I remember reading an article in the early 80's on the Audi
Quattro Sport Group B rally car. Which did have a switch to
turn off ABS.

The switch was because braking distances in gravel or dirt
shorten if you lock up the wheels because you build a wedge
of debris in front of the wheel that slows you down much
faster. If you don't lock the wheels you don't get the wedge.

That said, I don't think that ABS shorten's braking distances
at all. You stop pretty fast when you lock up the wheels...
you just can't steer your vehicle and are dragging (and flat
spotting) four erasers down the road. If your attitude wasn't
perfectly straight when you locked you can also expect that
the vehicle will swerve when you lock.

My mid 80's Chevrolet Caprice Classic Wagon (complete with
fake wood panneling) used to lock its rear wheels all the
time. It forced me to get pretty damn good at threshold
braking, that is braking at the limit right before lockup.

Thanks,
Chris

---- Original message ----
>Date: Fri, 7 Jun 2002 22:22:44 +1200
>From: Andrew Grebneff
<andrew.grebneff@STONEBOW.OTAGO.AC.NZ>
>Subject: Re: ABS on a vanagon
>To: vanagon@GERRY.VANAGON.COM
>
>>Noticed people debating whether ABS was ever available on
US Vanagons. A
>>co-worker just bought a regular US spec '90 Westfalia which
has every option
>>imaginable, including ABS. Seen it with my own eyes! And
for those of you
>>who question the usefulness of ABS, Ben, don't cast stones
until you've
>>tried it in the snow - it's great!
>
>ABS of the day was hopeless in gravel or on dirt, though.
Just not
>designed for it, and it seriously lengthened stopping
distances, at
>least in S-Class Mercedes. If you have an ABS bus and
frequent dirt,
>try crash-stops. You might consider fitting a switch in the
ABS
>circuit so you can turn it off...
>--
>Andrew Grebneff
>165 Evans St, Dunedin 9001, New Zealand
><andrew.grebneff@stonebow.otago.ac.nz>
>Seashell, Macintosh, VW/Toyota van nut