Miata Mailing List: July 1993, Message #133
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   From: buck@granite.ma30.bull.com (Kenneth J. Buck)
Subject: Re: RE>to ABS or not..
   Date: Thu, 15 Jul 1993 09:04:50 -0400


> From: Andy Poling 
> Subject: Re: RE>to ABS or not...
>
> > b) Limits driver control.  We don't want no steenking computer modulating
> > our brake pedals.
> This may be true, but I think it's just racing ego.  How many cars have
> you seen slide straight into the runoff area because both front tires were
> locked up and sliding?  I think, once ABS becomes more commonplace (i.e.
> soon), it will be embraced as yet another technological tool/edge that you
> must employ in your effort to win...

perhaps.  Phil Hill seemed to express some positive feelings for ABS
when comparing the new Supra against the Ferrari 512TR and the Porsche
911 Turbo in the latest Road & Track (the Supra had it, the other two
didn't), and he ought to know as much as anybody when it comes to
driving on the track.

more specifically, though, i've heard it said that a drawback to current
ABS implementations is that it modulates the brakes "too late"
in the process.  unlike threshold braking, where you try to avoid
any actual lockup, ABS lets a small amount of lockup occur, such
that the wheel locks-and-unlocks multiple times (albeit quickly).
so the wheel actually spends a very small amount of time sliding,
which is detrimental to achieving minumum braking distances.

in other words, it's an approximation of the ideal braking solution,
although quite a good one, and generally fine for most needs.
while some drivers under some conditions can improve on ABS braking
distances, it seems pretty much a wash in most cases.
hopefully future ABS implementations can improve the algorithm
and approach the ideal solution even more closely.

> It has definitely saved me from t-boning a stupid pickup truck driver who
> was parked across the road around a blind turn (doing a three point turn
> VERY slowly).  I know for a fact that I can't modulate the brakes as
> quickly as the computer - especially when panic-braking.  I consider ABS
> invaluable in the rain.

i think the key here is that ABS automatically corrects for varying
road and tire conditions, on a per-wheel basis.
it's a lot harder (actually impossible) for the human to do that.
you might be driving on any combination of driving surfaces with
good or poor adhesion, and the odds are good you won't always get
the modulation right _every time_.  so maybe without ABS, you hit
2 out of 5 pickup trucks, where with ABS you hit 0.
(personally, i prefer the 0!)