Now we’re getting down to the real nitty-gritty of suspension refinement. A surprising number of racers still avoid dealing with them, as with geometry in general they’re seen as another ‘black art’. Not at all alleviated by the sight of the well-to-do single seater teams producing computer controlled, highly accurate scales to make last minute corner weight adjustments or slipping wafer-thin shims in between steering arms and hubs. The truth is – its very simple to do, either through purchase of a basic gauge for a modest sum or self-manufacture for very little outlay. Your patience and time is the biggest input. As a task, setting corner weights is easier than caster, camber, and tracking setting. Bump steer is slightly trickier. For the serious competitor, or those seeking the best ‘handling’ available from the equipment fitted to their car, both are worth persevering with as they have a significant effect on the car’s over-all balance.
Balance is the key factor here. Despite all pained and careful ministrations over setting ride heights and suspension geometry, you may still have those all-important four tyre contact patches bearing unequal proportions of the total car weight. Simplest analogy of the effect this has is that of the ‘four legged table with one short leg’. On a flat floor, with four even-length legs the table is stable. Cut a bit off one leg – even as little as 0.040″(1mm) and it rocks. The shorter the leg, the greater the rocking effect. That’s exactly what happens when you have unequal loads on the contact patches, felt as the car lurching/rolling more sharply and excessively when turning in one direction than the other. The car’s stability is upset – adversely affecting its balance. A well-balanced car is generally easier to drive quicker by promoting driver confidence, an ill-balanced one seriously eroding that all-important confidence.
The task is a comparative one, so the car needs to be ‘as raced’. In our case that means with the driver or driver’s equivalent weight aboard. The aim is generally to have the front wheels bearing an equal weight, and the rear wheels bearing an equal weight, but NOT both front and rear bearing the same weight. Simply because there is generally more weight front or rear due to engine positioning, etc. Now, the important point to get your mind around for those who compete as ‘driver only’ (circuit racing, hill-climbs, sprinting, etc.) is you will have a natural weight bias to the driver’s side. Fundamentally asymmetric, you shouldn’t be aiming for a symmetrical split. There are those that do pursue this goal – Miglia Champion and Mini racing maestro Peter Baldwin being one of them – but personally I find it makes the car handle weirdly so have always followed the asymmetric principle. And then again – I’m not what you’d classify as a ‘hot-shoe’ being merely average in by driving capability.