Basic wheel alignment

Strictly speaking, ride height is not an alignment angle. It can, however, affect other angles, especially caster. Many manufacturers specify ride height measurement positions for alignment adjustment. Ride height often is measured at the bottom of a front or rear rocker panel or the top of a wheel well. Because vehicle body panels are not the most accurate data points (with the possibility of collision damage), ride height is more accurately measured from points on the suspension or frame.

Many trucks are fitted with a variety of wheel and tire sizes, suspension options and lift kits. Therefore, truck manufacturers often specify different caster angles for different ride heights on the same basic truck model.

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Start With the Customer Complaint

Customers rarely complain about "an incorrect Ackerman angle," "too much caster" or even worn control arm bushings. Their complaints usually identify the effects of steering and suspension problems rather than the causes. Owner complaints that relate to wheel alignment generally relate to poor handling, hard steering, vibration or tire wear. The first step in diagnosing a problem is to determine the category into which it fits. A careful road test followed by a thorough inspection will get you off to a proper start.

A Final Word: Check the Tires

Before you begin your road test, take a close look at the tires. Most cars and light trucks should have four tires of the same size and tread pattern. At least the pair on each axle should be the same size and have approximately equal wear patterns.

Next, check the tire pressures. Occasionally; you'll find a tire that's overinflated, but probably two-thirds of the tires rolling down the highways today are underinflated. Bring all four tires to their recommended inflation pressures. Most car owners will be surprised by how a simple tire pressure check can solve problems like vehicle wander, brake pull, hard steering and a spongy ride.

During your road test evaluation and alignment measurements, remember the basic purposes of alignment angles and how they all work together to maintain vehicle motion balance.

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