The front wheels of the car are installed with their tops tilted outward or inward. This is called “camber” and is measured in degrees of tilt from the vertical. When the top of a wheel is tilted outward, it is called “positive camber”. Conversely, inward inclination is called “negative camber”. In early automobiles, the wheels were given positive camber in order to improve the durability of the front axle, and to cause the tires to contact the road surface at right angles to prevent uneven tire wear on roads where the center of the road is higher than the edge. In modern automobiles, the suspension and axles are stronger than in the past and road surfaces are flat, so there is less need for positive camber. As a result, tires are being adjusted more toward zero camber (and there are some vehicles with zero camber). In fact, negative camber is now commonly employed in passenger cars to improve cornering performance.
SERVICE HINT:
If the wheels are given excessive positive or negative camber, this causes uneven tire wear. If the wheels are given excessive negative camber, the tires wear quicker on the inside; if the wheels are given excessive positive camber, the tires wear quicker on the outside.
Negative Camber
When a vertical load is applied to a cambered tire, force is generated in the horizontal direction. This force is called “camber thrust” and operates to the inside of the vehicle for negative camber and the outside of the vehicle for positive camber. During cornering, because the vehicle leans to the outside, the tire camber becomes more positive, the camber thrust to the inside of the vehicle is reduced, and cornering force is reduced. The negative camber suppresses the positive camber of the tires during cornering and helps maintain proper cornering force.
Camber During Cornering
When a vehicle turns a corner, the camber thrust on the outside tires acts to reduce the cornering force due to the increase in positive camber. Centrifugal force tilts the turning vehicle due to the action of the suspension springs, changing the camber.
HINT:
Cornering is always accompanied by centrifugal force, which tires to force the vehicle to turn in a larger arc than intended by the driver unless the vehicle can generate a sufficient counterforce – that is, centripetal force – to balance this. This centripetal force is generated by the deformation and side-slipping of the tread that occurs due to friction between the tire and the road surface. This called cornering force.
Camber During Cornering
When a vehicle turns a corner, the camber thrust on the outside tires acts to reduce the cornering force due to the increase in positive camber. Centrifugal force tilts the turning vehicle due to the action of the suspension springs, changing the camber.
HINT:
Cornering is always accompanied by centrifugal force, which tires to force the vehicle to turn in a larger arc than intended by the driver unless the vehicle can generate a sufficient counterforce – that is, centripetal force – to balance this. This centripetal force is generated by the deformation and side-slipping of the tread that occurs due to friction between the tire and the road surface. This called cornering force.