Understeer

Understeer is a term used when a car loses its ability to steer while going around a corner. The front wheels of the car lose traction and steering ability forcing the car to go wide on a bend even while trying to apply the correct steering action. To an observer it will look like the driver has not turned the steering wheel enough for taking the corner. This happens as the front wheels are carrying speed at which steering inputs are limited because the wheels are busy putting the car’s power down onto the road and trying to make it go forwards faster. Understeer is more common on front wheel drive cars as the front wheels have to do the steering and put the driving power on the road.

These are two types of factors which make a car understeer

Active factors involved (the way the car is being driven)

• Cornering speed

• Throttle

• Braking

• Steering inputs

• Weight transfer

Passive factors involved (the natural properties of the car)

• Weight distribution

• Drive layout

• Suspension & chassis setup

• Tyre type, wear and pressures

Passive factors also play a big role in determining the limit at which a car will understeer. A lot of research and development goes into developing cars so that these factors can are minimized. Understeer is likely to happen when accelerating too hard in a bend or while braking into a corner or while driving into a corner much too fast or on slippery road conditions such as rain, snow or oil.

The symptoms of understeer are:

1.      Tyre noise from the front wheels.

2.      Losing the ability to steer.

3.      Drifting towards the outside of the corner.

Correcting Understeer

Understeer can be controlled when it is taking place by reducing the acceleration of a car which will allow the driver to correct the steering input while cornering. Reducing braking when understeer happens also allows for greater steering ability around a corner. Be careful when balancing the braking and steering forces to avoid an accident and make it out of the corner in as smooth a manner as possible.

The best way to avoid understeer is to go into a corner at a controllable speed so that adequate steering inputs can be fed to the car to make it go around a corner in a smooth manner. In this case the driver does not have to apply the brakes as there is enough traction to keep the car on course and at the same time the driver does not have to change the throttle inputs because the car is moving at a pace in which it can go around the corner without losing traction between the tyres and the road.