The steering system on a racecar is a sub-system that stays largely behind the scenes in discussions around vehicle performance, yet in the pursuit of victory it plays a significant role. The design and operation of the steering system can, literally, make or break a racecar.
Like many components, the steering system is a small piece in a much bigger puzzle but, once you scratch the surface and look a little deeper, it’s clear to see the engineering is remarkably involved and its technical intricacy is up there with the best.
As the main control interface between the driver and car, the operation of the steering system has a direct influence on the chassis dynamics and the driver’s ability to accurately and confidently control the vehicle.
As its basic function, the steering system exists to provide a mechanism of changing the car’s trajectory by rotating the front wheels around a steering axis. The precise orientation of this axis in 3D space is key in defining steering kinematics, which controls the orientation of the tyre relative to the track surface as it is steered.
By defining the moment arms associated with the steering system’s operation, the orientation of the steering axis also controls the magnitude of forces transmitted to the driver from the contact patch via the system during steering, throttle and brake applications by defining the mechanical trail (caster) and scrub ratio (king pin inclination).
Optimal performance
Optimal geometry for performance usually results in large values of these parameters, which means high forces are transmitted into the structure of the system. This consideration is important on two levels.
Firstly, as the driver interfaces directly with the front wheels via the steering column, any forces generated within the system are directly felt through the steering wheel, which is key in determining not only the levels of feedback the driver receives, but also with respect to ergonomic concerns around steering effort.
Its operation must be favourable to the driver with respect to metrics such as the steering ratio, which defines the angle of steer introduced with
