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Locked differential driving
SNOW/ICE driving
So... How can you steer on snow with the rear diff locked? I don't autocross
at all, but when I lock both diffs in snow/ice, it's really difficult to
steer. I don't think locking the rear diff is a good on_road technique (is it)?
Am I missing something?
Well, I drive with a tail-out rally type style. With just
the rear diff locked, I start the turn with the wheel and
then control and complete the turn by steering with the
throttle. By modulating the throttle I control the amount
of rear-wheel wheelspin and hence the radius of the turn.
This is NOT for the novice and should not be used in
traffic, etc.
Since I have a 5000TQ, locking any diff causes the ABS to
disengage. So, I usually ride around in slippery weather
with the diffs unlocked. On *real* slippery surfaces there
isn't much throttle steer available making the car kind of
unstable (my biggest quattro complaint). The car just seems
to pivot right in the middle without any tendancy for
stability with more or less throttle.
That's part of the reason why you need to be able to lock
just the rear diff. You want to be able to break both rear
wheels loose, to steer with the throttle, without breaking
the front wheels loose and loosing steering response.
With both diffs locked, when you break the rear tires loose
you also break at least one front tire loose and loose all
steering control.
It would be pretty easy to make the diff locks work separately; I think I'll
add a vaccuum switch to allow rear only lock, and try it out next winter...
..bill
I've got mine rigged so I can lock just the center, for
highway use in rain and snow, and just the rear for
"off-road" rally-style driving. I have non-ABS equipped
cars so I don't have to worry about loss of ABS when locked,
I don't got it at all!
-glen
=============================================================================
From: US1RMC::"GPOWELL@rimail.interlan.com" "POWELL, GLEN" 23-JUL-1993 08:59:53.3
1
To: Eliot Lim <eliot@lanmola.engr.washington.edu>, quattro@aries.East.Sun.COM (Qu
attro mailing list)
CC:
Subj: Re: sway bars counterpoint
"Scrub" is not really that much of a problem. I was
concerned at first about this, but it just doesn't
seem to metter that much (IMFO). The only time scrub can
even be felt is when the start has a very sharp turn
into the timer. When you get a setup like this you
can feel the scrub because you are still going very
slowly and turning very sharp at the same time. Once
you get rolling the scrub effect pretty much disappears
even in the sharpest of corners. This might bother other
drivers more that me, you know, those "precision" types
of drivers.....
I tend to drive with a "rally-type" style, using power
and the locked diffs to toss the rear end around and
eliminate the otherwise inherent understeer of the driven
front wheels. Running with locked diffs also creates a
very effective if primitive form of ABS. You lock one
wheel, you gottah lock at least three. It's real hard
to lock three wheels.
Locking the rear diff seems to be the most critical, so
I usually just lock 'em both. This seems to work equally
well with the Turbo Coupe and the 4000 Quattro. I think
the effect is more noticable with the 4000Q due to the
additional body roll and the much smaller sneakers,
205-55-14 on 6" wheels vs 215-50-15 on 8" wheels, even
though the TQC has almost 2x HP. It could also be due to
much more seat time in the 4000Q, perhaps 10+ auto-xs
vs only 4x in the TQC, and the TQC auto-xs were like
2-3 years ago too, memory fading and all.
I've got my Winter Beater (Tm) '84 4000Q setup so that
I can lock just the center diff, or just the rear diff.
Rear diff only is definitely the HOT SETUP for rally-
style hang-the-rear-out-at-WFO-style turns. *EXCELLENT*
in the snow and ice where these cars have so much # $%@#!#
traction that they can actually be boring. :)
Rear diff only locked + snow = boring !NOT!
Please try to keep all this good stuff of the auto-x
mailing list for obvious reasons. This is for fellow
Quattro enthusiasts ONLY.
Thanks,
-glen
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% From: "POWELL, GLEN" <GPOWELL@rimail.interlan.com>
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% To: Eliot Lim <eliot@lanmola.engr.washington.edu>, quattro@aries.East.Sun.COM (
Quattro mailing list
% Subject: Re: sway bars counterpoint
From: US1RMC::"GPOWELL@rimail.interlan.com" "POWELL, GLEN" 23-JUL-1993 08:59:53.3
1
To: Eliot Lim <eliot@lanmola.engr.washington.edu>, quattro@aries.East.Sun.COM (Qu
attro mailing list)
CC:
Subj: Re: sway bars counterpoint
"Scrub" is not really that much of a problem. I was
concerned at first about this, but it just doesn't
seem to metter that much (IMFO). The only time scrub can
even be felt is when the start has a very sharp turn
into the timer. When you get a setup like this you
can feel the scrub because you are still going very
slowly and turning very sharp at the same time. Once
you get rolling the scrub effect pretty much disappears
even in the sharpest of corners. This might bother other
drivers more that me, you know, those "precision" types
of drivers.....
I tend to drive with a "rally-type" style, using power
and the locked diffs to toss the rear end around and
eliminate the otherwise inherent understeer of the driven
front wheels. Running with locked diffs also creates a
very effective if primitive form of ABS. You lock one
wheel, you gottah lock at least three. It's real hard
to lock three wheels.
Locking the rear diff seems to be the most critical, so
I usually just lock 'em both. This seems to work equally
well with the Turbo Coupe and the 4000 Quattro. I think
the effect is more noticable with the 4000Q due to the
additional body roll and the much smaller sneakers,
205-55-14 on 6" wheels vs 215-50-15 on 8" wheels, even
though the TQC has almost 2x HP. It could also be due to
much more seat time in the 4000Q, perhaps 10+ auto-xs
vs only 4x in the TQC, and the TQC auto-xs were like
2-3 years ago too, memory fading and all.
I've got my Winter Beater (Tm) '84 4000Q setup so that
I can lock just the center diff, or just the rear diff.
Rear diff only is definitely the HOT SETUP for rally-
style hang-the-rear-out-at-WFO-style turns. *EXCELLENT*
in the snow and ice where these cars have so much # $%@#!#
traction that they can actually be boring. :)
Rear diff only locked + snow = boring !NOT!
Please try to keep all this good stuff of the auto-x
mailing list for obvious reasons. This is for fellow
Quattro enthusiasts ONLY.
Thanks,
-glen