By Fred Pack, PCA DE instructor
Don't get off the gas abruptly when you are in a turn. This prohibition can be difficult to follow because if you feel you are going too fast in a turn you certainly do want to slow down, but getting off the gas (“lifting”) in a turn can provoke Trailing Throttle Oversteer, often called TTO. Consider what happens when you lift in a turn: In a turn, the tires are providing the necessary grip to keep the car on the road. If you are going fast in the turn the car is relatively near the tires' maximum available grip. If you lift off the gas you are performing an act of mini-braking – you've seen how the front of the car comes down and the rear rises when you lift – just like when you brake. This puts more weight on the front tires and less weight on the rears. Tires' grip is increased when they have more weight on them, and grip is decreased when there is less weight. So, lifting in the turn has the effect of increasing grip in the front and decreasing it in the back of the car, and this may make the rear lose its grip and cause the rear of the car to slide towards the outside of the turn. At the same time, the increased grip at the front may cause the nose of the car to aim more towards the inside of the turn – this type of skid is called oversteer and when it is provoked by lifting off the gas it is called Trailing Throttle Oversteer.
So what do you do if you are going too fast in a turn? The first answer is don't go too fast in a turn! This way you won't have to deal with TTO. The second answer is that you gently reduce the gas to slightly slow the car and at the same time you can 'unwind' the steering wheel – you reduce the amount of steering you are applying. These two steps will give more grip to the tires and simultaneously require less grip from the tires for the car to be stable since you have increased the radius of the turn you are momentarily driving.
Sometimes, as bizarre as it may seem, you can get more stability in a turn by increasing the amount of gas you apply! This is because adding gas adds weight onto the rear tires and increases their grip. As you gain track experience you can try some of these techniques as useful.