My clubmate, Ricardo Faria, extracted an interesting chapter about car control from one of the road racing bibles: “Going Faster! Mastering the Art of Race Driving”
Mastering car control
Your biggest worry in racing is losing control of the car. It comes slightly in front of “being bog slow”. And, being slow is bad enough, but being slow and out of control is worse. To be competitive, you have to be willing, even eager, to flirt with the car’s limits. The excitement begins when you turn the steering wheel, because you know that if the car isn’t sliding you’re probably not going fast enough. But once the slide begins, there is always a measure of doubt in your mind as to whether this slide is one that will go too far or is just another of the thousands of perfectly manageable ones that have gone before. With a veteran driver, one with good car control, the doubt is small, the confidence that every slide is controllable is high.
With a novice the doubt is greater, especially if you’ve spun in the recent past, and greater still if you don’t know the reason for the previous spin. Without knowing why it happened and what you might do next time to keep the car under control, spins become random, unexplainable, events. It’s like driving around with a bomb in the car that might go off at any moment – or might not.
Genuine confidence is earned
Driving around the racetrack with this doubt hurts your performance in the car. You’re going to be slower since you don’t dare do anything that makes the car go faster, lest it fly off the track. Some would call this prudence and, while some people live quite happily with the motto “don’t take a chance” they are not often successful racers.
This is not to say that cautiousness is all bad. A worse response to the anxiety is to pump up your confidence unrealistically – to use bravado to urge yourself to go faster. It doesn’t work. If you don’t have the skill required to control a sliding car, feigned bravery will only result in more spins, more loss of control.
Confidence in your car control comes from having the experience of sliding the car and bringing it back from the edge of loss of control by making the right moves. By practicing and getting good at it, even if you’re inclined to be timid,you will be more willing to stretch the limits. If you’re overly brave, you will do better by learning that it is skill that lowers lap time and not the willingness to sacrifice your car and yourself to the barriers.
Neutral yields the best grip
Of the two cornering attitudes, the oversteering certainly looks faster than the understeering car. The best cornering speed, however, doesn’t come from either of these setups.
You’ll find that the ultimate cornering grip available from a tire comes in a narrow range of slip angle. The best slip angle will vary from tire to tire and car to car but, for now, let’s say that you get the best traction when the tires operate at a 10 degree slip angle. In Fig. 4-3, the car with the most total grip, and consequently the highest potential cornering traction, and since the slip angles are the same, the car is said to be “neutral”.
Remember, though, that the car is neutral but it still has some yaw. Many drivers mistakenly think that a neutral car simply tracks around the corner with zero yaw. It doesn’t. Neutral simply means that the front and rear slip angles are matched, hopefully in the range where the tires deliver the most traction.
Cornering balance is fluid
A Frequent mistake is to use one of these terms to sum up a car’s cornering behavior. Pronouncements like “Porches oversteer”, or “front wheel drive cars understeer”, or “mid-engines cars are neutral” are too generalized. The same car can exhibit understeer, oversteer, and neutrality under different conditions, often in the time it takes to drive through one corner. The process is a fluid one where you get a feeling for the right vehicle attitude and manipulate the controls of the car to keep cornering with just the right amount of yaw and slip.
Using the controls to alter handling balance
They key is that, although cars have designed-in tendencies toward oversteer, understeer or neutrality, you can change the car’s characteristics by using the controls in different ways.
It’s always dangerous to generalize, but the following guidelines show the handling affect of different control actions. These rules are for the most common racecar arrangement, rear wheel drive.
“Going Faster…” is one of the most recommended books to learn and settle basic road racing principles. If you want to buy it, check this link.