How is the steering geometry defined

Steering geometry

Steering geometry

Safety, stability, performance and the handling of a vehicle depend on many factors. The chassis design and the steering system play the most important role here. Without the latter, even the best chassis is of no use. An exact setting of the steering geometry forms the basis for optimal driving dynamics.

The axle geometry is often defined as follows: "The relationship between the chassis, steering system and wheels, according to the road surface." Poorly adjusted steering geometry can lead to unwanted oversteer or understeer, especially in curves. In everyday vehicles, however, the steering geometry is only made to reduce tire wear and ensure that the vehicle drives straight and correctly.

The central components

With a few exceptions, the steering systems of all vehicles consist of the same components: steering wheel, steering system, tie rod, tie rod and steering linkage. The setting of the toe, the camber and the caster play the main role

track

The track marks the angle of the wheel to the longitudinal axis of the vehicle. A positive inclination usually creates better driving characteristics.

camber

A camber is the angle between a perpendicular to the ground and the inclination of the wheel. The concept of the camber is to keep the contact point between the wheel and the road as large as possible. The full effect is developed especially when cornering. The vehicle has more grip and the ability to make road bends at a higher speed. Most of the time you tend to adjust the camber from zero to slightly negative. This brings enormous advantages, especially in the field of motorsport. A negative camber is preferred here in most cases, as it has an extremely positive effect on handling. This can sometimes go to extremes, which, however, has a strong effect on tire wear.
However, a camber that is set too negative can have a negative effect. This can lead to a so-called lateral fall force. Both wheels press strongly against each other, which is basically not bad as long as both wheels are in contact with the road. However, as soon as one wheel loses grip, the other wheel no longer has any counteracting force. This results in the vehicle pushing against the wheel without any pulling force.

trailing

The caster describes the angle of the contact point of the extended pivot axis on the ground to the vertical of the wheel center. This mainly influences the stability at high speed and the steering effort, but also increases the wheel inclination.

At A&M

We always try to find a good compromise between tire life and grip level. Because the tire temperature is significantly influenced by the steering geometry. Furthermore, we use a wheel load scale to help, with which a chassis can be precisely adjusted to the vehicle weight (including the driver) and its distribution.
If the steering, braking and acceleration behavior are perfectly coordinated, they enable the driver to achieve optimal driving dynamics. The procedure is very individual, however, so there is no generally applicable setting. In conclusion, it can be said that the setting of the steering geometry is the fine-tuning of the car. For racing drivers in particular, this means “valuable seconds”.

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