 3.89:1 ratio with 100mm axle flanges and the long nose form factor.

For a direct fit
- a 1996-2001 B5 A4 (not VW Passat) with a 5-speed manual gearbox.
- *Maybe* a B4 (92-95) Audi 90 quattro. I think this would add a rear locker! Do your research if this interests you.

For a short diff that you could convert (maybe, do your research):
- B5 Passat 4-Motion (with 5-speed 01A only).
- B6 A4 with 02X 6-Speed or 01A 5-speed (not 01E 6-speed or Tiptronic, those are 4.11)
- B7 2.0T with 02X 6-speed

Things that will definitely not work:
- B5 S4. These are 4.11. All of them.
- B3 (88-91) 80/90 quattro or Coupe Quattro. These are 4.11
- C5 A6. These are 4.11
- B8 A4. These are a different thing altogether.
- D2 A8. These are 3.7 or 4.11
- D3 A8. These are a different thing altogether

[Ben830]

B5 A4 has a very long nose, while other Audi's...

Thanks so much for the reply.

[walky_talky20]

Thanks so much for the reply.

You are most welcome.

Questions about cross-millennium compatibility of classic Audi drivetrain parts are my favorite. 1988 B3 parts that fit on a 2008 B7 chassis? Ooh, that's *the stuff*.

[A4Qwattro]

For fun:

[walky_talky20]

If there's one thing I like more than cross-millenium compatibility discussions - it's Accurate High-Fidelity Drivetrain Cutaway Pictures.

This thread is just <breathes in deeply through nose>.... THE BEST.