[A4] Intro and ABS brakes question

Kent McLean kentmclean at mindspring.com
Mon Jan 31 11:04:39 EST 2005

Greg Myers wrote:
> How sensitive are the ABS brakes supposed to be? This car will not stop
> on snowy roads! The ABS activates with only the slightest pedal pressure
> and the car just keeps on going with very little braking action.

If your ABS kicks in at the slightest opportunity, you may have
a problem with it.  But... ABS is not magic.  It won't stop your
car on ice as quickly as it stops it on pavement. The friction
isn't there for that to happen.

All ABS does is this: it senses a locked wheel and eases off
the brake (releases pressure) until the wheel spins again. It
does this many times per second; that's the pulsing you feel.
On really icy roads, the ABS may spend more time releasing the
brake than it does applying the brake, giving you the sensation
that the brakes don't work.

One option is to not brake so hard that you activate the ABS.
Apply just enough brake to slow down, but not so much to
activate the ABS (threshold braking; right on the edge of
lockup).  You still won't stop as fast as on dry pavement, but
you'll be in control. That is, if your wheels aren't locked,
you can turn (which is why ABS is good).  But if you go too
fast into an icy corner, neither threshold braking nor ABS
will save you.


Kent McLean
'94 100 S Avant
'89 200 TQ, "Bad Puppy" is no more

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