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Effect of ABS on stopping distances (was Re: ABS ACTIVATING @ 3MPH)
There was an article in Road & Track, I believe it was July 1997,
in which they tested the effects of ABS on stopping distances under
The car used in the test was a 600-series Mercedes, which they rigged
to allow the ABS to be turned off; they used the stock tires (Michelin
mumble, mumble Energy).
They tested on a number of surfaces using four different methods:
1) ABS on, stomp the pedal and hold it until stopped
2) ABS on, full breaking but driver modulation
3) ABS off, stomp the pedal and lock 'em up until stopped
4) ABS off, full braking but with driver modulation
(wheels locked, though?!?!)
On all surfaces, entry speed was 30 MPH, except dry pavement where the
speed was 60 MPH; distances are in feet.
I make *NO* claim that I have remembers these numbers correctly. I
am fairly certain, however, that I have approximated the difference
between ABS and no ABS...
Method -> 1 2 3 4
ice 220 220 150 170
packed snow 170 180 195 195
loose snow 180 190 150 150
fresh snow 180 190 150 150
gravel 90 70 52 52
sand 49 50 50 50
wet 35 50 90 70
dry 120 140 200+ 200+
The testers also mentioned that they didn't really believe in the
"wedge" effect on loose surfaces. While "wedges" of the surface
material did build up, they were not convinced that (smallish)
wedges of snow, etc. could have any significant retarding effect on a
As always, YMMV.