Miata Mailing List: April 1995, Message #282
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   From: a.mccombs3@genie.geis.com
Subject: Is there ABS after market?
   Date: Wed, 5 Apr 1995 21:20:12 -0400

In response to the above question, I've seen an ad for one system in
AutoWeek, in the past (haven't seen it for a while).  I called them, got
their literature, and looked up the patent from the number in the
literature.  Basically, it's a pneumatic reservoir in the brake lines, with
very high resistance to volume change under pressure.  The theory is that
when you step on the brakes, the slight volume change premitted by this
small reservoir allows the back pressure in the hydraulic system (due to
slightly out of round drums, or slightly warped discs) to allow some "give,"
so the brakes will rotate past this high spot and the wheels will continue
to rotate.  The theory behind this is that when brakes lock, it will always
be at a point of rotation of maximum friction - a high spot somewhere.  They
insist that NASCAR is using their system.  Note, there are no wheel rotation
sensors or active pressure relief means anywhere in the system.
 
After going through all that, I'll leave it to someone else to check out
that system. If someone comes up with something aftermarket that looks like
it will work, please let us all know.  For the present, it looks like the
cheapest and easiest way to get ABS is to trade in your car for another that
has ABS.  This is fine with Miatas, but I'd like to find a system I can
install on our early Datsun 240Z - there ain't no such thing for those.
 
                                                --Jack M. & KANSEI--