In this work the location of the roll center (RC) is
investigated for the cases where suspension springs are not vertical. For
typical FSAE cars, the lower end of the suspension springs is attached to the
wheel upright, while the upper end is anchored to the chassis, inclined away
from the wheel. Such inclined springs will transmit a force composed of a
vertical component, which will counter gravity, and a horizontal component which
will be resisted by the suspension links. When cornering, the vertical
component, the normal reaction upward from the road, and the frictional force
combine to make a resultant that goes through the center of rotation of this
suspension system. When the horizontal component is added, the resultant no
longer goes through that center. Where the resultants from the outer and inner
wheels intersect, there will be a temporary force based roll center (FBRC).
Using the dimensions of a representative FSAE car, the RC is spaced about 100 mm
laterally away from the static central RC. Consequently, as such a car turns
from one direction to the other, the FBRC will move 200 mm from the left to the
right.