Hi YPW, All!

The ABS system, as someone here noted, is supposed to pulse the
brakes, rather than simply locking the wheel(s), as would be the case
in a foot-to-the-floor panic stop situation for most drivers. The ABS
on my pops newer Caddy does just this (I tried it out on an icy patch
when he first got it . . .). It really does help maintain control of
the car; you don't really _stop_ any faster, but you maintain steering
control for the most part. In a similar situation, the Subaru ABS
doesn't seem to pulse the brakes, rather you get more of a klunk-slide
klunk-klunk-slide sort of response, as the wheels lock and release.
I'm guessing that the ABS is mis-intrepreting the sensor inputs under
very low traction situations. At least on the Forester. having studded
tires seems to alleviate this problem, and they function about the
same as they would on pavement. I have also observed that ABS will
often mis-behave on dirt/gravel roads. I've observed a dramatic
reduction in braking response when it engages. Admittedly, I was going
considerably faster than would be considered normal and/or sane at the
time, but it was nowhere near as disconcerting on gravel as it is on
ice.

If you _haven't_ experienced the ABS effect, I would advise that you
try it out. Find a large empty parking lot. Run your car up to 35-40
MPH, and tromp on the brake pedal (do check the rear-view mirror, just
in case . . .). You should both hear and feel a deep kinda HUMMM when
the ABS kicks in. Try it again, and simultaneously work the steering,
as if you were swerving to avoid an obstacle. You should be able to
pretty much put your car where you want. Try the same thing with a
non-ABS car to see the difference, but be sure there isn't anything in
your line-of-fire, cause you're gonna slide, maybe even spin. Er, Um,
_don't_ try this with your basic SUV; very few passenger cars will
even try to flip in a slide/spin on flat unobstructed pavement, an SUV
is an entirely different thing, tho, and you might find yourself
looking at things from an entirely different perspective. Now try it
again when the parking lot has ice. You will note some differences in
the way your car responds.

Basic stuff. Lest you think this is silly, I can assure you that a
driving school will put you thru this very sort of manoeuvre. In any
event, you will feel better about your car, knowing what it feels like
to slide and recover.

FWIW, all of our kids were required to put in a season of autocross
after getting their license. Learning to control a car "on the edge"
simply makes you a better driver. For all too many out there, their
first experience of having their car get loose in a turn, or slide as
a result of too much brake pedal, is in the few seconds before they
hit something . . .

Couple years back, my usual autocross car (an MR2) was down, and I was
prepping my Legacy to go to an event just for fun . . . My wife:
"But _that's_ not a race car . . ."
"Sweetheart, they're _all_ race cars . . ." :-D
Autocross. Really, most highly recommended, and huge fun as well.
Check out the SCCA web site for details, and to find an event near
you.

Regular old "chains"; ladder-chains, I guess, not the cable-chains in
any event. And yep, they sure are a pain in the a__ to put on; almost
as bad to take off. Not to mention that usually by the time you decide
you want 'em, you're stuck in knee-deep snow, your wheel-wells are
packed with muddy slush, and you're wearing your goin'-to-work
clothes.

So now you're gonna get down on your knees and mount those chains, eh?
Easier said than done; those of you who have been there know _exactly_
what I'm talking about. Those who haven't . . . I recommend learning
how on a warm, dry afternoon in the privacy of your driveway. And send
the kids out to play lest they pick up some new and colorful language!

ByeBye! S.

Steve Jernigan KG0MB
Laboratory Manager
Microelectronics Research
University of Colorado
(719) 262-3101

"Brakes" and "braking", please.  I don't get worked up over
most spelling errors or typos, but that's the one common
spelling error that drives me nuts.  Now that I'm off that
soapbox......

Anti-lock braking systems don't engage every time the brakes
are used.  They sense when the wheels have locked up while
the brakes are engaged, and repeatedly apply and release
pressure about 10 times a second (intervals depend on the
individual system).  Slamming the brakes on dry pavement will
usually activate ABS.  ABS might engage under less brake
pedal force if the pavement is wet.  If ABS engages, the
driver will feel a rapid pulsation on the brake pedal as
well as a loud groaning noise from the ABS pump cycling.
When it doesn't engage, the braking system should feel just
like any other non ABS brake system.