A car's alignment measures the suspension angles and components adjusted to ensure complaint and optimal steering and handling. The most common problem caused by improper wheel alignment is excessive and premature tire wear. Some common symptoms include a crooked steering wheel, a "pull" towards one side while driving straight and most importantly uneven tire wear.
What does an Alignment Adjust?
Caster: The angle that we call "Caster" is used to tell the forward or backward slope of a line drawn through the upper and lower steering pivot points, when viewed directly from the side of the vehicle. Caster is expressed in degrees and is measured by comparing a line running through the steering system's upper and lower pivot points of your steering system, to a line drawn perpendicular (straight up and down) to the ground. Caster called "positive" if the line through the steering points slopes towards the rear of the vehicle at the top, and "negative" if the line slopes towards the front of the vehicle.
Why isn't caster the same on all vehicles? Caster angle settings allow the vehicle manufacturer to come up with the correct balance of steering effort, high speed stability and front end cornering effectiveness that they want to achieve. Increasing the amount of positive caster increases steering effort and makes for better straight line tracking, and improves the vehicles high speed stability and provides more effective cornering. Positive caster also makes the tire lean more, when cornering, as the steering angle increases.
Camber: The angle that is called "Camber" tells how far the tires slant away from vertical when viewed directly from the front or back of the vehicle. Camber is measured in degrees of tilt from the vertical. Camber is called "negative" when the top of the tire tilts in towards the center of the vehicle and "positive" when the top of the tire leans away from the center of the vehicle.
Toe: The suspension angle called "Toe" measures the exact direction the tires are pointed compared to the centerline of the vehicle when viewed from directly above. Toe is expressed in either degrees or fractions-of-an-inch, and an axle has "positive toe" or "toe-in" when if you run an imaginary line through the centerlines of the tires, the lines intersect in front of the vehicle, and have "negative toe" or "toe-out" when they spread apart. Toe settings are generally used to help compensate for the suspension "give" built in for ride comfort, in order to help tires wear longer. Toe can also be used to adjust the vehicle's handling.
The vehicle's toe is one of the most important settings in an alignment as it relates to tire wear. A toe setting that is just a little off its correct setting can mean a big difference in how your tires wear. If the toe setting is just misadjusted by 1/16-inch off, each tire on that axle will scrub almost seven feet sideways every mile! As an example, that translates to the front tires "scrubbing" in a sideways motion over 1/4-mile during every 100 miles you drive! Incorrect toe robs you of tire life, and negatively impacts handling.
Thrust Angle: The thrust angle is an imaginary line drawn perpendicular to the rear axle's centerline. It compares whether the rear axle is lined up with the centerline of the vehicle. It also tells if the rear axle is parallel to the front axle and also that the wheelbase on both sides of the vehicle is the same.
If the thrust angle is not correct on a vehicle with a solid rear axle, sometimes more than an alignment is needed, it might need a trip to the body shop to straighten the frame and position the rear axle correctly.
If a vehicle has independent rear axles, (also called independent rear suspension) it can have incorrect toe-in or toe-out on both sides of the axle, or may have toe-in on one side and toe-out on the other. This can be adjusted in an alignment.
If you are concerned about the way your vehicle is performing and think you may need an alignment, please do not hesitate to contact us at Bustard Chrysler in Listowel!
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