Lockable Rear Differential Info for the S2, RS2, 92-94 UrS4 and 95 UrS6.

[UrS4boy]

NP. I figured The Librarian must have missed those.

Why yes he did. As soon as I get up from the computer I will spin around and kick is @ss.

Added this:

"Here are some great Shift Lock Coupling photos courtesy of 4WheelDrifter on this forum:

Unlocked Position (from the front of the car looking to the back):



Locked Position(from the front of the car looking to the back):


"

[speeding-g60]

also check what happens when you launch >600 AWHP car with the diff not ENTIRELY engaged. i run mine permanently locked all the time, with the center diff locked (welded) as well. this was not fun as we had to get the car on 4 wheel dollies to tow it off the track

[afterburner]

Is the diff lock module of the B4 sedans also under the rear seat?

[Zoig]

My 09.1994 built UrS6 didn't have the mechanical diff lock, only EDL. Later I added the lock and whilst creating the harness I left the speed signal wire out alltogether. Just to be sure I created extra warning lamp in the cluster, it is wired in paralell to the green lamp. I located the warning lamp under the "ASR" (now called "Automated System Recovery" when i get stuck )

Testing of the harness, the cluster warning light is in the background.

[UrS4boy]

Is the diff lock module of the B4 sedans also under the rear seat?

Based on my friend Kate, she says yes (B4 illustration 919-98) But only one way to tell for sure. Remove the B4 rear seat and look for the silver controller box like this one:

[UrS4boy]

My 09.1994 built UrS6 didn't have the mechanical diff lock, only EDL. Later I added the lock and whilst creating the harness I left the speed signal wire out alltogether.

Zoig: Hmmm.....09/94 = 1995 model year. I *had* understood that EDL (no mechanical lock, just the ABS systems controlling rear wheel spin by applying the brakes to the spinning wheel) was a 1996 model year "feature". When you say you added the mechanical diff lock, what did you add? A complete mechanical diff lock rear differential or ???

[Zoig]

Zoig: Hmmm.....09/94 = 1995 model year. I *had* understood that EDL (no mechanical lock, just the ABS systems controlling rear wheel spin by applying the brakes to the spinning wheel) was a 1996 model year "feature". When you say you added the mechanical diff lock, what did you add? A complete mechanical diff lock rear differential or ???

Yes, only had the ABS controlled lock system from factory. I added full system from UrS4, all the vac lines to the rear seat, wiring harness (bit modified as explained), the switching box and the diff with lock.
The lock is also not connected to ABS, so i can run with EDL and rear lock if needed.

BTW, my old 1993 80 Avant FWD also had EDL on front wheels, no idea why someone ordered it instead of quattro.

[afterburner]

Based on my friend Kate, she says yes (B4 illustration 919-98) But only one way to tell for sure. Remove the B4 rear seat and look for the silver controller box like this one:

Yep! It was there and I just cut the speedo signal wire Now waiting for the winter

[UrS4boy]

Yep! It was there and I just cut the speedo signal wire Now waiting for the winter

If you take a photo of the B4 controller, I will add it to my rear diff lock post to make it more complete (with credit to you for the photo).

Dave F.

[afterburner]

I will take one later that week!

[malncol]

a bit off topic but what sort of hp will the diff locks take before they let go. looking at rally use ????
mal

[A80Avant]

I recently checked and my diff lock doesn't work.
Button lights up when pressed and the light was checked and does light up manually(when given appropriate voltage) but when it's supposed to work it doesn't. No ABS light comes up in the dash, and diff doesn't actually lock.

Is the diff ecu accessible through vagcom?

If I check all the appropriate lines, how can I test or make out if this is a diff module issue or something else?

Sent from my SM-P550 using Tapatalk

[newsh]

Check the little vacuum tubes under the back seat, there’s a one way valve and a T piece with rubber connectors that come off.
I think the engine bay vac line is the pink one, make sure it’s not leaking where it connects to the manifold.
Otherwise if the lock mechanism is getting vacuum then it might just be stuck and need freeing off.
I think you can get to the abs module in vagcom but I’ve never known one to go wrong.

[A80Avant]

vaccum leak found!
which also means that a boost leak is also sorted

[A80Avant]

also just to point out.
pink line comes directly from the engine. Should it be coming via the vacuum reservoir?