Re: Why did tires 'chirp' in panic stop?

["Christopher A. Woodward" <cwoodwar@bellsouth.net>]

I think we're overlooking some simple laws of physics here.  Any time your
vehicle is under acceleration (either negative or positive), the tires are going
to "skid."  If the acceleration is great enough, your tires may make the
"chirping" sound you referred to, which is caused by a great enough difference
between tire rotation speed and pavement speed (hopefully 0, unless you're
driving on a moving sidewalk... ;-) ).  All the ABS system does is monitor wheel
speed, and if it detects lock-up, it modulates braking pressure.  Up to 6 times
a second, I think.  Regardless of this, the tire is still "skidding."  It's just
going from skid to roll 6 times a second.  If the system is working optimally,
it probably will chirp as you approach "threshold braking."  No, I'm not
claiming to be an engineer, just go to an engineering school and hear the
TECHies talking around campus....  ;-)

Every single ABS-equipped car I've driven, from 87 to 98 WMB's to Niss@ns, to
'folks wagens, etc. to our beloved Audis have behaved this way.

Chris
'97 A4t
'90 CQ