On Thu, Feb 26, 1998 at 10:49:40AM +1100, Allen Nugent wrote:
>
> Rich,
>
> At 11:53 25/02/98 +0000, you wrote:
> >I always understood it that it was best to keep your boot down when going
>round
> >a corner so that you got the negative camber of the rear wheels, this will
>give
> >you better grip, because as the body rolls, the outside wheel will become
>more
> >upright, if you think about it, if the wheels are upright to start with, then
> >they tilt over a bit, then you are getting similiarites to positive camber.
>
> The centripetal force (between the road and the tire) is responsible for the
> camber change. One reason for accelerating is that doing so transfers weight
> from the front to the rear wheels, improving their grip. There may also be
> 2nd-order effects I haven't read about. Someday I'll have to get out my
> Classical Mechanics textbooks and suspension books, install Mathematica on
> my PC, and produce the definitive treatise.
I remember reading a book on sports car design years ago that had an
explanation of increased traction under acceleration due to precession,
complete with force diagrams. Having taken a physic course shortly
before this, I was aware that precession means that when a force is
applied to a spinning object, like a tire, the object acts like the force
was applied from 90 degrees in the direction of rotation. Acceleration
applies a forward force, but the rotation of the wheel translates that
into a downward force, forcing the tire into the pavement. Deceleration
pushes the tire up, decreasing traction (one reason not to brake in a
turn).
--
Dan Julien
'72 TR6 (on the road again, someday)
Austin, Texas
djulien@mail.utexas.edu
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