What Is Caster?
Caster goes hand in hand with camber. However, instead of moving the Kingpin from side to side (as with Camber), caster is adjusted by moving the Kingpin forwards or backwards.
Moving the Kingpin backwards, towards the driver will add caster. Moving the Kingpin forwards, away from the driver will remove caster.
Caster can be used to add more grip to the front of the kart. This is done by moving more weight to the front by adjusting the height of the front suspension. This will also change the wheelbase of the kart, making it shorter or longer.
In order to get a kart to corner properly, the inside rear wheel needs to lift off the ground. Adjusting caster can help with this. Without caster, the inside wheel would never lift, causing huge amounts of understeer.
When Should You Adjust Caster?
In most cases you will be adding caster. Adding caster will give you more front-end grip. You will find that the rear of the kart will be freer, meaning you will be able to accelerate out of corners much easier. This makes it great for hairpin corners and tight angles.
You will also need to add more caster in wet conditions and when the track is slippierthan usual. This will help to reduce understeer when you turn into corners. Adding caster does make the steering stiffer though, since you will need to be moving more weight.
You might ask yourself why you would need to reduce the caster at all. If you need more straight-line speed, reducing caster will give you an advantage. This is specifically helpful with lower horsepower karts.
Less caster will give you lower rolling resistance. This also makes it a useful set up if you’re on a fast and flowing track that doesn’t have many sharp corners.
When to increase caster:
• Rear inside wheel is not lifting
• Kart is lying flat through the corner
• Rain or slippery conditions
When to decrease caster:
• Kart is physically hard to steer
• Kart is hopping during cornering
• Too much wheel lift of the inside rear tyre
What Is Toe?
Toe in and toe our refers to the angles of the front tyres. However, unlike camber, this setting refers to the ‘top down’ angle. In other words, if you were to look at the kart from a bird’s eye view, you will notice the front tyres either pointing outward, away from each other, or inward, toward each other.
This is a simple set up tool that can be adjusted, however is not used by many drivers. It has similar effects to camber. It can affect the amount of grip the front end of the kart has, and the sacrifice is straight line speed and higher levels of wear on the tyres.
That being said, too much toe in or toe out can cause excessive wear to your tyres and slow down your kart on the straights. The general rule for adjusting toe is he following:
• More toe out (wheels pointing away from each other) —creates more aggressive turn in.
• More toe in (wheels pointing toward each other) —creates more stability in your kart.
If you want the highest straight-line speed you need to run completely neutral toe, which will give you the least rolling resistance.
In most cases you will add toe out to your kart to get the highest possible grip on the turn in phase of the corner. Most drivers set and forget this and only change it when the weather conditions change significantly.
Drivers don’t tend to use toe in too much, as more speed is generally found in corners rather than the straights, but it’s not something to rule out. So try toe in (1mm each side) to see if it works for your class, tyre and circuit. You might just find that hidden advantage over your opposition!