Correct alignment of the wheels allows a vehicle to run straight on a level highway with little steering effort and minimal tire wear. Several things can cause incorrect wheel alignment:
-Incorrect adjustment
-Bent steering linkage from hitting a pothole, curb, etc.
-Looseness in the steering linkage due to wear
There are several adjustments needed when aligning the wheels of a modern car. These include
-Toe
-Camber
-Caster
-Steering axis inclination
-Turning radius
-Thrust angle
Toe measures the distance between the front of the tires on an axle and the rear of the tires on an axle and compares the two. If they are equal, there is 0 toe. Toe is set with a slight toe-in for stability. If the toe is set incorrectly, extra tire wear will occur. Camber is the tilt of a tire towards and away from straight up. It is adjustable on most vehicles. Caster is the front or back tilt of the steering axis. A positive caster exists when the top tilts to the back of the car. A negative caster exists when the steering axis tilts forward. The caster is sometimes adjustable on the front wheels; few cars have rear caster adjustment. Positive caster helps the wheels return to straight ahead after a turn; too much makes the vehicle hard to steer.
Steering axis inclination (SAI) is the amount the steering axis leans towards the car’s center. SAI has three roles: SAI helps the vehicle return to straight ahead after a turn. SAI keeps the car going straight down the road. SAI allows the vehicle to have less positive caster for easier steering while maintaining good directional stability. Fremont Foreign Auto uses SAI to diagnose steering gear problems, as results out of tolerance may indicate worn-out steering components. When a vehicle turns, the outside wheel must travel a larger arc than the inside wheel. The alignment angle that controls this is called the turning radius, also known as the Ackerman angle.
The tires tow out during a turn because the steering arms are angled inward or outward. When you turn the wheels, they move at different amounts through their travel arc. When the rear wheels are not parallel to the vehicle centerline a thrust angle is created thrust angle is created.
A thrust angle greater than zero will make a vehicle pull to one side. When both rear wheels have zero toe, the thrust angle and the geometric centerline are the same. The direction in which the rear wheels point is called the thrust lie. A comprehensive four-wheel alignment calls for adjusting the rear wheel toe to factory specifications with the thrust angle at or near zero degrees. Fixed rear axles are not adjustable, but independent rear suspensions usually have a changeable toe. Individual rear toe adjustments will compensate for incorrect thrust angle.
Wheel alignment is both complex and essential. Increased tire wear and compromised safety result from ignoring this critical procedure. Fremont Foreign Auto is your go-to place for wheel alignment. Our state-of-the-art wheel aligner rack allows us to send out every vehicle with factory-perfect wheel alignment. We can quickly check your wheel alignment to see if it meets specifications while you are in for routine maintenance. Call us at 510-793-6067 or visit our website to get a quote and book an appointment to check your wheel alignment or any auto repair you need.