Pete

"Not James" <NotDisclosed@nospam.com> wrote in message
news:T%Ccb.14366$gv5.4212@fed1read05...
> My error. I meant to state that I was inquiring about the Quattro in the
A6
> 4.2.
>
> Does this make a difference? Is it managed in the same manner as the TT?

No, the quattro in the A6 is the torsen system (full time AWD). The quattro
in the TT is the haldex system.

Cheers,

Pete

Peter Bell

In message <d7j5nvcb843pd4ke6efl30ftcepd7cqh1i@4ax.com>
Jim <jim@none.no> wrote:

> Related Quattro question: My 2001 A4 (1.8t, Tip, Quattro) got stuck
> in the snow twice during last years eastern snow storms. The snow was
> fairly deep with an icy layer under the snow. A push got me going,
> but while I was stuck, only the rear wheels were turning / spinning.
> Is my Quattro bad (no known driving or handling issues) or is it
> normal for only the rears to spin during certain situations?

In theory, no. With the rear wheels unloaded (as in not having any
grip) the Torsen centre differential should have transfered 75% of the
torque to the front wheels which should then have moved the car, or
started spinning themselves. A wheel on one side should be prevented
from spinning by the electronic differential lock function implemented
via the ABS system.

All this assumes that your car does have a Torsen centre diff, and open
front and rear axle diffs. I think that some of the automatic cars did
have a slightly different arrangement, relying more heavily on the
ABS/brakes for transfer of torque. If your car is one of these, then
your experience could point to an ABS problem.

--
Peter Bell - peter@bellfamily.org.uk

abcde@nexgo.de

Jim wrote:
> The snow was
> fairly deep with an icy layer under the snow.

> while I was stuck, only the rear wheels were turning / spinning.

> Is my Quattro bad (no known driving or handling issues) or is it
> normal for only the rears to spin during certain situations? Thanks.

I'm quiet unsure about what type of traction control a 2001 A4Q actually
has. I'm assuming here: TorSen center diff, open (manually) lockable
rear
diff. And: NO EDL's!

If it is TorSen, it is not able to split more than say 25/75. So: 0 grip
at one axle is 0 x 75 at the other end and that is: 0! Spinning tires.
In your case the solution would have been to apply "grip" to the
spinning
axle: use the handbrake to transfer torque to the rear output shaft of
the
TorSen. Then 75 x something = something for the front: You would have
been
rolling.

Unlucky if you have a front tire spinning: No lockable diff and no
*separate* brake for the fronts only either... So always point the
REAR to the more slippery patch on the ground!

Summary: That problem occurs, if the grip-difference between front and
rear is over a specific limit.

So long!
Ero.

P.S. If the car is equipped with EDL, that *should* have braked the
spinning wheel(s) to let the TorSen transfer some torque to the other
axle.

--
Ero Rademer ANTISPAM in effect.

Romy Singh

"jpb357" <jpbspam357@juno.com> wrote in message
news:3f72f61f$0$43880$a0465688@nnrp.fuse.net...
> My first Quattro was also an '01 A4 1.8tQTip and I never had such a
problem
> in that car or my current A6 2.7tQTip. It comes to mind that perhaps the
> snow buildup had "lifted" the chassis so that the tires were no longer in
> firm contact with the roadway and a push was all that was needed to get
you
> over the hump.
>

That's possible, but on two occasions I found my car to act differently than
I had expected. First one was in the snow, I can do a spin-a-roony if I
really want to, the wheels do slip, even when starting from a standstill.
But that was no biggie, more concerning is the next case. My A4Q went off
the road once, into a ditch. Three wheels were firmly planted on the (hard)
ground, while the fourth didn't have as much weight on it, that wheel kept
on spinning, no matter what.

I thought with the Quattro system, even if only one wheel had grip, it would
be enough to move the car, not too sure I believe that anymore...


Romy

JP Roberts

Totally agree on the spin-a-roony, which I've also done on both snow and
fine gravel. I can't tell you about any "ditch" situation as you depicted,
but I suspect the EDS, i.e., the braking of the wheels is only effective up
until a certain amount of torque. If that threshold is exceeded on a
low-grip surface the wheels will slip-spin, no matter what.

So, the golden rule of smooth and very gentle acceleration prevails when
pulling out of slippery surfaces, I guess.

By the same token, I would hazard an engine with a comparatively low
torque - say an 1.8T, might in good hands do better than a mightier one,
because it's easier to apply just only the necessary torque so that the
wheels won't lose grip.

These are only assumptions but they're based on my experience. I would be
curious to know which the torque values are that have been used in
pre-programming the quattro-brake-assisted system.

My two cents,

JP


"Romy Singh" <cool5abi@hotmail.com> escribió en el mensaje
news:7asdb.153364$DZ.75621@news04.bloor.is.net.cab le.rogers.com...
>
> "jpb357" <jpbspam357@juno.com> wrote in message
> news:3f72f61f$0$43880$a0465688@nnrp.fuse.net...
> > My first Quattro was also an '01 A4 1.8tQTip and I never had such a
> problem
> > in that car or my current A6 2.7tQTip. It comes to mind that perhaps
the
> > snow buildup had "lifted" the chassis so that the tires were no longer
in
> > firm contact with the roadway and a push was all that was needed to get
> you
> > over the hump.
> >
>
> That's possible, but on two occasions I found my car to act differently
than
> I had expected. First one was in the snow, I can do a spin-a-roony if I
> really want to, the wheels do slip, even when starting from a standstill.
> But that was no biggie, more concerning is the next case. My A4Q went off
> the road once, into a ditch. Three wheels were firmly planted on the
(hard)
> ground, while the fourth didn't have as much weight on it, that wheel kept
> on spinning, no matter what.
>
> I thought with the Quattro system, even if only one wheel had grip, it
would
> be enough to move the car, not too sure I believe that anymore...
>
>
> Romy
>
>