Miata Mailing List: July 1993, Message #139
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   From: Dore Brian K 
Subject: Re: ABS
   Date: Thu, 15 Jul 1993 11:56:46 -0400



I don't have any experience with the Miata ABS in particular, but I recently
drove a 1993 RX-7 and was terribly impressed with the ABS behavior.  I stopped
HARD several times and was convinced that the car did not have ABS.  My
passenger insisted that it indeed did have ABS, so I found a clear stretch
of road, brought it to 100 or so and did my best to flatspot the tires.
The front tires actually locked for a split second before the ABS kicked in
and stopped the car.  I never noticed the ABS engage until after I had gone
too far and locked up a tire.  Other cars I have driven with ABS seem to
start pulsing the brakes well before locking the brakes.  We had a short
discussion about what would happen to the ABS modulation if you changed the
size or even the type of tire.  (It didn't take long to realize neither of
us had any idea)

I'm not really crazy about the idea of ABS, but the fact that it has
the potential to be able to modulate the braking power to each wheel
individually makes it real easy to see the advantages it offers in the
real world.  Consider trying to threshold brake through a crested
intersection where first the front end of the car unloads, then the
rear end unloads as the front end is comming down, then the rear end
comes down.  I my non-abs equipped car, I start to brake, the fronts loose
some of their stick as the weight gets transfered off of them, then
lock up as their adhesion to the road is lessened, then as it comes
back down and gains adheision up front, my rears lock up as they are
jounced upwards.  Without being able to modulate the fronts and rears
separately, you cannot stop as fast.  Also consider going around a corner
on a steep downhill grade where most of your weight is being applied
to the outside front tire.  It seems ABS could help a bit in a situation
like this.  Now does anyone know if the Miata ABS really does?

Brian