Friday, January 19, 2018 Detailed Auto Topics
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A wheel alignment begins with verifying and correction of the three primary angles. These include, the caster, the camber and toe angles. Engineers base these angles on the vehicle center line and level. If we properly adjust these angles, we reduce tire wear and our vehicle drives straight. Unfortunately, wheel alignment is not always properly set. Wheel alignments that are improperly done are the leading causes of tire and handling woes. A properly set wheel alignment lasts for years. We do not need to routinely realign a vehicle. When we need a wheel alignment, we will have one or more of the following symptoms.

Three symptoms of a poor wheel alignment

1. When the wheel alignment is off, the tire tread will have wear on the inside or outside. This is different from wear on both sides or in the middle of the tire tread. A tire inflation problem is more often causes wear on both sides of the tire.

2. A vehicle that pulls or veers to the right or left, may show a need for wheel alignment. The pull will not be when braking and will be consistent at different vehicle speeds. Many other things can also cause this symptom. A skilled wheel alignment technician checks all other possibilities, before changing the wheel alignment.

3. When the steering wheel is not level, when we drive straight, the wheel alignment is not properly set. Misalignment of the rear wheels may also change the steering wheel position.

Any of these symptoms, alone or in combinations, can mean a vehicle is not properly aligned. Several other things can cause similar symptoms. A trained technician can check the vehicle and advise if wheel alignment will help or not.

  A proper wheel alignment is more dependent on the skill of the person doing the job than the equipment used

Skilled and caring technicians get excellent results even when using crude equipment. An unskilled person gets poor results even with the finest equipment. An understanding of how the wheel alignment angles interact is absolutely necessary for a proper job.

We base wheel alignment on comparative measurements and level. A vehicle, which is not level, will not be properly aligned. Different size tires side to side or even improperly inflated tires grossly effect wheel alignment. A trained technician checks the vehicle for level and the air pressure before proceeding with an alignment.

a low tire will affect level and proper wheel alignment

Tires are critically important to a proper wheel alignment. Tires with different tread patterns or even differing amounts of wear can cause a properly aligned vehicle to pull. Even new and unworn tires often cause a vehicle to pull. Conicity is a defect in tires that causes them to pull right or left and is often confused with wheel alignment problems.

Conicity can be checked by temporarily switching left front and right front tires. If the pull changes direction or ceases, the tires are the problem. Setting wheel alignment with a tire that is causing a pull is a waste of money.

Toe and Tracking

Toe is the most common cause of tire wear with wheel alignment. Improper toe either front or rear will very rapidly destroy a set of tires.  When a wheel toes in or out just 1/8 inch, the tire will be dragged sideways forty-feet for every mile that is driven.

Toe in and toe out angles in wheel alignment

When two tires are closer together in the front than the rear, the wheels are referred to as toed in. Excess toe-in will increase wear to the outside of the tire. When the front of the tires are further apart than the rear, the wheels are toed out. Excess toe-out wears the inside of the tires.

Proper toe is a static reading given by the vehicle manufacturer.  By applying a set amount of toe in or toe out with the vehicle still, the proper "rolling" or dynamic toe is achieved.  Dynamic toe is a function of several factors, including suspension inclination, scrub radius and caster

The relationship of each wheel to the vehicle's center-line is also important. For instance, if the left  front wheel were toed in 1/8 inch and the right front were set straight ahead. This would produce a total toe of 1/8 inch. When the vehicle rolls forward the total toe of 1/8 inch would be split evenly between the two tires. This would result in 1/16" on each wheel and a crooked steering wheel.

A crooked steering wheel after wheel alignment indicates improperly set toe 

The two front tires always have the same toe when driving. Toe on either wheel will center itself and the steering wheel will move off center. A crooked steering wheel after wheel alignment indicates improperly set toe, either front and/or rear.

When the rear tires toe in or out unevenly, tracking will be changed. For instance if the left rear wheel toes out 1/8 inch and the right toes in the same amount. Total rear toe will be zero, but the vehicle will track off to the left. With a straight frame and unibody, rear alignment is always the cause of improper tracking.

zero total front and rear toe with improper rear tracking

Proper tracking results from both rear wheels being adjusted to precise specifications and equal distance from the vehicle center-line. Once rear toe is set, front toe is adjusted equally side to side and to a precise specification. This results in all four wheels tracking properly and a centered steering wheel.





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