[s-cars] fact or fiction - diff lock relay...

[QSHIPQ at aol.com]

Varon:
I watched Dave Lawson try this B/W disable mod with his 90 200tq torsen wagon
a couple years ago at Bridgestone Steamboat Winter Track..  I don't think he
ever got the hang of it, and just put the rear diff back to auto disengage.
My own thinking is that the rear torsen is a better setup than the locker GIVEN
a center torsen.  My experience in snow/Ice with dual lockers is different,
as the Scandinavian Flick with a rear locker actually makes for a more
predictable swing and much more powerful tail out on throttle...
http://www.hometown.aol.com/qshipq/page1.html
  On tarmac tho, the rear diff locked up adds way to much understeer for my
taste (and it ripped my rear diff off my subframe on my 83 at Mid Ohio), so I'm
equipping my '84 RS2URQ conversion with the center locker and the rear
torsen, and will leave my 83 urq with  E-P dual lockers for comparo.

Don't worry about breaking the rear locker however.  Even the rally cars
couldn't break em.  IME, they can make other parts of the car/driver fail
however....  One of the main reasons audi made the Gen III an auto disengage.  It's
been a while since I installed 2 of the E-P boxes in my urq, but I believe you
could use an existing box feed, so that the blue/white needs to be re/engaged
on every startup.  I retained that in my E-P locker switches (shut off car,
diffs lights deactivate).  I also joined the B/W from both boxes under the
shifter, figuring an <all shutdown> mode might be cool.  I haven't done anything
with them yet tho.

A better mod for you ice boys would be to put a microswitch on the shifter to
engage and disengage the rear diff on the fly.  The nice thing about those
E-P boxes is they are 12v hit = on then 12v hit off.  Kinda handy for those so
inclined....

HTH

Scott "torsen boy" Justusson
91 v8 center clutch/rear torsen
'84 RS2URQ Project center locker/rear torsen
'83 urq (E-P dual lockers)
'87 4runner turbo dual lockers





In a message dated 10/17/2003 8:01:59 PM Central Daylight Time,
vfugman at globaldialog.com writes:
Ken & all,

First just to clarify for new folks, only 92-95 cars have the push button
lockable rear diff.  The 95.5-97 cars have EDL (electronic differential
lock) which simulates a limited slip diff by applying the brakes to the
spinning wheel.

Normal behavior is for the diff to automatically unlock at around 15mph
(which is more like 24km/h).  Perfect for launching in snow and ice and
leaving all those "4x4" SUV's behind!

I too have been looking into disabling the 15mph disconnect for running ice
trials.  Of course, I'm not sure if this will be a good idea or not...
keeping the diff locked could cause some serious understeer (or other
handling anomalies) in turns... and the quattro is hard enough to drive on
ice as is.*

There is a wire feeding the diff lock controller under the back seat that
tells it when the "drop-out" speed has been reached.  IIRC it is white with
a blue stripe.  If you cut this wire (or put in a switch) I believe the diff
lock becomes full manual... and I would expect that it won't cut out by
itself at any speed until you hit the button again.

I'm hoping to try this first-hand this coming winter.  I might just splice
switch into the wire so I can try it both ways.  If I like having manual
mode available I might add a relay controlled by a button in the dash (along
with my ABS switch that I haven't finished installing yet!)

Why not just cut the wire and be done with it?  Because the only place I can
see wanting to keep the diff locked over 15mph (24km/h) would be for a
winter track or lake event.  For on-road use I want to keep the automatic
drop-out.  I think very bad things would happen keeping the diff locked on
dry or even partially dry pavement (tire wear, handling problems, possible
drive-train damage).

Varon
'95 urS6 waiting for ABS switch and diff lock manual mode

*The quattro system is fantastic for on-road winter driving... a regular
snowmobile.  Whatever traction is available it will find it and use it.  But
get out on a frozen lake where there is almost zero traction and the torsen
center diff seems to "hunt" making for unpredictable handling... applying
throttle in a turn seems to produce understeer 2/3 the time and oversteer
1/3 the time.  Almost makes me want my old predictable FWD ice trials car
back!

-----Original Message-----
From: s-car-list-admin at audifans.com
[mailto:s-car-list-admin at audifans.com]On Behalf Of Ken Ng
Sent: Friday, October 17, 2003 3:57 PM
To: s-car-list at audifans.com
Subject: [s-cars] fact or fiction - diff lock relay...


I understand that the 92-95.5 UrS cars have a push
button lockable rear diff. and that the locking
feature is electronically 'unlocked' at ~40km/h - i
spoke to a fellow 95.5 UrS6 owner and he indicated
that there is a relay that can be removed to
deactivate the auto 'unlock' at ~40km/h... and that
somehow this permits full lock up to 100km/h...

query: 1. is this fact or fiction, 2. what happens at
100km/h that causes it to 'unlock' when the relay (if
such a thing exists) is removed and 3. what are the
adv. and disadv. of removing the relay ...

TIA,
Ken