What is understeer & how to solve it

By Scott Mansell - BOSS GP driver and top UK race instructor. You can always improve your track day driving with instruction; the best way to be a safer, quicker & more confident driver.

What is understeer?

The definition of understeer is very simple: when the front tyres have less grip than the rears.

For example, you are turning around a long radius corner and the car feels like it’s ‘pushing on’. The car is not turning as much as the steering input applied, due to the front tyres are sliding over the surface of the track.

You can think of it like this: the car is not turning as much as you’d like, therefore it is ‘under’ steering, as shown in the diagram below.

The diagram below shows how understeer can affect your line around a corner - it will make you miss the apex and cause you to lose time as you aren't driving the optimum racing line.

What does understeer feel like?

Understeer is quite a subtle feeling to explain. The steering will be much lighter and if you try to increase steering angle, even just a little, it won’t make any difference to the line your car it taking. There will be a noticeable difference in steering weight between when you have frontal grip and when you don’t.

Causes of understeer

Understeer can be caused by two main problems with technique throughout a corner.

1. If you turn your car in too sharply, on entry to the corner, you may ‘shock’ the front tyres and cause them to break grip.
2. If your throttle application from the apex point of the corner is too vicious the car may understeer. This is because the weight of the car is transferred to the rear too quickly, leaving the front with little grip.

How to solve understeer

The best thing is to never get it in the first place. The problem with understeer is that to get rid of it you have to reduce your speed to less than the optimum for the corner in question. This will always cost you time.

At the first sign of a little understeer many track day beginners will increase steering further still. This does nothing! The tyres are already using 100% of their grip and increasing the steering angle will only make matters worse.

So, what to do? The whole cause of understeer is that the tyres are trying to go around a corner too tightly or too quickly. Therefore, to solve it you will have to reduce speed and/or reduce steering angle. Be sure to do this smoothly, as if you turn or lift to viciously things could get even more complicated.

As always: driving a car quickly is a balancing act.

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