Kinematics 101
One of the most hotly debated, yet most misunderstood, subjects in racecar engineering is kinematics. If you want to start a brawl in a bar full of motorsport engineers, just suggest a discussion on horizontal roll centre location and then sit back and watch the sparks fly.
Yet the crazy thing is, when you strip back suspension geometry to its basics, it is not only easy but remarkably straightforward to understand. The goal of this article is to lay this all out in black and smudge.
At its core, suspension geometry does three very simple things. These are:
• Control alignment (steer angle) of the tyre.
• Control the camber of the tyre.
• Regulate and control the forces applied vertically and laterally to the sprung mass and unsprung mass.
That’s it. The first two are controlled by 3D
The thing that drives suspension geometry behaviour is force application points
Cartesian geometry. The last element pops out in a Free body diagram analysis. However, the problem we face is because suspension geometry linkages with the automobile just happened, as opposed to being designed from the ground up, this is where the misconceptions crept in. Combine this with motorsport’s resident technical hysteria / outright hostility to any analysis more complicated then 2+2 = 4 and all hell breaks
