Do they Work?

Do Rig Tests Work?

Yes, but with caveats.

Certainly, four post rig tests provide an insight into the way the suspension interacts with other elements of a vehicle, and can reveal characteristics that are difficult to identify otherwise. Equally, vehicle deficiencies that have been hidden by a particular suspension set-up (and cannot be detected by a rig test) may well be exposed if the set-up is changed radically. Occasional spectacular successes and spectacular failures can be attributed to these features of a four post rig test.

More usually, however, a test rig is simply one of the tools that are used to achieve and maintain optimal suspension performance for a vehicle and, for example, the rigs at Cranfield and Thetford have been used on a regular basis by the last five winners of the BTCC championship.

It is important to realise that rig tests in isolation are unlikely to yield an optimal suspension set-up.

The suspension of a vehicle performs several functions, some of them conflicting (more). For example, a linear style of damping is most effective at dissipating energy from a vehicle, but a linear style of damping controlling the steered wheels provides little feedback to the driver and implies a large steering time constant. It follows that moving the style of damping towards linear might improve the vehicle, but is likely to make it more difficult to drive; at best, a driver will have to adapt his driving technique (which requires track time); at worst the driver/vehicle combination will be slower.

The requirement to control the attitude and ride height of an "aerodynamic" vehicle at high speeds further complicates matters (more), and the task of blending low and high speed performance of a suspension is an exacting one.