Wheel Alignment

Aligning a vehicle's front wheels is the job of balancing the steering angles with the physical forces being exerted. The steering angles are; caster, camber, toe-in, steering axis inclination, and toe-out on turns. The physical forces are gravity, momentum, friction, and centrifugal force. Since so many factors are involved in front wheel alignment, it is also called front end alignment, steering alignment, steering balance, or steering geometry. Alignment is more than just adjusting the angularity of the front wheels. With steadily increasing production of front wheel drive vehicles with independent rear suspension, four wheel alignment is often required. For ideal wheel alignment, certain conditions would have to be met. Both front tires will be the same brand, size, and type. Each will have the same degree of tread wear, and be inflated with the same pressure. Each wheel is properly and equally adjusted for angularity, each tire will maintain the same area of tread contact on a smooth road surface. Obviously, it is impossible to maintain all these requirements. The steering control rods are used to adjust toe-in and toe-out. The upper and/or lower control arms are adjusted to affect the camber angle. Caster is usually not adjustable. With all the weight balance factors to be checked out and corrected, it is obvious that wheel alignment is more than just an adjustment of the steering angles. The whole theory of wheel alignment revolves around balanced weight distribution on the wheels and proper tire tread contact with the road surface while the vehicle is in motion.