Miata Mailing List: December 1996, Message #129
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   From: (none)

Subject: Re: Effectiveness of ABS?

   Date: (none)













Gordon J Choate @ INFOEDGE.CA

02/12/96 03:35 PM



>> I can see how, on a racecourse, the ABS would not be as effective as

>> "regular" brakes.  You're approaching the same turns over and over,

learning

>> just how far you can push it and how your car will stop on the perfect

>> pavement.

>

>Even in a racecourse, ABS is proving to be an advantage!

>On the touring car championship, BMW's started to impose themselves, at the end

of the >straights, not by having a better engine, but because they could go into

a corner 'on the >brakes'...

>

>As for myself, ABS was a 'turn-off' 'till I went into 'that corner' a little

bit too fast, >on a 'little bit too wet' day !!!

>

>TTFN

>Helio&POPeye



I'll second this, through third-hand experience :-) !  In around 92 and 93, the

Williams F1 cars ran ABS until it was banned (unfair advantage).  Granted, their

ABS programming would have been track-optimized, and I have read comments that

racers don't always like road cars with ABS on a track.  A matter of tuning, I'd

think.



It's interesting that road tests in car magazines like Car and Driver and Road &

Track always seem to point out that ABS-equipped cars stop shorter than non-ABS

cars.  Case in point - R&T's recent 0-100-0 comparison test, where they

accelerate to 100 MPH, then nail the brakes.  The Dodge Viper did poorly in the

brake test - not because they're inadequate (they're quite huge), but because

they lacked ABS and had to be modulated.



I don't care how quick your reflexes are,   a human can not modulate threshhold

braking as quickly as a computer can.  As for the net effect of ABS being

half-locked and half-off, thus increasing stopping distances... I would

disagree.  When ABS detects lockup, doesn't it just release pressure until the

wheel is rotating again (not completely releasing the pressure), then reapply

pressure?  Further, doesn't ABS detect wheel rotation differentials, so it

doesn't have to wait until a wheel is completely locked up before it eases up

pressure to that wheel?  My very rusty calculus tells me (semi-intuitively) that

as the time periods between locking up and releasing pressure become smaller and

smaller (ie the ABS pulses), it becomes equivalent to braking at the threshhold

of lockup.



Anyway, I voted with my wallet - I decided to purchase a new Miata so that I

could get ABS and Torsen LSD, rather than get a used Miata without those 2 items

(in Canada, they were/are only available on the Leather package cars, and nobody

that has one seems to want to sell it!).



Gordon Choate (gchoate @ infoedge.ca)

Calgary, Alberta

96 BRG/tan