Publication: Total Magazine Article 2008
Let me ask you a question. How many times on the road or circuit have you attempted to drive through a corner describing the correct line, but only turning the steering wheel once? Turning the wheel at the entry to the corner and holding the wheel on the described radius through the turn, unwinding the steering as the road straightens, avoiding any unnecessary input and remaining in the correct position on the road? Sounds difficult? Never thought about it? Or perhaps you think it`s not possible…….
Organised track days dissect the corners for you with cones, highlighting the key components of the corner. They are invaluable for safe fast laps and provide a referenced mental picture of the corner, aiding circuit knowledge and safety. Once you have learnt the circuit, you quickly realise that the cones are a guide only and may not be in the perfect place for that perfect lap. The range and differential in the type of vehicles using the circuit on a track day, make it very difficult for the organisers to place the cones in the correct place for us all – I could be in an Evo/Subaru/Nissan, you could be in a Radical.
We can dissect the corner in the respected way: Entry; Apex Clipping Point; and Exit, but CAT Driver Training has a secret weapon to simplify the process: “Single Input Steering”. Approach the corner simply looking to use all of the road and find the straightest line through the turn. Aim to enter the turn steering without correction for the duration of the corner. Aiming to use every last piece of the circuit (not the kerbs), will reduce the steering input – minimised steering gives maximum speed. If you think of unwanted steering angle as BRAKING it will add a new dimension of discipline to every corner.
Now let’s marry minimal steering input to “Single Input Steering”. Why am I so concerned with reducing unnecessary adjustment of the steering wheel through a corner? To answer that question we cannot ignore the dynamic workings of the vehicle underneath us. On circuit the springs and dampers are working overtime to keep the tyre on and perpendicular to the road. As a driver, you are responsible for weight transfer through the platform of the vehicle, in all scenarios.
When braking, cornering and accelerating, or thinking of it more dynamically, dive, roll and pitch, unnecessary adjustment transfers weight through the platform and into the tyre. If you are cornering at the threshold of grip, the unnecessary adjustment will reduce the maximum grip the tyre can offer – you will never reach true grip limit. Why? Because a tyre has an optimum weight it can support before it rolls onto the side wall and starts to slide.
There is another piece of the jigsaw to consider: Slip Angle. Turn your steering wheel for a corner and consider what the tyres are doing on the rim. They are flexing on the wheel rim as the cornering forces build up in the tyre. By design, through a turn there is an angular difference between the direction the tyre (contact Patch) is pointing and the direction the wheel is pointing.
A tyre has an optimum slip angle. Flex the tyre on the rim too far by turning into a corner too aggressively, or simply entering a corner too fast, and your slip angle becomes a slide angle – the tyre cannot support the weight of the cornering vehicle, the tyre rolls off of the contact patch. Now running on the side wall you’re losing grip. What follows will depend on how far you have flexed the tyre away from its designed profile. You could be faced with a gentle reduction in grip, to a full blown spin and a trip to the gravel trap. Remember! If your air bags are still connected, should you be unfortunate and hit something hard, don’t have you your hands across the wheel at the point of impact. You wouldn’t be the first driver to go home with a broken nose as well as a broken car.
Let’s recap minimal steering input. Take away any small unnecessary inputs and work every corner precisely. Look for the straightest line through every corner. Linking Turn In, Apex, Clipping & Exit points with one fluid linear radius will give you minimal weight transfer, the opportunity to achieve a constant slip angle and the ecstatic unparalleled excitement of finding true steady state grip limit. Remember when driving on the road or track “less is always more” – let the car do all of the hard work not the driver.
Experience tells me it is almost impossible to single input steer if you are not looking all of the way through the corner with a very long focal point. Your steering will always follow your eyes. Look at the barrier or gravel trap and that is where you will steer! If you feel nervous of a particular corner, ignore the looming hardware and keep your eyes fully focused up the road on the tarmac.
Safe Motoring until next time…. Grip limit signals and dissecting the corner.
CAT Driver Training Ltd.
Tel. 01234 757633
COPYRIGHT CAT DRIVER TRAINING LTD. NOVEMBER 2009