97 Quattro EDL's-what are they?

[dmiller@iea.com (Doug Miller)]

I am somewhat embarassed to admit that I don't know much about the Quattro
system on my 97 A6 Wagon. There really was no question what I was going to
buy, and I tried to find as much information about the current Quattro
generation before I bought out of intense interest, rather than for a
buy/don't buy decision.  Frustratingly, the dealership people were
incredibly ill informed about it, and my Quattro driving brothers (3 of
them) weren't sure, either - a  genuine rarity.

I know all about the previous generations with their locking diffs (my
preference is for these driver controllable units), and I have factory
locking front, center and rear diffs on our 93 LandCruiser.

Here is what I know:  My car has a Gleason-Torsen center differential,
which I am familiar with.  The front drive A6's have an EDL (Electronic
Diff Lock) on their front axles.  There is some vague reference to an EDL
in my manual, but no information whether this is front only, front and
rear, or a mistaken reference to the FWD models.  Even the websites and the
page in the 97 brochures discussing the Quattro system are surprisingly
mute on this subject.

What I want to know is this:  Where are the EDL's on my Quattro (if any),
and how do they work?  Do they achieve full lockup? Are they dry clutches?
Wet clutch packs? How long do they tolerate wheelspin before locking up?
How long before they release? What speed ranges to they work? Can they
handle continuous wheelspin, or do they have a duty cycle?  If there are no
EDL's, what kind of diffs do I have on the axles?

I've had it for a couple weeks, and the other day I put the left front
wheel on an ice patch on my sloping driveway with the others on snow.  The
tire on ice was spinning happily away, while the others pushed me up the
driveway and there did not appear to be any effort to reduce the wheelspin
going on.  It was not uncontrolled wheelspin - seemed to be limited
slightly - but the wheelspin was not brought under control.  I was hoping
it might be stopped by an EDL clamping down or something.  At the very end
of the ice patch, I *thought* I felt some ABS-like buzzing. This was about
a 3 second long test and I had to quit as my wife came out to hop in and
head to the store (amazing how many errands you find to do with a new car).

Here in Idaho, we have an incredible amount of ice - rather like a
Scandanavian country I suppose.  We even run custom siped, studded tires on
the full time 4wd 'Cruiser for safety.  I have plenty of opportunities to
test that tasty Bosch 5th generation ABS, and the Quattro system.

Inquiring minds want to know.  Any input?

TIA

Doug Miller
dmiller@iea.com