A new vehicle will leave the factory with a perfect wheel alignment. Over time, the vehicle will gradually come out of alignment. This can be due to worn parts, bad roads, or other harsh driving conditions. In addition, if your vehicle’s wheel get hit in accident or a curb check, the suspension will need to be checked for proper alignment. A proper wheel alignment will ensure that the vehicle handles safely, has good ride quality, and extend the life of your car’s tires. Below I will discuss the basics of an alignment and when and why you should have one done on your vehicle. This is especially important if the wheel get hit in accident or curb check.
Tire Wear and Angles
Front wheel alignment typically involves the following five angles: Toe-out on turns, toe, caster, steering axis inclination(SAI), and camber. These angles are comprised of steering and suspension components. A rear alignment includes the following: Setback, camber, thrust angle, and toe. If any of these angles are incorrect, it will lead to tire miss wear.
To effectively troubleshoot complaints such as pulls, vibrations, poor handling, or tire miss wear, you must be familiar with what each angle does and how they all work together. The angles that affect tire wear are camber, toe-out, and toe. SAI is related to camber so it can potentially cause tire wear. Camber and setback are not related to tire wear unless they are extremely out of tolerance from things such as an accident or major component failure. All angles can affect steering, control, and ride quality.
Caster is the tilt of the front wheels when looking from the side and it is measured in degrees. A backward tilt is considered positive caster while a forward tilt is negative. Caster will affect steering wheel return and also keep the vehicle on a straight path. A caster that is high positive will make the front wheels want to stay on a straight path. Proper caster will provide stability and smooth steering wheel return. Too much positive caster is less noticeable on a vehicle with power steering. A negative caster can cause the vehicle to be unstable and lead to wheel shimmy. A caster that is extremely negative can cause cupped tires. If the caster is out of tolerance on both wheels, the vehicle will pull to the side with the more negative or less positive caster.
Camber is the angle of the wheel when looking from the front and it is measured in degrees. An outward tilt at the top of the tire is considered positive camber while an inward tilt is negative. Perfect camber will minimize tire wear. Excessive positive camber causes abnormal outer tire wear while too much negative camber causes abnormal inner tire wear. Either one of these problems can ruin your tires quickly. It is easily noticeable when your vehicle’s tires are unevenly worn. Positive camber is similar to positive caster in that it affects steering wheel return and keeps the vehicle driving straight. Negative camber improves cornering, but it can make the vehicle more difficult to steer. Most vehicles are designed with positive camber. Rear wheels are typically designed with zero camber. The exception would be some independent rear suspensions that have a small amount of(typically negative) camber. When both front wheels are out of camber, the vehicle will pull to the side with the most positive camber. rear camber that is out of adjustment usually affects handling.
Toe is the aim of the wheels when looking from above. Wheels that are aimed inward have toe-in while an outward angle is considered toe-out. The toe angle is usually measured in fractions of a degree, inch, or millimeter. Wheels that are aligned straight with zero toe minimize tire wear. Too much toe-in or toe-out can lead to feather-edged wear on the tires. Toe-in causes inside wear while toe-out causes outside wear. On vehicles with rear-wheel drive, the front wheels are typically toed in while front-wheel drive vehicles are usually toed out to compensate for steering linkage and tire movement. Toe decreases or goes away while the vehicle is moving because the steering linkage tends to flex and the wheels straighten out. Toe usually changes when the steering tie -is improperly installed or is the incorrect length. This can lead to the wheels pointing in the wrong direction. The driver may also feel a jerk when encountering bumps or dips in the road.
Toe-Out on Turns
As a vehicle turns, the outside front wheel turns less than the inside front. This leads to a toe-out condition. Some amount of toe-out on turns is required for proper balance and to prevent the outside tire from scuffing. Toe-out on turns is set at the factory and is not adjustable. If it is out of tolerance, it is typically because of an accident. This is why it is very important to have your vehicle alignment checked after an accident.
Steering Axis Inclination
SAI is the angle of the steering axis when looking from the front. The angle is set by a line that passes through the center of the top and bottom ball joints. This angle affects stability and the feel of the steering wheel. SAI and camber work in conjunction and form what is called the included angle. A positive camber results in an included angle that is greater than SAI. Negative camber has the opposite effect.
The thrust angle represents the angle between the vehicle’s centerline and the aim of the rear wheels. A zero thrust angle is ideal because it aids in keeping the vehicle straight. A rear toe adjustment will usually fix the thrust angle. In cases where the rear suspension does not correct the thrust angle, the front wheels should be aligned to the thrust line, not the centerline. If the front wheels are set to the centerline while the rear wheels are rolling to a different thrust line, it can result in pulls, tire miss wear, and incorrect front camber and toe.
Setback results when a single wheel on an axle is set in the front or behind the other wheel in respect to the chassis. Some older vehicles were designed some setback but it is uncommon on most vehicles. In most cases, especially in the rear, setback problems are the results of a collision. In some rare cases, front caster that is extremely out of tolerance can cause setback problems.
Signs of Bad Alignment
The following are some of the top signs that your vehicle needs an alignment:
- Vehicle pulls to the left or right
- Abnormal tire wear
- Sloppy or hard steering
- Suspension or steering noises
- Steering wheel vibrates
If your vehicle is experiencing any of the above conditions, a curb check, or if the wheel get hit in accident, you should have the alignment checked immediately. Also if you have alloy wheels any scratches in most cases and be repair with our alloy wheel repair service