So, while the front wheels may display negative camber as it rolls straight, when it goes into a hard turn, the wheel facing the direction of the turn will try to "straighten up," achieving maximum tread contact with the road. Since lateral loading (when the car goes into a hard turn) will try to push the top of the inside tire outward, adequate negative camber may be dialed in to compensate for this. Negative camber is regularly employed on performance vehicles (especially race cars on road courses) in order to increase the tire contact patch during hard turns. If the wheel/tire features a static negative camber angle (i.e., when the vehicle is sitting idle), more tread load is placed at the road surface on the inner shoulder/tread area. A wheel/tire that leans inboard at the top (as compared to a true vertical reference line), exhibits negative camber. If the wheel/tire is straight up (following a true vertical), this is called zero camber. A wheel/tire that leans out at the top (as compared to a true vertical) features positive camber. Always refer to the OE specifications, unless you're tuning a competition car for the demands of a particular course.Ī wheel's camber angle refers to the "lean" of the wheel from top to bottom when viewed from the front or rear of the vehicle. As a rear-drive vehicle moves forward, the front wheels tend to try to push outboard, like they are trying to crawl away from each other, while a front-wheel-drive vehicle's front wheels try to crawl inboard as the vehicle accelerates forward.īear in mind that if stiffer suspension bushings are installed (specifically control arm bushings), toe may not change as much from static to dynamic conditions, so it may very well be possible to set front toe angle closer to zero in a static state. For this reason, the initial, or static, toe setting may be slightly positive or slightly negative.Ĭommonly, a rear-drive vehicle would likely require a front wheel toe-in (positive) setting, and a front-wheel-drive vehicle would likely require a slight toe-out (negative) setting. If too much toe-out is present, the feathering will angle toward the outside of the vehicle.ĭue to compliance in control arm bushings and other dynamic variances in the suspension and steering system, we want to establish a static (vehicle sitting stationary on level surface) toe angle that will result in zero-toe when the vehicle is driven down the road in a straight line. If too much toe-in is present, the feathering will angle toward the center of the vehicle. Toe-related tread wear will cause a "feathering" wear pattern across the tread. The toe angle affects directional control, turning response and tire tread life. Independent rear suspensions usually offer rear wheel toe adjustment. Live rear axles will feature no toe angle adjustment, since this is a fixed angle. * "Zero toe" is present when the distance between the front of the wheels (ahead of axle centerline) is identical to the distance between the wheels behind the axle centerline.Īll front suspensions, regardless of design, feature toe angle adjustment at a location on the steering tie rods/tie rod ends. A toe-out condition is also called negative toe angle). * "Toe-out" is present when the wheels are further apart at the front and closer together behind the axle centerline. A toe-in condition is also called positive toe angle. * "Toe-in" is present when the two wheels on the same axle are closer together at the front and wider apart at the rear. Toe angle is achieved by comparing the distance between the center of the front of the tires to a distance between the centers of the rear of the tires on the same axle. The relationship of the right and left wheels on the same axle, as viewed from overhead, illustrates the toe angle. Here's an explanation of each of these adjustable angles from me directly to your techs, followed by an overview of all wheel angle factors involved in achieving optimum handling, braking and tire life. A number of dimensional angles are involved in wheel alignment theory, but only three of these angles are generally considered adjustable. Only by grasping the rudiments of wheel angles will they be able to appreciate how they affect the vehicle in motion. In other words, they need to understand wheel alignment theory. However, instead of blindly following the dictates of a machine, it's important for your technicians to understand wheel angles and what these angles represent in terms of drivability, braking, tire wear and handling. It also will instruct the technician to adjust angles in order to meet original equipment specifications for a specific production vehicle. Granted, a state-of-the-art computerized wheel alignment system will walk a technician through the steps and will perform all necessary calculations.
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