A friend of mine was wondering about this, and I was hoping it could find more answers from the knowledgeable ones on this board. So here it is...

"i am trying to understand the effect that caster angles and steering axis inclination have on the camber angle of a wheel. imagine that we are looking at the left front wheel and turning it 90 degrees to the right (theoretically). the way i imagine it to work...

1. every degree of SAI (steering axis inclination) i have will translate to the same number of degrees of POSITIVE camber when the wheel is turned 90 degrees.
2. every degree of positive caster i have will translate to the same number of degrees of NEGATIVE camber when the wheel is turned 90 degrees.

correct so far?

if so...

let's assume the following about the front wheels of a vehicle:
camber = -2.5 degrees
castor = +1.5 degrees
SAI = 17 degrees

now... if i turn the wheels of the car are turned 30 degrees... i would expect the following to happen:

i would expect a +5.6 change in camber because of the steering axis (17 x 30/90)
i would expect a -0.5 change in camber because of the castor (1.5 x 30/90)

resulting in +2.6 degrees of camber when the wheel is turned 30 degrees.

but that can't be right. when i look at the wheel... it most definately does not look 2.6 degrees tilted out.

so what am i missing here?

v"

 

his formulas are f'd up

 

HAHA, i didn't write this... as i have no clue what he's asking.

hmm.. i guess the formulas could be the key to his problem.

-hS

 

missed that, corrected

I think it's the change in the steering axis inclination and not the actual steering axis inclination, but would have to go back and look to be sure