quattro in reverse?

I've often wondered, does the quattro work in reverse? I.E. does quattro give me better traction when backing up on snow or ice?
(Yes, I know ... I do have too much time on my hands.)
Thanks, Bob
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Yes.
Yes. -- C.R. Krieger (Been there; done that)
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But the heart of quattro in all Audi's except for the TT is a Torsen differential which is purely mechanical. No wet plate clutches in it.
On Tue, 20 Jan 2004 11:22:15 -0600, "C.R. Krieger"

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wrote:

Is there even such a thing as a uni-directional differential?
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daytripper wrote:

No, but there are all-wheel drive systems that use electronically controlled clutches instead of differentials, and I'd imagine that these might not operate in reverse. It could be that the OP doesn't know or understand the difference.
-- Mike Smith
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Exhaust pipes at the back, and the seat with the round hand-rail faces the front?
;o)
(Semi-non-facetious bit: like brakes, clutches only operate in one rotational and one linear dimension. Direction is irrelevant, just the outcome. A bit like a politician.. ;o)
--

Hairy One Kenobi

Disclaimer: the opinions expressed in this opinion do not necessarily
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Hairy One Kenobi wrote:

Yes, but that's only *if* the clutch engages. Given that they're electronically controlled in such systems, the electronics could easily be programmed not to engage the clutch while in reverse.
-- Mike Smith
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But /why/ would someone do that..? Why would a rational engineer increase the cost of a product in order to reduce the performance, efficiency and safety?
It makes no sense.
H1K
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Hairy One Kenobi wrote:

What makes it cost more to disable the clutch operation? It's all software anyway. It probably looks something like this (just a wild-ass-guess example):
if (wheelslip > THRESHOLD) {     if (speed < CUTOFF)         engage_clutch(MODE_ONE);     else         engage_clutch(MODE_TWO); }
...uh, or something. If they allowed operation in reverse, they might very well have to add more code, like this:
if ((wheelslip > THRESHOLD) or (wheelslip < REVERSE_THRESHOLD)) {     if ((speed < CUTOFF) and (speed > REVERSE_CUTOFF))         engage_clutch(MODE_ONE);     else         engage_clutch(MODE_TWO); }
That's a little bit more code that someone has to write, someone has to maintain, someone has to test, one more thing to screw up, etc. Maybe it's just simpler (and better for the bottom line) to disallow operation of the clutch pack while in reverse gear.
-- Mike Smith
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You've made my point, but then missed it. How about if you replace the code with:
<Absolutely nothing>
Which seems even easier to design, code, and maintain ;o)
H1K
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Hairy One Kenobi wrote:

Then how does the system determine when to engage?
-- Mike Smith
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Same as when moving forward - you just have to take the modulus of the speed (i.e. remove the +/- sign)
H1K
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yes quattro works in reverse , thats why they did not use the titan (vw) back in the 80s a viscous wouldnt work in reverse the electronic systems have no probs working in reverse and my a4 a6 and a8 /v8 all work 4wd in reverse

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ee <ee> coughed up the following:

And just to chime in with the obvious----it would be absolutely HORRID if it didn't!
Having a 2 wheel car when you're trying to back out of a snow covered ditch?
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