Date:         Mon, 10 Jul 2017 09:47:25 -0400
Reply-To:     Edward Maglott <emaglott3@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Edward Maglott <emaglott3@GMAIL.COM>
Subject:      electronic limited slip differential idea for 2wd vanagons
Content-Type: text/plain; charset="UTF-8"

I often try to solve problems in my head while driving around.  One of
those is improving traction on my 2wd Vanagon.  I've found that sometimes
even what looks like a very slight slope on wet grass is enough to stop my
forward progress with one wheel spinning uselessly while the other one has
traction but no power sent to it.  I have thought that the dune buggy style
e-brake system where you can apply the brake to either rear wheel
independently would be a good and simple solution but maybe a bit difficult
to implement in the tight area between the seats.  I've always liked the
idea of a traction control system on AWD cars that have open differentials
and just use the ABS system to slow down wheels that are getting too much
torque.

My mind drifted back to this problem yesterday while stuck in traffic and I
first thought about an electrical actuator that would put a bias on the
angle of the bar where the two cables meet and connect to the one that goes
to the brake lever.  Bell or Felder industries could design and build the
revised hardware in an afternoon. Then I thought about having separate
actuators on each brake cable that would basically shorten the length of
that cable on demand.  A knob on the dash could bias left or right.  Next
thought was speed sensors on each wheel, providing data to an arduino or
other micro-controller, that would automate that process.  One wheel
turning and the other not?  Add braking to that wheel.  One wheel turning
2X as fast as the other?  Add braking to that wheel.  So you'd pull up on
the brake lever and engage this system only when needed.  Final incarnation
of this fantasy system was to eliminate the brake handle completely and
just make it electric.  one actuator pulling each brake cable under the
van.  Rear wheel speed sensing system to bias torque which you can activate
when you are stuck.  Now, I know some cars have electric parking brakes
these days.  IIRC I was in one of those cars and when activated it
definitely sounded like mechanical things were happening, not hydraulic
things.  I do worry about the emergency brake being taken over by an
electronic system.  If I'm in a brake failure emergency, I want to be able
to mechanically operate the emergency brake, adjust how much I'm applying,
etc.  Not that the vanagon e-brake (at least on mine) would lock up the
rear wheels, but still.  On those cars with electric parking brakes, is
there any manual mechanical emergency brake?  I don't think there was on
the one that I was in.  Do you just press that parking brake button if your
hydraulic brakes fail?

So there's my idea, get out there and make one!  ;)
Edward