Design Question: Lower A-Arm Outer Mounting


New Member
Hi All!

I'm in the process of designing the front suspension system of a Baja SAE car (think of it as a miniature UTV, ~500#, ~55" wheelbase, 12" suspension travel) and trying to figure out Roll Centers, Camber and Toe Curves...

I'm curious why all the 2WD offroad race cars I see have their Lower A-Arm Outer mounting point in line with the wheel spindle. I initially tried that, but then discovered by moving that point downward, I could raise the roll center (less body roll) and still maintain the same Camber and Toe curves by adjusting the Upper A-Arm Inner points along with Steering Rack points. It even reduces the forces in the Lower Ball Joint!

In 4WD applications, that lower ball joint has to move down to make room for the axle to key into the hub, but that's the only time I see it drastically lower than the centerline of the wheel.

Would anyone be so kind to shed some light on this for me? I'm a newbie to designing suspension from scratch, so anything helps!

Thanks a million!


P.S. First image is what I'm noodlin' up, second image is what I see in the real world!