Wheel Alignment

Proper alignment to Nissan or Infiniti specs is one of the key maintenance procedures in helping to minimize tire wear, and maximize the handling, steering and suspension functionality of your customer’s vehicle. Conditions like vehicle pull or drift to the right or left when driving straight is a symptom of a with wheels out of alignment. Other conditions such as premature or uneven tire wear and steering wheel off center are also symptoms of a vehicle out of wheel alignment. A vehicle is said to pull if, with no steering input and the vehicle travelling at 60 mph in a straight and level lane, all four wheels leave the lane within seven seconds. Wheel alignment consists of adjusting the angles of the wheels so that they are parallel to each other and perpendicular to the ground to set to the vehicle specifications.

Caster, Camber, Toe and Thrust Angle

The primary suspension angles that need to be measured and adjusted are caster, camber, toe, and thrust angle.

Caster

Caster is the angle to which the steering pivot axis is tilted forward or rearward from vertical as viewed from the side of the vehicle with respect to the area where the tire contacts the road. If a vehicle has symptoms of improper caster it will probably pull toward the side with less positive caster. Caster has little or no effect on tire wear. Positive caster means the steering axis tilts rearward. Negative caster means the steering axis tilts forward. If the caster is too negative the steering will be light and the vehicle will wander away from a straight line. Nissan and Infiniti vehicles normally are adjusted to positive caster. Positive caster provides directional stability and helps the steering wheel return after cornering.

Camber

Camber is the inward or outward tilt of the top of the tire from the vertical axis of the wheels when viewed from the front. If a wheel is tilted outward from the center of the vehicle it has positive camber, if it’s tilted inward from the center of the vehicle it has negative camber. Camber set at the optimal setting ensures a minimum of tire wear because it achieves the largest possible tire contact area. This is because the camber stays near zero degrees while the vehicle is moving. While negative camber improves grip when cornering, improper camber adjustment will cause the vehicle to pull to the side with the most positive or negative camber adjustment, and in extreme cases produce tire edge wear.

Toe

Toe is the inward or outward position of the front of a tire as viewed from above the vehicle. Toe is measured as the distance between the front and rear of a pair of tires. Improper toe may be observed as the tires pointing to the left or right towards or away from the centerline. The toe angle identifies the direction of the tires compared to the centerline of the vehicle. Improper toe conditions cause wandering or drifting, excessive tire wear and steering wheel off center symptoms while driving straight. When you steer a vehicle through a turn, the outside front wheel has to navigate a wider arc than the inside wheel so the inside wheel steers at a sharper angle than the outside wheel. When a vehicle’s toe is incorrect its tires may pull and wear unevenly. Toe is the most critical alignment setting relative to tire wear.

Thrust Angle

Thrust angle is the direction that the rear wheels are pointing in relation to the center line of the vehicle. If the thrust angle is not zero, the centerlines of the rear wheels will not be parallel to the centerline of the vehicle. Thrust alignment is measured by calculating the difference between the centerline of the front and rear wheels. Improper thrust angle may cause the vehicle to drift or the steering wheel to be off center. During a four-wheel alignment if the rear toe is adjustable, adjust it and then the front toe. If the rear toe is not adjustable, set the front toe to compensate for the thrust angle allowing the steering to be centered.

Four-Wheel Alignment

Four-wheel alignment is the appropriate alignment on all vehicles with four-wheel independent suspensions or front-wheel drive vehicles with adjustable rear suspensions. A four-wheel alignment involves adjusting the rear wheels to achieve proper camber, toe and thrust angle, then adjusting the front wheels to the same vehicle centerline. Four-Wheel Thrust Alignment is the recommended alignment procedure to be performed on all Nissan and Infiniti vehicles (with the exception of GT-R). The four-wheel thrust process helps ensure that the vehicle is properly aligned so it will go down the road straight, and helps ensure proper “centering” of the steering wheel. Of course it’s always recommended that you use the right alignment machine. You must use a properly calibrated alignment machine that will give accurate results when performing alignment checks. The alignment rack itself should be capable of accepting any Nissan or Infiniti vehicle. Refer to the Infiniti TECH-MATE Service Equipment Catalog for alignment equipment recommendations.

Preliminary Vehicle Checks and Inspection

Always road test the vehicle before performing alignment procedures. Verify the customer’s concerns, to conditions like pull, drift, or steering wheel off-center. Apply the Steering Wheel Offset Gauge stickers, and a Road Crown Gauge to the vehicle before performing a road test or any wheel alignment procedures. When the road test is completed, remove the Road Crown Gauge, and leave the Steering Wheel Off-Set Gauge in place.