In this section we will be explaining the information that pertains to the front end of the chassis encompassing the front spindle adjustments of caster/camber, wheel alignment, and width.
Caster is the inclination of the front kingpin by which the front wheels turn. On all vehicles there is caster inclination. On your Top Kart there is what can be called a significant amount of inclination.
This means that when you turn the steering wheel, not only are the front tires pointing left and right, they are also moving up and down. This allows the relative weights of the rear tires to be manipulated and make the turning of the chassis more efficient. Since the rear axle solidly connects both rear tires and mandates they spin at identical speeds, getting any brand of racing kart to turn is inherently very difficult.
If you don’t believe this, try putting your friend in your kart, and manually push your kart around on the ground. Going straight is significantly easier than when your friend is turning the steering wheel. Without caster, turning a kart would be next to impossible. You can use caster to influence how your Top Kart turns in to and through corners, simply by spinning the caster pills which come standard on your chassis. Typically in most situations, increasing the inclination of the front kingpins (adding caster) will provide more rear tire adhesion to the track. This is because due to the front inclination, more mechanical energy is being transferred from the front of your chassis toward the rear. This creates more twist, or torsion in the chassis tubing.
Conversely, decreasing the inclination of the front kingpins by spinning the caster pills in the opposite direction will reduce rear grip, or make the rear tires adhere less to the track surface. Most often, Top Karts prefer to start their racing weekends with more caster and end with reduced caster. Remember to take in to account the natural grip level of the track itself, tire wear, tire compound, as well as other influencing factors which impact the optimization of your Top Kart caster settings.
Camber angle is the angle made by the wheels of a gokart; specifically, it is the angle between the vertical axis of the wheels used for steering and the vertical axis of the chassis when viewed from the front or rear. It is used in the design of steering. If the top of the wheel is farther out than the bottom (that is, away from the axle), it is called positive camber; if the bottom of the wheel is farther out than the top, it is called negative camber.
You can think of Camber as more of a timing mechanism adjusting at what point of the corner you are wanting the most traction of the tires on the track surface. As an example, having an increased negative camber will give more grip on turn-in immediately and the opposing effect is increased positive camber allowing you to give the kart more grip on exit of the corner.
Wheel alignment also commonly referred to as TOE is typically set by millimeters (mm) in sprint karting. Toe is the degree to which the front wheels point toward or away from each other. Front wheels pointing toward each other is toe-in and toe-out is the opposite of toe-in. Toe-in makes a kart more directionally stable, but can contribute to poor turn-in to corners. Toe-out can cause the kart to be directionally unstable, but can assist the kart turn-in to corners well. With toe-out, the inside front wheel moves down in relation to the chassis more than it will with zero toe or toe-in.
Front width allows the increase or decrease in front grip of your go kart. It is a quick and easy basic way to adjust whether your kart needs to have more grip or less grip. If you happen to be fighting an oversteering issue then typically you would want to bring the wheels inward to create less front end grip slowing the steering down.
This is the standard Top Kart setup for wheel spacing. Start your weekend off with 20mm of spacing on the inside of the wheel hub (1 Big 10mm, 2 Small spacers 5mm).
If your chassis is Understeering going into the corner, to get to the apex you can start by widening your front end a small (5mm) wheel spacer. Increasing your front track width will allow more of the tire to be used upon steering input having you turn the wheel less on initial turn-in.
If your chassis is Oversteering going into the corner, you can start by narrowing your front end a small (5mm) wheel spacer. By decreasing your front track width you will use less of the tire upon steering input and slow the front end down upon initial turn-in.