ABS and Audi's "Antilock Off" Switch

Mark Rosenkrantz speedracer.mark at gmail.com
Fri Feb 1 15:46:49 PST 2013

Thanks, Vittorio.  But I know you meant to say, "DECREASES" your stopping
distances.... ;-)

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.

Mark Rosenkrantz

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 below.
> V-
>  -------- 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 we’d sail straight into the car in
> front
> > 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,
> it
> > wouldn't have been much more than a harsh bump. Nonetheless, it’s 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
> made
> > the case that ABS could save your life if you locked up the tires at high
> > speed.
> >
> > After this near miss, I’d 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
> up
> > at times.
> >
> > Question I've been pondering is what's to be concluded from this about
> the
> > "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
> safety
> > 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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