Last issue we discussed how you can use the accelerator pedal to help micro manage the available grip from your tyres, when driving your Evo on circuit at its limit of adhesion. We also focused on how correct use of the accelerator will aid your recovery from an understeer or oversteer scenario. Let’s now consider what part the steering wheel plays in the equation.
In order to achieve optimum speed throughout a lap, your aim on circuit is to drive your Evo in, through and out of each corner at grip limit. To achieve this you must optimise your apex speed at each and every corner on the circuit. But don’t forget, the nearer you get to your vehicles limit of adhesion, the less chance you have to correct a mistake. And by the nature of the speed you are carrying through the corners, the opportunity to make an error also ramps up. You should expect a degree of understeer or oversteer, and the ultimate Evo experience, equal lateral acceleration, a four wheel slide.
To help determine what grip is available, your steering wheel telegraphs a variety of messages to you throughout the corner. Once the braking phase of the corner is completed, your steering input will guide you through the corner on the radius you have described by design with the steering wheel.
As you turn in, your steering wheel will “weight up” as you induce a slip angle at the front tyres. Turn in too aggressively or simply enter the corner a little too fast and you may induce understeer. This is felt back to the driver via the steering wheel by “going light” as the coefficient of friction between the tyre and the road reduces.
Reduction of understeer when discussing steering input is not instinctive. An untrained driver experiencing understeer will have a tendency to keep “winding on” the steering lock to try and coax the car around the corner. What has happened as soon as you have felt the understeer (the front of the car is pushing wide and not following the trajectory you have described with your steering input) is that you have rolled the tyre on to the side wall to the point that grip is now reducing.
The correct response is often described as counter intuitive. You must reduce steering input to allow the tyre to “pop up” back onto the tread block. At this point in the corner you can reapply the steering input to negotiate the turn. If you are hugely over speed this process is repeated as many times as is necessary to safely negotiate the turn. If you are entering the corner much too quickly be careful - you may not have the room you need to recover!!!
The Evo 4 wheel drive system and AYC does an exceptional job of managing oversteer as you exit a corner at speed – but it is still possible to experience this dynamic characteristic, especially if you drive a 6 with an LSD. Oversteer is a little more challenging to correct than understeer. It requires an input on the steering wheel in the direction of the slide - in summary you steer into the slide. What you need to be aware of is that your input needs to be ahead of the yaw rate (the speed of the oversteer) if you are to recover.
Put simply if your Evo oversteers by 30 degrees, you need a 30 degree input at the steering wheel (counter steer) towards the slide to negate the oversteer. Be very aware of the speed that your hands work. If your counter steer is slow and behind the yaw rate, you will spin. Fast hands are what is needed if you are to stay on circuit. The complex nature of driving any vehicle at its limit of adhesion should always be explored in safety. These skills are practised on training days in safety on circuits with plenty of run off. Sign up for one of our MLR courses to experience and develop your technique with the experts.
Take a look at our new website www.catdrivertraining.co.uk for more information and don’t forget to register for our newsletter for even more driving hints and tips.
Safe motoring
Colin Hoad
