- October 14, 2016
- By Admin
- In Wheel Alignment
- Tags Suspension, tread wear, wheel alignment
What is a wheel alignment, and when should you get one? It’s something that most people don’t think about until their tires show uneven wear or their car pulls to one direction, but keeping the wheels aligned can improve your vehicle’s handling and reduce tire wear long before there are any signs of problems.
A wheel alignment adjusts the suspension so that the wheels are correctly positioned on the road. There are three factors that are adjusted during an alignment:
Camber – This is the angle of the wheel from top to bottom. If the top of a wheel leans toward the center of the car, it has negative camber, and if it leans away, it has positive camber.
Toe – This is the angle of the wheel from front to back. If the wheels are toe in, the fronts of the wheels are pointed toward each other. If the wheels are toe out, the wheels are pointed away from each other.
Caster – This is the angle of the steering pivot point, where the tires are pushed or pulled by the steering rack in relation to the center of the wheel. This is tied to the position of the upper and lower ball joints that the steering knuckle and wheel move on. If the upper joint is ahead of the lower one, the steering has negative caster, and if it’s behind the lower joint, the steering has positive caster.
Negative camber positions the wheel so that most of the force is placed on the inside of the tire while driving in a straight line. When cornering, the car will lean and spread the load over the entire surface of the outside tire, increasing grip.
Positive toe will cause the tires to push against each other, creating a balancing force that improves straight line stability. Negative toe puts the inner wheel in a position for better grip when going into a corner. Positive and negative toe can also be used to compensate for suspension movement.
Positive caster improves vehicle stability at highway speeds and can increase tire lean for better grip in corners, but this also increases steering effort.
Most suspension setups are designed to use “cross-caster,” a combination of caster and camber adjustments, to cause the vehicle to naturally drift to the right. If the driver loses control of the vehicle, it will head off the road instead of into traffic. Incorrect caster and camber settings can cause the car to pull more toward one side or the other, forcing the driver to constantly correct the path of the vehicle.
How should your car’s alignment be set up? The designers of your vehicle did a lot of testing to figure out the best balance of factors for optimum performance. When you get an alignment, the tech will adjust the wheel position to get back to the factory-recommended position.
It’s usually tread wear and not handling that brings a car’s alignment to the attention of the owner. These wear patterns are caused by misaligned wheels:
Feathering – Poor toe alignment can cause the inside or outside of the tire tread to wear faster while the opposite side is worn down to a sharp edge.
Camber Wear – The inside or outside wears down a lot faster than the center of the tread, leaving a bald strip across the tire.
Heel/Toe Wear – If the toe is incorrect, the tire can scrub in a way that creates a wavy pattern that goes around the tire. Uneven wear caused by a worn suspension lets the tire bounce off the road and can cause a similar pattern to that of an out-of-balance wheel.
The current alignment is measured using an alignment machine. First, the car is rolled onto a special lift that precisely positions the car and allows reflectors to be mounted to the wheels. The machine fires lasers at these reflectors to measures the exact position of each wheel and compares it with factory recommendations.
From there, the technician makes adjustments to the suspension to get the wheels in the correct position. How these adjustments are done depends on the suspension design: some components are threaded so their length can be altered, others have adjustable bolts to change mounting positions, and some bolts have specially machined washers fitted to them to change the position of components. Once back to factory spec, the car should handle correctly and the tires should wear evenly.
If you want to get the most out of your tires, the alignment should be checked every 6,000 miles or 6 months to correct any problems before they get out of hand. It’s also a good idea to get the alignment checked if the suspension has taken a major impact, like hitting a sharp-edged pothole or curb at speed.
If your car is due for an alignment, or you’re having tire wear or steering issues, have it checked at Merton Auto Body. We’ll perform them on any vehicle, whether it’s part of routine maintenance or the suspension needs to be corrected after a collision. Visit our wheel alignment page to find out more!
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