Auto Tech USA Automotive Services
Alignment is one of the key maintenance factors in getting the most wear and performance from your tires. In addition, wheel alignment provides safe, predictable vehicle control as well as smooth and comfortable ride - free of pulling or vibration. Today's modern suspensions require a precise four-wheel alignment that can only be achieved through a modern alignment system. This applies to both front and rear wheel drive vehicles.
Aligning a car or truck involves the adjustment of the vehicle's suspension - not the tires and wheels. The direction and the angles that the tires point in after the alignment is complete, however, are critically important. There are five factors involved in setting the alignment to specification: caster, camber, toe, thrust and ride height. The following brief discussion of each aspect will help you understand the process and spot potential problems.
Caster is the angle of the steering axis (the part of the suspension that supports the wheel and tire assembly). Viewed from the side of the vehicle, an imaginary line drawn between the centers of the upper and lower ball joints forms an angle with true vertical; this is defined as caster. The illustration below shows whether this angle is referred to as positive or negative. Caster is important to steering feel and high-speed stability.
Viewed from the front of the vehicle, camber describes the inward or outward tilt of the tire.
The illustration below shows whether this tilt is referred to as positive or negative. The camber
adjustment maximizes the tire-to-road contact and takes into account the changes of force when a vehicle_ is turning.
Camber is the one adjustment that can be set according to driving habits. Generally, if you drive more aggressively when
cornering, more negative camber can be set. If you drive on highways and do very little hard cornering, more positive camber can be set.
Viewed from above the vehicle, toe describes whether the fronts of the tires are closer (toe-in) or farther (toe-out) apart than the rears of the tires. The illustration to the right shows this relationship. Toe settings vary between front and rear wheel drive vehicles. In a front wheel drive vehicle, the front wheels try to pull toward each other when the vehicle is in motion, which requires a compensating toe-out setting. A rear wheel drive vehicle works just the opposite, necessitating a toe-in setting. Stated differently, toe is set to let the tires roll in parallel (at zero toe) when the vehicle is in motion.
Ride height is simply the distance between the vehicle's frame and the road.
This is the reference point for all alignment measurements. Vehicle customizing very often
will include raising or lowering the vehicle. Don't forget to have your vehicle aligned afterward.
Also, this rule applies if you put a taller or shorter tire on your vehicle.