How does Caster play with Camber

[Norm Peterson]

The caster camber relationship is somewhat tricky to envision. The common caster measurement method of turning the front wheels 20 degrees, zeroing the gauge, turning the opposite 20 then reading caster has always freaked me out.

You can think of the 20° as being little more than a fortunate coincidence. There's a little math involved, and 20° ends up being pretty close to making caster equal to 1.5 times the difference in camber (which is what zeroing the gauge turned 20° the first way and turning to 20° the other makes easy when the 1.5 factor is built into the scale on the caster vial) . . . plus 20° is an angle that nearly any car can get the wheels steered around to.



CTX - picture a right side wheel with its alignment set to 0° camber and some amount of positive caster (say +10°). Now suppose you could steer that wheel 90° into a left turn - think crosswise in the car ahead of the ball joints. Now the wheel would then be sitting at -10° camber looking from the side of the car, which would now put you looking in the plane of the wheel (just like from the front with the wheel not steered at all). At any angle less than 90° steered, you'll pick up less than than that 10°, as some function of just how many degrees you steered it (there is a slight complication that doesn't matter at 90° steered that's best left for later discussion).


Norm