ABS and Audi's "Antilock Off" Switch
laraa at sympatico.ca
laraa at sympatico.ca
Fri Feb 1 19:49:45 PST 2013
By the way, ABS or not, if you encounter a skidding event while braking,
your first job is to find a more appropriate braking surface.
Last week, there was a perfect day for black ice : very cold, -18C, about
half an inch of fresh powder, sunny sky. The perfect combination for black
ice at every stop or traffic light in Montreal.
So I left home at 4PM to pick up the girls at school, since I work from home
it was my first outing of the day. I noticed that the street was kinda
shinny. Very shinny. I tested the brakes : no grip at all. So I moved the
car to the right to grab a bit of packed snow and I managed to stop the car
before the intersection. Then I parked the car just the other side of the
street and went out for the school.
Then I heard that awful sound : the sound a car makes when it hits the rear
bumper of school bus. They were exactly where I steered the car to the
packed snow on the side of the street... Someone didn't notice the black ice
and didn't look for an alternative. She was lucky not to eat that big black
bumper, since she was driving a Civic and the a-pillar was badly bent by the
So my point is : ABS or not, good tires or not, one should always look for a
place to skip an accident. And that is one thing you must practice
regularly. Test the brakes when in doubt. Move the car out of the normal
line to see how much grip is available. If the traction control light is
blinking while accelerating, you'll have the same difficulty stopping.
And never follow the two ruts blindly...
De : quattro-bounces at audifans.com [mailto:quattro-bounces at audifans.com] De
la part de Mark Rosenkrantz
Envoyé : 1 février 2013 18:47
À : vittorio at mybares.com
Cc : quattro at audifans.com
Objet : Re: ABS and Audi's "Antilock Off" Switch
Thanks, Vittorio. But I know you meant to say, "DECREASES" your stopping
I knew the subject car was older because it HAD an ABS off switch. Older
cars pulse infrequently... as the wheel turns, I describe it as stopping
motion every thirty degress (or larger in first gen)... IE big "chunks."
Newer ABS systems pulse VERY quickly (some more than once per degree of
revolution)... in other words, you can't even see it happening when looking
at the wheel- only hear and feel it.
On Fri, Feb 1, 2013 at 6:27 PM, <vittorio at mybares.com> wrote:
> +1 on Mark's description.
> The purpose of ABS is to maintain control of the vehicle by
> maintaining wheel rotation.
> If you want to increase your stopping distances, make sure you have
> the most appropriate tire for conditions - i.e. A good winter tire can
> increase your stopping distance by up to %50 vs. all season, even if
> the road is pavement, but the conditions are close to the freezing mark or
> -------- Original Message --------
> Subject: Re: ABS and Audi's "Antilock Off" Switch
> From: Mark Rosenkrantz <speedracer.mark at gmail.com>
> Date: Fri, February 01, 2013 5:40 pm
> To: "mboucher70 hotmail.com" <mboucher70 at hotmail.com>
> Cc: quattro at audifans.com
> I've been instructing for Audi at winter driving schools since 1999 or
> 2000. ABS engagement IS wheel lock-up. Threshold ABS usually can
> shorten pure ABS stopping distances. For most drivers without
> significant training (and yes, I include enthusiasts and people with
> some track days) on snow, full ABS is the way to go, especially on
> newer cars. Pre-2000 (1980's and 1990's vintage) the ABS was pretty
> bad. Better than not having it, but newer systems are quite good.
> Here's the scoop:
> 1. There is one (and only one) condition where disabling ABS (allowing
> the wheels to fully lock up) will shorten the distance. That is with a
> slippery substrate (bottom surface), such as ice, with snow on top. A
> locked-up tire in these conditions will act as a "plow" and build up
> snow in front of the tire, shortening the distance. You give up all
> ability to steer, however.
> 2. Don't confuse disabling ABS with disabling ASR (anti-slip
> regulation which controls wheelspin) or anti-skid control (those
> squiggly lines on the icon). Those are integrated and I could add into
> the discussion if some desire.
> 3. If a wheel is locked up, you can't turn. You must control, IN ORDER:
> A. Wheelspin/wheel lock up
> B. Understeer
> C. Oversteer
> D. Counterskid (from oversteer correction)
> I can't stress enough that the newer the car, the better these systems
> are. For almost every single driver and situation, it IS better to
> leave these systems engaged. There are a few exceptions, and then only
> for formally trained drivers READY to react instantaneously. I keep my
> systems engaged on the street.
> Hope I've helped!!!!
> Mark Rosenkrantz
> On Thu, Jan 31, 2013 at 10:13 PM, mboucher70 hotmail.com <
> mboucher70 at hotmail.com> wrote:
> > In December, during a highway drive from Toronto to Montreal,
> > weather turned quite bad. At some point we were brought to
> > stop-and-go traffic, perhaps between 0 and 20 km/h. At one point
> > when we needed to stop, it turned out that we were on black ice
> > hidden by blowing snow. The ABS kicked in, and it seemed as though
> > wed sail straight into the car in
> > of us! I kept solid pressure on the pedal, and we JUST managed to
> > stop, probably within a few inches of the car in front. If we hadn't
> > stopped,
> > wouldn't have been much more than a harsh bump. Nonetheless, its a
> > bad feeling!
> > I'd had similar (though not nearly as bad) experiences in the past,
> > but still never disengaged the ABS because all of the studies I'd
> > read had
> > the case that ABS could save your life if you locked up the tires at
> > high speed.
> > After this near miss, Id had it with the ABS. I immediately put the
> > car in park, pressed the "Antilock Off" switch, and continued the
> > drive. It felt so much more in control, at low speeds, even if I was
> > locking them
> > at times.
> > Question I've been pondering is what's to be concluded from this
> > about
> > "Antilock Off" feature that used to be available:
> > 1.) It was useful in situations such as that above, but since the
> > overall benefits of ABS outweighed the downsides, it just became a
> > standard
> > feature and Antilock Off" switches disappeared.
> > 2.) ABS has significantly improved from designs used around the 1990
> > vintage, to make the need to disable them obsolete.
> > 3.) The Antilock Off switch was a useful feature and would be nice
> > to have in current-day production cars.
> > Other thoughts?
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