Brown's Alignment Auto Repair

Alignment

An alignment is or at least should be part of standard auto repair maintenance. Aligning a car  consisting of adjusting the angles of the wheels so that they are set to the car manufacturers specifications. The purpose of these adjustments is to reduce tire wear, and to ensure that vehicle drives straight without “pulling” to one side.

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Types of Alignments

There are three types of alignments.

First is a standard front wheel alignment which is when only the front axle’s angles are measured and adjusted. Usually front end only alignment are for vehicles with fixed rear axles which is fine , but is also important to make sure the rear tires are square with the front tires. This is where the thrust alignment comes into play.

The second is a thrust alignment which takes the rear of the vehicle into consideration. Only the front is adjusted but the rear is measured to verify that it is in align with the front. A thrust alignment verifies that all 4 wheel are square with each other. Thrust angle alignments also identify vehicles that would “dog track” driving down the road. This is when the rear end is offset from the front.  The thrust angle should be zero on many solid rear axle vehicles. If it is not a trip to a frame straightening shop is required to return the rear axle to its proper location.

The third and most common alignment is a four wheel alignment. This alignment is used for vehicles with  four-wheel independent suspensions, or front-wheel drive vehicles with adjustable rear suspensions. This procedure “squares” the vehicle like a thrust angle alignment. It allows the front and rear axles to be checked and adjusted.

NOTE:  Not all vehicles are easily adjustable or fully adjustable. Some cars and light trucks take much more time to align then others. Some vehicles require aftermarket kits to allow sufficient adjustment to compensate for accident damage or the change in alignment due to other changes in the car’s suspension.

When aligning a vehicle, it’s a good idea for the vehicle to be carrying its “normal” load. This is important for people who continuously carry loads in their vehicles. Things like a trunk full of sales materials or a van full of equipment or tools can lower the vehicle’s ride height and therefore alter the alignment. Additionally, when a vehicle is used for autocross or track events, some people will sit in their car, or have Brown’s  Alignment “weight” their vehicle to include the influence of the driver’s weight on the suspension angles.

Alignment Angle Definitions

Primary Alignment Angles:

The basic angle alignment of the wheels relative to each other and to the car’s body. These angle adjustments are called the camber, caster and toe and thrust angle. On some cars, not all of these angles are made to be  adjustable.

browns alignment brake and auto repair alignment toe Toe – Primarily a wearing angle. The difference between the leading edges and the trailing edges of the tire measured at the center. Incorrect toe will result in uneven tire wear and increased rolling friction. It can cause scalloped, feathered, chopped wear patterns. Determines steering wheel position.

Like camber and caster, toe is measured by degrees and is another basic aspect of suspension tuning. When a pair of wheels are placed with their front edges pointed toward each other, the pair is defined as “toe-ins.” Toe-in will cause outside tire wear. If the front edges point away from each other, the pair is defined as “toe-outs.” Toe-out will cause inside tire wear.  Toe-in and toe-out tires will cause tire wear but can not produce a pull. If both front tires are  pointing in the same direction this can cause the vehicle to drift or pull in the direction the tires are pointing.

CambBrown's Alignment Brake and auto repair alignment Camberer – Primarily a wearing angle. The inward or outward tilt of the top of the wheel. The tire leaning in or out from top to bottom.  A measurement of zero indicates the tire / wheel assembly is exactly vertical. Incorrect camber will cause inside or outside edge wear and in extreme cases can cause a pull toward the side with the greater reading.

Camber is the angle of the wheel in relation to a vertical direction (seen from the front or rear of the car).

A negative camber measurement occurs when a wheel leans toward the chassis. The top of the tire is leaning in. Negative camber would cause inside tire wear.

A positive camber measurement points the wheel out away from the car. The top of the tire is leaning out away from the car. Positive camber will cause outside tire wear.

An ideal camber angle assures optimal tire efficiency, proper steering control, and a precautionary “anti-roll” directive that engineers have adapted into vehicle designs to negate the effects of a body roll. A faulty camber angle will create tire wear and possible a pull.

Brown's alignment brake and auto repair alignment Thrust AngleThrust Angle – The direction the rear wheels are positioned in reference to the vehicle center line.Thrust angle is the direction that the rear wheels are pointing in relation to the center line of the vehicle  If the thrust line is to the right of the centerline, the angle is said to be positive. If the thrust line is to the left of center, the angle is negative. . If the thrust angle is not zero, then the vehicle will “dog track” and the steering wheel will not be centered.  It is caused by rear wheel or axle misalignment and causes the steering to pull or lead to one side or the other. It is the primary cause of an off-center or crooked steering wheel. Correcting rear axle or toe alignment is necessary to eliminate the thrust angle. If that is not possible, using the thrust angle as a reference line for aligning front toe can restore center steering. 

Browns alignment brake and auto repair alignment Caster angleCaster Primarily a pulling angle. The forward or backward tilt of the upper ball joint, or top of the strut, relative to the lower ball joint. when this leaning toward the rear of the car, then the caster is positive, if it is leaning toward the front, it is negative. As the difference between these angles increases from side to side, so does the likelihood of a pull in the direction of the lower reading. Basically the cross caster measurement measures the difference in position of the two front tires. They should be in the same position relative to each other. If one tire is further forward or back relative to the other tire a pull will be created. Incorrect caster can result in wander and weave at high speed and lack of steering wheel “return-ability”. Extreme caster may also cause uneven tire edge wear.

Caster is used to describe the angle of a steering pivot, as seen from the side of the vehicle and measured in degrees. Caster alignment plays a large role in evaluating the “feel” of steering and the stability of high-speed transportation. Three to five degrees of positive caster is typical for most vehicles, and lower angles for heavier vehicles are used to keep steering comfortable. A faulty caster angle will cause loose or difficult steering.

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