Handling
The way the suspension is set up will determine how a car handles and can be used to fine-tune road manners.
There are three main types of handling characteristics.
Oversteer is when the rear of the car loses grip and tries to take a wider line than the front - aka sideways, it is the basis for drifting. This happens when the front wheels have more grip than the rears, particularly on powerful rear-wheel drive cars. Typically, the remedy is to lift off the power slightly to regain grip gradually and steer into the direction that the back is sliding known as opposite lock. However, lift off completely and you can get a situation where the rear tyres suddenly regain grip and the weight transfer throws the back of the car the other way, inducing a pendulum effect, or fishtailing. Frantic steering wheel twirling normally results and if you're lucky, you get it into a straight line eventually.
Understeer, on the other hand, is what most road cars exhibit when they approach the limits of the front tyres' grip, since it tends to be the safest option. Understeer is when the front of the car runs wider than expected, and the instinctive reaction is again to lift off the throttle slightly. On most road cars, the weight transfer to the front of the car will load the front tyres, provide more grip, the car will tighten into the turn and you'll go where you want to go. However, and it's a big however, lift off completely and you can induce liftoff oversteer, where the sudden weight transfer towards the front of the car unloads the rear tyres and they start to slide. Contrary to oversteer in rear-wheel-drive cars, the remedy now is to nail the throttle and use the front-wheel drive and weight transfer to pull the car straight.
Neutral handling is widely accepted as the most satisfying setup for a driver. This is where the front and rear tyres will begin to lose grip at the same time. So at the limit, a relatively graceful four-wheel drift will result. And as the driver backs off the throttle, all four wheels will regain grip evenly, without any heartstopping moments.
The suspension setup and specification can be used to tune the characteristics the driver wants. For example, some drivers like frontwheel-drive cars to oversteer instantly, giving a feeling of rearwheel-drive, as that's what they prefer. others may want to induce understeer, so that they can generate lift-off oversteer before getting back on the power to pull the car straight. It's all about personal preference, at the end of the day.
As a rough rule of thumb, inherent handling characteristics can be altered in the following ways:
To increase understeer in a front-wheel-drive car:
- Stiffen front springs
- Stiffen front dampers
- Stiffen front anti-roll bar
- Increase front tyre pressures
- Increase front toe-in
To decrease understeer in a front-wheel-drive car:
- Soften front springs/dampers
- Stiffen rear springs/dampers
- Stiffen front anti-roll bar
- Decrease front or increase rear tyre pressures
- Add rear toe-in
To increase oversteer in a rear-wheel-drive car:
- Increase rear tyre pressures
- Increase rear toe-in
- Increase rear spring stiffness
- Increase rear damping
To decrease oversteer in a rear-wheel-drive car:
- Effectively, increase understeer
