Thursday, April 3, 2014
Auto Alignment Issues
Most people worry more about their engine and transmission problems than they do about their vehicles alignment. However, consideration should be given to the fact that alignment problems can compromise the vehicles traction and even the ability of the driver to steer safely and avoid accidents. There are three basic angles of alignment to address these issues. Since the objective of a wheel alignment is to ensure a proper relationship between the wheels themselves, as well as from the wheels to the vehicle and the road, it follows that the faster a vehicle is going, the more critical these adjustments become.
Toe
Toe alignment can best be explained by a view of the wheels from above. When both front wheels are exactly parallel to one another, with the distance between the front and rear of each wheel being the same, that is erred to as "zero toe" and perfect, in theory. As a vehicle is driven, the normal play in the steering and suspension linkages can change this alignment, depending on whether the vehicle is turning, braking or accelerating. It is for this reason that a slight degree "toe in" or "toe out" is often used to compensate for both rolling resistance, as well as the wear and tear of suspension components. Excessive "toe in" or "toe out" will result in uneven tire wear, due to the edges of the tire scrubbing the surface, as well as a steering pull to one side or the other under certain circumstances.
Camber
Camber ers to the position of the wheels as seen from the front of the vehicle. "zero camber" would be the position in which the front wheels were exactly perpendicular to the road. "Negative camber" is when the top of the wheels are tilted in toward each other and "positive camber" is when the top of the wheels point outward. Uneven road surfaces such as bumps and dips, as well as the movement of the suspension will cause changes in the degree of camber. Depending on the design of the vehicles suspension, the alignment specifications may allow an additional degree of positive or negative camber to compensate for this, just as when dealing with toe alignment. Both excessive tire wear and steering pull are often the results of improper camber alignment.
Caster
Caster alignment is best understood by viewing the angle of forward or rearward tilt of the steering axis from the side. "Positive caster" would be to the rear and "negative caster" would be to the front. Caster is often ignored, due to the fact that it has the least effect on tire wear. It has more to do with the stability of the steering, the effort required to steer and the returnability of the steering wheel to its center position. Positive caster is usually perred, for ease of steering return and stability. It is worth noting, however, that a difference greater than half a degree of caster from side to side can cause a vehicle to lead to the side with the least caster. Wear and tear and ride height are both factors that can affect caster and road crown can often be compensated for with slightly more positive caster on the left side.
Additional Factors
Consider that anything that creates uneven resistance or friction can cause both uneven tire wear and crooked steering. A good example of this is underinflated tires, which can bulge up on the sides, causing both of these conditions. A frozen brake caliper on one side can also cause a pull to that side. Any loose or worn steering parts, such as steering rack mounts, or suspension parts like tie rod ends can contribute to similar conditions as well. Remember that checking all of these things first to make sure that they are in proper working order will prevent further problems down the road.
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