Do I need an Alignment?
You know your car needs an alignment every once in a while and you might even get one whenever you buy new tires. But how many people understand what is done in an alignment? What exactly is adjusted and why? I'm going to try and explain what is changed, what it is and why it's important.
Let's start by understand the three main points in a wheel alignment. They are Camber, Caster and Toe. These are the most important of the angles in the geometry of the front end.
1) Camber:
Camber is the tilting of the wheels from the vertical when viewed from the front of the vehicle. When the wheels tilt outward at the top, the camber is positive (+). When the wheel tilts inward at the top, the camber is negative (-). The amount of tilt is measured in degrees from the vertical. Camber settings influence the directional control and the tire wear.
Too much positive camber will result in premature wear on the outside of the tire and cause excessive wear on the suspension parts.
Too much negative camber will result in premature wear on the inside of the tire and cause excessive wear on the suspension parts.
Unequal side-to-side camber of 1° or more will cause the vehicle to pull or lead to the side with the most positive camber.
2) Caster:
Caster is the tilting of the uppermost point of the steering axis either forward or backward (when viewed from the side of the vehicle). A backward tilt is positive (+) and a forward tilt is negative (-). Caster influences directional control of the steering but does not affect the tire wear and is not adjustable on this vehicle. Caster is affected by the vehicle height, therefore it is important to keep the body at its designed height. Overloading the vehicle or a weak or sagging rear spring will affect caster.
When the rear of the vehicle is lower than its designated trim height, the front suspension moves to a more positive caster. If the rear of the vehicle is higher than its designated trim height, the front suspension moves to a less positive caster. With too little positive caster, steering may be touchy at high speed and wheel returnability may be diminished when coming out of a turn. If one wheel has more positive caster than the other, that wheel will pull toward the center of the vehicle. This condition will cause the vehicle to pull or lead to the side with the least amount of positive caster.
3) Toe:
Toe is a measurement of how much the front and/or rear wheels are turned in or out from a straight-ahead position. When the wheels are turned in, toe is positive (+). When the wheels are turned out, toe is negative (-). The actual amount of toe is normally only a fraction of a degree. The purpose of toe is to ensure that the wheels roll parallel. Toe also serves to offset the small deflections of the wheel support system that occur when the vehicle is rolling forward. In other words, with the vehicle standing still and the wheels set with toe-in, the wheels tend to roll parallel on the road when the vehicle is moving. Improper toe adjustment will cause premature tire wear and cause steering instability.
Sounds confusing and complicated but keeping your wheels aligned will prevent tire wear, increase fuel mileage by reducing road friction and improve the vehicles handling. Even without abuse, front wheel alignment will change under normal, everyday driving conditions. The change may be so gradual that it is not noticed at first. The first sign of something wrong usually shows up on the front tires, which develop peculiar wear patterns that will severely shorten the life of the tire. When these appear, the vehicle should have its alignment checked.
The front end components of a vehicle can be out of alignment, but not give any indication or warning signs. Shimmying and shakes in the front end are usually not caused by the car being "out of alignment," but by out of balance or lack of rotation with the tires. The vehicle pulling to one side, or unusual tire wear are the two most common "out of alignment" warning signs. Check the alignment and all wearable parts in the front end periodically. Always have the front end aligned when replacing tires. A front end alignment is commonly referred to as a "four wheel alignment" these days. Some adjustments to the rear alignment are available on most newer model vehicles, thus the term four wheel alignment.
