Castor, Camber, and Tow

THE EFFECTS OF CASTER?

Caster is the angle to which the steering pivot axis is tilted forward or rearward from vertical, as viewed from the side. If the pivot axis is tilted backward (that is, the top pivot is positioned farther rearward than the bottom pivot), then the caster is positive; if it's tilted forward, then the caster is negative.

Positive caster tends to straighten the wheel when the vehicle is traveling forward, and thus is used to enhance straight-line stability. The mechanism that causes this tendency is clearly illustrated by the castering front wheels of a shopping cart. The steering axis of a shopping cart wheel is set forward of where the wheel contacts the ground. As the cart is pushed forward, the steering axis pulls the wheel along, and since the wheel drags along the ground, it falls directly in line behind the steering axis. The force that causes the wheel to follow the steering axis is proportional to the distance between the steering axis and the wheel-to-ground contact patch-the greater the distance, the greater the force. This distance is referred to as "trail." 

I recommend your settings to be between 4.5 to 6.5 degrees.

 

Click HERE for the Castor Angle Calculator

 

 

 

WHAT IS CAMBER?

Camber is the angle of the wheel relative to vertical, as viewed from the front or the rear of the bike. If the wheel leans in towards the chassis, it has negative camber; if it leans away from the car, it has positive camber. The cornering force that a tire can develop is highly dependent on its angle relative to the track.

To optimize a tire's performance in a corner, it's the job of the suspension designer to assume that the tire is always operating at a slightly negative camber angle. This can be a very difficult task, since, as the chassis rolls in a corner, the suspension must deflect vertically some distance. Since the wheel is connected to the chassis by several links which must rotate to allow for the wheel deflection, the wheel can be subject to large camber changes as the suspension moves up and down. For this reason, the more the wheel must deflect from its static position, the more difficult it is to maintain an ideal camber angle.  While maintaining the ideal camber angle throughout the suspension travel assures that the tire is operating at peak efficiency.

Since most independent suspensions are designed so that the camber varies as the wheel moves up and down relative to the chassis, the camber angle that we set when we align the atv is not typically what is seen when the atv is in a corner. Nevertheless, it's really the only reference we have to make camber adjustments. For competition, it's necessary to set the camber under the static condition, test the bike, then alter the static setting in the direction that is indicated by the test results.

We recommend running 1.5 degrees on all ATV applications.

 

 

WHAT IS TOE?

When a pair of wheels is set so that their leading edges are pointed slightly towards each other, the wheel pair is said to have toe-in. If the leading edges point away from each other, the pair is said to have toe-out. The amount of toe can be expressed in degrees as the angle to which the wheels are out of parallel, or more commonly, as the difference between the track widths as measured at the leading and trailing edges of the tires or wheels. Toe settings affect three major areas of performance: tire wear, straight-line stability and corner entry handling characteristics.

For minimum tire wear and power loss, the wheels on a given axle of an atv should point directly ahead when the atv is running in a straight line. Excessive toe-in or toe-out causes the tires to scrub, since they are always turned relative to the direction of travel. Too much toe-in causes accelerated wear at the outboard edges of the tires, while too much toe-out causes wear at the inboard edges.  We like to run toe according to the atv model and suspension setup on each bike.  These factors depend on the A-Arms, Steering Stem Flag Postion, Tie Rod End Heights, Wheel Offset and Application.

Please see our "Bump Steer" Tech Guide for more info on setting your Toe.