John:
It may be helpful to define some terms. I will use
definitions from Carroll Smith in his 1978 edition of
"Tune To Win":
--Roll Axis - The straight line joining the front roll
center with the rear roll center.
--Roll center - The point through which the lateral
forces transmitted from the tire's contact patches act
upon the chassis.
--Center of Gravity - A point of equilibrium (a three
dimensional balance point).
When taken as a whole, you have two moment arms (front
and rear) created by the distance between roll axis
and roll center. If these moments are too long, the
chassis will have a tendency to roll with any
causation of weight transfer. If the CG is too high
and/or not centrally located to vehicle centerline,
handling will also suffer. I believe what Dave was
saying is that if these moment arms are too long, then
raising the roll center closer to roll axis may help
contain chassis roll and improve handling. Changing
roll center is much easier to do than changing roll
axis.
John Goodman
--- John Beckett <saltracer@servusa.com> wrote:
> OK John I've got to absorb this in small doses. Can
> you explain a few
> concepts, such as moment arm, and how CG and Roll
> Axis differ?
>
> JB
__________________________________
The New Yahoo! Shopping - with improved product search
|