Checking Wheel Alignment

Adjusting a vehicle’s wheel alignment is something that most of us look at with some trepidation. After all, it sounds like something your mechanic, in a garage with specialized equipment and years of experience, should do. In this case, you are likely right. Alignments take specialized equipment and tools as well as experience of working on vehicles. It is not something for an amateur mechanic to do.

That being said, some people may feel a mechanic is taking advantage of them because of their ignorance about alignments and how often a vehicle needs them. But don't feel that way if your mechanic does recommend this service. All cars and trucks need alignment from time to time.

There are several reasons why vehicles need alignments. You should get you wheels aligned when you buy news tires; when you have a rack and pinion steering unit or other steering parts in your vehicle replaced; or about every 30,000 miles. You should also have your vehicle aligned if you notice certain warning signs, such as the ones noted below.

What is an Alignment?

Although it may seem complicated, alignment is simply making sure the wheels are operating in parallel with one another, and that the tires meet the road at the correct angle.

Four-wheel drive alignment is standard service these days, and is important on vehicles with front-wheel drive and independent rear suspension. Two-wheel alignments may save you money up front, but your vehicle's handling and tire tread life may be compromised. When doing a four-wheel alignment, the rear wheels should follow the front wheels in a parallel path.

Vehicle manufacturers recommend certain measurement specifications for the angles created between the suspension and steering components, as well as between the wheels and the frame of the vehicle. When these angles are correct, the vehicle is properly aligned.

This means the best possible compromise has been achieved between minimum rolling friction, maximum tire mileage, stability of the vehicle on the road, and steering control for the driver.

Warning Signs of Bad Alignment

• Take a close look at all of your tires. If one or more of them has excessive wear on one side, or wear in a cupped, scalloped or diagonal strip pattern at edges or across the tread, or uneven even wear on the treads, then your vehicle may need an alignment.
• If the steering wheel feels stiffer than normal, if it does not return to the center position when released, if it is cocked to one side when the front wheels are pointing straight ahead or if the vehicle feels skittish, your wheels may need alignment.
• If your vehicle pulls to one side, tends to wander or weave, or if your vehicle wants to move with the rear end cocked off to one side while moving straight ahead, you should also have your mechanic check your alignment. However, you should be aware that wheel alignment is not always the cause of a vehicle pulling to one side.  This can also be caused by a problem with tires, brakes or power steering. A good alignment technician should be able to determine the cause.

Proper Wheel Angles

Three basic wheel angles determine whether a vehicle is properly aligned. All three of these angles need to be properly set for alignment to be correct.

Camber is the inward or outward tilt of a wheel compared to a vertical line. If the camber is out of adjustment, it will cause tire wear on one side of the tire's tread.

Caster is the degree that the vehicle’s steering axis is tilted forward or backward from the vertical as viewed from the side of the vehicle. If the caster is out of adjustment, it can cause problems in straight-line tracking. Caster has little effect on tire wear.

Toe refers to the directions in which two wheels point relative to each other. Incorrect toe will cause rapid tire wear to both tires equally. Toe is always adjustable on the front wheels and is adjustable on the rear wheels of some vehicles.

Pre-Alignment Checklist

Before alignment, the technician should take your vehicle for a test drive to determine how it is out of alignment. The test drive should be done on a flat, straight road, a road with several bumps and dips, and a road that requires left and right turns. By driving your vehicle, the technician will get first-hand experience with any problems you are describing.

The technician should also ask you when the problem started. The more he can learn from you, the better prepared he will be to tackle the alignment issues.
The technician should also check tire condition, tire sizes, steering components, brake system and driveline items for damage and wear. He should also check under the vehicle for parts that are loose, bent or near failure, as well as check the front end and steering linkage.

Measuring the ride height is also something that should be done before adjusting alignment. A technician should measure a vehicle at various points to see if it matches the heights recommended by the manufacturer. If it doesn't, spring replacement is likely needed before wheel alignment. If your vehicle's ride height is incorrect, there is no guarantee that alignment will fix the handling, ride and tire wear problems.

Aligning Your Vehicle

After everything else has been checked, your vehicle should be driven onto an alignment machine. The technician will check and adjust, in order, camber, caster and toe, starting with the rear wheels. He may use wrenches and special tools to make necessary adjustments to align your vehicle.

Once your technician is done with the alignment, your vehicle should be taken for a test drive to determine if the handling was compromised or improved by the alignment, as well as to see if the steering wheel is centered.

Your technician should use all the tools and equipment at his disposal to make sure your vehicle is properly aligned. If you feel as though you are still having problems with alignment, don't hesitate to take your vehicle back to the shop. After spending your time and money on alignment, you want to make sure there are no problems.