Re: Servotronic

[David Kavanagh <dak-ignore@rochester.rr.com>]

I just thought about this again, and a parallel resistor would divide the
current going through the rack assist coil. My suggestion about the series
resistor was wrong. Anyone want to try it?

David Kavanagh wrote:
> 
> Steve, If I remember my electronics education, putting the appropriate
> value (and wattage)
> resistor in series with the rack would decrease the assist according to
> the resistor value.
> Without doing some measurements, I don't know if that requires .5 Ohms
> or 1K Ohms (or 1/4 W
> or 10 W resistor). I suppose if you knew the resistance of the rack
> (assuming just two connections
> to the rack), you could figure out what kind of power was going though
> it at 12V and pick the
> right resistor and see if it "feels" right.
> 
>         David
> 
> PS. Does the '91 200 20v have the same rack?
> 
> "Buchholz, Steven" wrote:
> >
> > While looking into some other V8 trivia I found a discussion of the
> > Servotronic system ... at least the one for the V8.  In the description it
> > showed that the system worked by varying the current through the Servotronic
> > valve on the steering rack ... with the amount of assist being increased as
> > the current through the valve increased.  Below about 12MPH the controller
> > drives the valve to saturation to get the maximum assist, but above that
> > speed it showed the speed/current function with the current going to -0- at
> > over 100MPH.  This implies that those of us who have disconnected the
> > servotronic have set the assist to the amount that it would be at a much
> > higher speed.  I don't have a problem with the assist at that level now, but
> > it should be a fairly simple matter to rig an adjustable current source that
> > would allow the amount of assist to be user selectable.  It might actually
> > be possible to "recurve" the existing module to reduce the amount of assist
> > at certain speeds, while leaving full boost when parking.
> >
> > I don't know if I want to even think about "chipping" my steering right now,
> > but it might very well be possible ... :-)
> >
> > Steve Buchholz
> > San Jose, CA (USA)