Basics of Caster and Camber
Knowing your caster and camber are essential to any well handling machine.
Technical Director at Compkart
- 5mm Allen key
- 13mm wrench
- 3mm Allen key for any eccentric washer grub screws
In this installment of Pro Tips, Justin from COMPKART gets down to the basics on Caster and Camber. Adding or reducing either one will drastically change the way your kart handles, both in the front and the rear.
To begin either process of adding or reducing caster or camber, you'll need to first loosen your king pin bolt just enough to have a little bit of play with your stub axle.There is no need to completely remove your bolt. For most makes, you'll need a 5mm Allen key and a 13mm wrench to complete this process. There is also a grub screw that holds your eccentric washer in place, in which the COMPKART uses a 3mm Allen. Completely remove that grub screw.
Now that your stub axle is loose and your eccentric washer is free to spin, we'll go into detail of what camber and caster are, how they affect the kart, and how to change their setting.
To begin, you should know there are two types of camber: positive and negative. To achieve either, move your king pin bolt or stub axle inward or outward. Both settings achieve two different results and are equally important depending on track conditions, category, and chassis.
Positive camber is when you lean your king pin bolt or stub axle outward. This creates more tire patch on the track, leading to more grip. If you're using your sniper laser alignment tool, positive camber is above the center line, while negative camber is below.
Increasing your camber can help you in the rain, wicking away more water. Typically in the dry, however, you'll be at a neutral setting for camber most likely. Too much camber could create a loose rear end of your kart. It may also create too much heat in your front tires, feathering them and creating some long term issues.
Removing camber reduces tire contact patch, taking some of the feel away from the steering input, but creating better stability in the rear. It can also help with straight line speed as it's reducing roll resistance, something that should help lower horsepower categories.
Unlike Camber where the king pin bolt moves side to side, changing caster revolves around moving the king pin bolt forward or backward. To Increasing caster, you'll want to lean the king pin bolt backwards, and, as you guess, removing caster is leaning the king pin bolt forward.
Adding caster to your kart is what you'll want to do most of the time. This creates more weight transfer to the front and shortens the wheelbase, which essentially gives you more of a positive front-end feel by releasing the back-end of the kart.
An obvious situation to increase caster is in wet or slippery conditions. The not-so-obvious situation is when the track is grippy. You may be asking why you would increase your front-end grip in grippy conditions. The answer is because that extra grip on the track will actually overpower the back-end of the kart, providing you with that dreaded understeer.
Reducing caster obviously does the opposite -- it decreases your front-end grip. Lower horsepower categories could benefit from this as it reduces rolling resistance. You'll also want to take out caster if the steering is too heavy for the driver to turn. The kart is already creating enough turn in grip, so reducing caster should alleviate that heaviness as long as you don't go too far and create understeer for yourself.
- Camber is applied by moving the king ping bolt or stub axle inward or outward
- Positve camber is moving the king pin bolt or stub axle outward; negative is moving the king pin bolt or stub axle inward
- Positve increases tire contact patch which is good for wet conditions; negative decreases contact patch and is good for lower horsepower classes
- Caster is applied by moving the king pin bolt forward or backward
- Increasing caster is moving the king pin bolt backward; this increases weight transfer to the front and shortens the wheel base; creates more grip
- Decreasing caster is moving the king pin bolt forward, which decreases grip; this may benefit lower horsepower categories or heavy steering input by reducing rolling resistance.