Miata Mailing List: July 1993, Message #128
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   From: Andy Poling 
Subject: Re: RE>to ABS or not...
   Date: Wed, 14 Jul 1993 18:17:31 -0400


On Wed, 14 Jul 1993, Al Jenab wrote:
> a) It damages the brakes under repeated threshold braking situations.
> The constant pulsing of the hydraulics will destroy rotors and other stuff.

You're the first person I've ever heard this from.  Do you have a source
for this?  I'm genuinely curious, not just being argumentative.

>   Know of any Formula 1 cars with ABS?  They have traction control and
> active suspensions but no ABS that I've heard of (I might be wrong on this,
>  though).

It's only shown up recently, but at least McLaren has it available.  Prost
opted not to use it in Britain (he had some strange electronic problem in
pratice that apparently spooked him), but his teammate (who's name I can
never remember, dammit) had it.

> 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...

>
> c) They can brake faster than the ABS system under most conditions.  They don'
> t modulate the pedal faster (obviously). The ABS system
>  kicks in at impending lock-up, not at lock-up.  What defines "impending"
> is up to some statistical measure of how brain dead the average driver is
> supposed to be.

That's because ABS's goal is to avoid exceeding your traction envelope.
If it waited until you had exceeded it, you (the average you) would most
likely already be in big trouble by the time ABS came into play.

Just ask anyone who's raced a 'vette in SS roadracing why they cream
everybody else in the rain.  They'll tell you it's because they can just
stand on the brakes at the end of the straight and turn into turn one.
I'm sure there are a few at the FATTs Al - ask 'em.  :-)

I have ABS (and the LSD).  I find ABS very handy in auto-xing - I can
trail brake big time without getting into trouble.  Very seldom does it
come into play that I don't figure I would have spun if it hadn't.

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.

The only negative things I would say about the ABS are:

- it's noisy.  the first time you hear it you'll think something
has just broken (it's mounted just ahead of the passenger side
firewall, which may have something to do wiht the noises

- when you first drive away it makes a disconcerting whir/clunk
noise as it pressurizes for the first time.

Other than those two admitedly minor complaints I luv my ABS.

I can't really tell you whether my LSD ('91 silly-putty version) is much
help - it's not as obvious when it comes into play.  I know that the new
models use a Gleasen Torsen LSD - a pretty proven design.  It is probably
more effective than the one I've got.

My $0.02...

-Andy

Andy Poling                              Internet: andy@jhunix.hcf.jhu.edu
UNIX Systems Programmer                  Bitnet: ANDY@JHUNIX
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