If you've recently replaced your tires or had work done on your car's suspension, then you've probably also had an alignment performed. Most people understand that this service keeps their vehicle tracking straight, but there's actually much more that goes into a typical wheel alignment. Most shops will provide you with an alignment report after the service is performed, but to the layman this can often be baffling. Although it may look complicated at first glance, this report is more straightforward than it seems.
How to Read Your Alignment Report
The type of readout that you're given will vary depending on the particular alignment equipment used by your shop, but they are mostly fairly similar. You will usually be given a "before" and "after" report describing your alignment angles when your car arrived and after the alignment service was completed. This report describes two or three angles for each wheel on your car. These angles are referred to as "camber," "castor," and "toe." For most reports, angles that fall outside of your vehicle's specifications are shown in red boxes while angles within spec are shown in green boxes.
Depending on the type of machine used and the type of report generated, you may also see an arrow above each box. This arrow provides a visual representation of how far the angle is from specifications. The farther away from the box's center the arrow lies, the farther out of spec that particular angle happens to be.
Alignment Angles Explained
The terms may be unfamiliar, but the angles themselves are easy to understand. In most cases, improper camber is responsible for the most common symptoms associated with a vehicle being out of alignment. The camber angle of a wheel indicates how far the wheel is tilting inwards or outwards. If you are looking at the wheel from the front of the car, a wheel with positive camber will appear to lean outwards at the top while a wheel with negative camber will appear to lean inwards. This causes uneven tire wear and results in the vehicle pulling to one side.
Toe is the amount that each wheel is rotated relative to the car's direction of travel. In other words, a wheel with positive toe (or "toe-in") would appear to be rotated towards the center of the car if viewed from above. As with camber, an improper toe angle will cause tires to wear more quickly. Unlike camber, this is unlikely to cause the vehicle to pull in one direction. Instead, it may cause your car to feel as though the steering is inconsistent or unpredictable.
Finally, castor angle is the amount that the wheel is rotated forwards or backwards. This can be somewhat difficult to understand since the wheel rotates while in motion, so it's helpful to think of this as a measurement of the suspension angle. If you were to remove a wheel with positive castor, the shocks or struts would appear to be "leaning" forward. Castor is generally not adjustable during an alignment, but is affected by choice of suspension components.
What Happens When an Alignment Is Completed?
Now that you understand how to read your alignment report, you're probably wonder exactly what an "after" report should look like. While the goal of any alignment is to bring your vehicle's wheel angles back into proper spec, this is not always possible. Castor angle, for example, is rarely adjustable, and may be affected by worn or aftermarket suspension components. In some cases, worn suspension or steering components can make perfect adjustments impossible.
In general, you should expect the technician to explain any issues. If you notice that some of the boxes on your report are red, don't hesitate to ask for an explanation. In most cases, this will indicate that one or more components of your suspension or steering are in need of repair. Since proper alignment is important for vehicle stability and tire wear, these issues should never be ignored.
For more information, contact companies like Dualtone.
As the son and grandson of mechanics, I spent much of my child hood under the hood of many cars. I have listened and learned about so many different problems and how to repair them effectively. I created this blog to cover as many car problems as possible without overwhelming readers. You will find tips for troubleshooting, advice for when to take it to a professional and suggestions for when to stop driving the car or truck immediately to prevent further and more costly damage. We hope that you find all of this information helpful and useful, allowing you to have a great running car.