Automobiles: Wheel Alignment
Wheel alignment is recommended for today's cars and light trucks in at least four situations:
- When you buy new tires. If your old tires wore unevenly, they probably were replaced because of bad alignment, which you want to prevent from affecting your brand-new tires!"
- When you a rack & pinion steering unit or certain other steering parts in your car were replaced.
- When certain warning signs appear on your car, indicating that alignment is needed.
- Or about every 30,000 miles, whether warning signs appear or not.
Everyday road shock as well as wear and tear can jar a vehicle's various components, especially those around the tires and the exposed underside, which can impact its performance and its safety.
What Is an Alignment
An alignment ensures that all four wheels operate in parallel with each another, and that the tires meet the road at the correct angle. Wheel alignments adjust the distances & angles between the suspension and steering components, the wheels, and the frame of the vehicle.
Carmakers typically provide recommended specifications for each of these angles on every one of their vehicles. When the angles match the specification, the car or truck is properly aligned, and it optimizes rolling friction, tire mileage, stability of the car, and steering control.
Warning Signs Are Easy To Spot
Here are some warning signs suggesting the need for alignment:
- Look closely at all four of your tires for signs of excessive wear on one side or the tire. Also look for wear in a cupped, scalloped or diagonal stripe pattern at edges or across the tread, or uneven wear but with "feathered" edges on the treads.
- If the steering feels stiffer than it used to be, or the steering wheel does not automatically return to the center position when released.
- If the steering wheel is off-centre when the front wheels are pointing straight ahead.
- If the car wants to pull to one side, or it wanders or weaves when driving.
- If your car wants drives "crab-like" on the road, driving straight, but with the rear end cocked off to one side.
There are three basic wheel angles that determine whether a vehicle is properly aligned and drives where it is pointed. While not every angle applies to every wheel, and not all angles are adjustable on all cars, these three angles must be correctly set for correct alignment:
- Camber is the inward or outward tilt of a wheel compared to a vertical line.
- Caster is the degree that the car's steering axis is tilted forward or backward from the vertical as viewed from the side of the car.
- Toe refers to the directions in which two wheels point relative to each other. "Toe-in" means the wheels point toward each other in a "pigeon-toed" stance; toe-out means the wheels point away from each other.
A Four-wheel alignment is particularly essential on vehicles with front wheel drive and those with independent rear suspension. If the rear wheels do not follow the fronts in a parallel path, then the rear wheels are pointed in a slightly different direction, and cause "rear axle steer," affecting the vehicle's stability.
What Happens During An Alignment?
Before an alignment, the technician will begin with a thorough inspection of the entire undercar, looking for parts that are loose, bent or near failure. Then your car will be driven onto the alignment machine where the technician will check and adjust, in order, camber, caster and finally toe, beginning with the rear wheels. (Not all wheels are necessarily adjustable on all vehicles.)
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