Why is toe-in or toe-out important to the handling of my kart?

Toe must be evenly adjusted on both sides of the kart to prevent uneven steering rate, camber angles and cornering weights. Generally toe is set to zero or up to two millimeters (5/64”) toe out. In theory zero toe will prevent “snow plowing” and give the best straight line speed, although this is only true with a zero camber angle. When camber is introduced it generates a force called camber thrust which causes the tires to scrub on the track. This force can be counteracted by toeing the wheels out slightly.

What effect does camber have on my kart?

Camber is the angle that of the tire surface to the racing surface, and as such directly influences the level of grip the front end of the kart will have. When the kart is on the ground with the driver in, zero camber gives the maximum amount of rubber contact with the road. Obviously, maximizing the amount of rubber on the track is one of the main aims of a good kart setup. The chassis flexes significantly when under load. This is why it is important to check the loaded settings of the kart as well as the settings on the stand. This is also why most karts are setup with positive camber when they are on the stand, because as the chassis flexes, you end up with neutral to slightly negative camber.

What does caster do?

Caster is one of the most important aspects of kart geometry because of the weight jacking effect it creates when the steering wheel is turned. When cornering, the inside front wheel is pushed down by the front end geometry and the outside front wheel is raised in relation to the chassis. This effectively causes the chassis to pivot around a line from the inside front and outside rear wheels. This in turn results in the inside rear wheel lifting off the track. Increasing caster should improve the initial turn in of the kart.

If I change the front track of my kart what difference will it make?

The weight jacking effects of caster can be increased or decreased by changing the front track. Widening the front will increase the jacking effect at the expense of heavy steering and a lessening of steering feel, while narrowing it will have the opposite effect. By widening the front track you are really just increasing the scrub radius.

What about rear track?

Widening the rear track will allow the weight jacking effect to unload the inside rear wheel more easily, thereby assisting turn-in. As a general rule, the front track should be run as narrow as will allow adequate weight jacking, while the rear should be run as wide as grip will allow, while still maintaining a nice balanced chassis. This will result in a flat cornering, predictable chassis, which hopefully will not bog the engine with too much grip in mid corner and slow the kart on the following straight.

Can I run different settings on either side of my kart?

Whether you do it intentionally or not, there probably will be small variations in caster from one side to the other due to the manufacturing processes used to produce the kart chassis. In theory, you could run different settings on each side of the kart to suit a particular track or racing direction. This would take a lot of testing to prove whether it works or not. Our new chassis production measuring and correction system is now being used by many of the major manufacturers, which means you only have to worry about your own adjustments, not the chassis itself.

What is chassis squareness?

We use this term to describe two aspects of the kart’s geometry. The first is the parallelism of the rear axle to an imaginary line through the front kingpins. In fact, it is not imaginary anymore, because a laser wheel alignment system will create this line for you. The second aspect is the spacing of the rear wheels in relation to the front so that the kart is symmetrical about the center line. The rear axle can be set parallel to the front once you have a symmetrical front end alignment by simply measuring with a straight edge or tape measure to the stub axles. This may involve enlarging the rear bearing mounting bolt holes slightly. The rear will then track in line with the front and prevent any “crabbing”.

Is it important to check my kart’s geometry under load?

Unless you plan to drive the kart mounted on the stand, yes! As mentioned above, the kart does flex quite significantly under load, with some chassis flexing more than others, even different models from the same manufacturer. Not only does this affect camber, but through the interacting geometries of the front end, it also causes changes in toe.

So what is the best setup for my kart?

Unfortunately, there is no one magic number or setup for all karts. Generally 1-2mm (1/32”-5/64”) toe out measured on the stand is a good starting point for dry weather. Your kart manufacturer or local dealer should be able to give good advice for you particular kart, engine, tire and weight combination.

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