TECHNOLOGY – CONSULTANT
Springs, roll and cornering balance
Altering the set up using pre-load or stiffer springs Q S
As I understand it, the stiffer the coil spring, the more weight is put on that corner, therefore planting the tyre more. My question is, what is the difference
between the stiffer coil vs body roll? For example, a stiffer right front coil should put more weight on that tyre, giving it more bite – therefore making the car steer better. However, you used to hear all the time about NASCAR teams taking spring rubbers out of the right front when they are tight to allow the chassis to roll over on the right front, making it turn. Is it because this allows the left rear to lift, which makes it turn? Please explain, in simple terms.
tiffening the right front spring, or adding pre-load to it, does load that tyre more, and does make it
produce more cornering force, in a left turn. However, this comes at the
expense of left front tyre loading. The spring change can’t change the total load on the front wheel pair, only the distribution of that total between the right front and left front. The spring change also
loaded more equally, than with a softer right front spring. Now here’s the key: when
you concentrate the load on the outside tyre, you lose more cornering power on the inside tyre than you gain on the outside one. This is because grip from a tyre increases with load, but at a decreasing rate. Therefore, when you load the
fronts more unequally and the rears more equally, that hurts
“the spring change can’t change the total load on the front wheel pair, only the distribution”
can’t change the total load on the rear wheel pair, the right wheel pair or the left wheel pair, only the diagonally opposite wheel pairs. So rear wheel loads when
cornering are also affected by the front springs. The total rear wheel load doesn’t change, but its right / left distribution changes, oppositely to the front wheels. This means that with a stiffer
When you load the front tyres more unequally and the rears more equally, that improves the available cornering force at the rear
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www.racecar-engineering.com • February 2012
right front spring, the front tyres are loaded more unequally when cornering, and the rears are
available cornering force at the front and improves available cornering force at the rear i.e a tighter car. That’s the condition with the spring rubber in the right front. Take the rubber out, and you load the fronts more equally, and the rears more unequally. That helps the car stick at the front, at the expense of the rear, ie a looser car. It works this way on dirt too,
contrary to what some people will tell you.
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