Today we're discussing go-kart rear axles. When it comes to motor racing, cars have suspension. So karting is different because the rear axle acts like a suspension. It might flex a little bit here and there depending on the stiffness of the axle, but realistically it doesn't spring like suspension does.
So, it's important to use it as a tuning tool depending on the conditions that you are driving in. You might find if it's 15 degrees or it's 35 degrees, you might have to use a different axle, or depending on the tire compound or the changing grip levels across a race weekend.
Drivers & mechanics can also change the length of the axle. The different stiffnesses change how much the kart flexes in the rear. There are different size axles for cadet karts compared to a senior kart. It's important to know that most kart manufacturers send karts out with a neutral medium axle. Now, the reason why karts are designed around that neutral setup, is it gives you a bigger window to fine tune your setup of the kart. You're very limited with the changes you can make when you're at one end of the spectrum. That’s why kart manufacturers design karts around a neutral setup, and at least that way you can fine tune the chassis it if it's not quite right. You’re able to try a softer axle or to a different length axle.
When it comes to shortening your axle, that changes how much the axle springs out of corners. A stiffer axle tends to be used in the higher grip conditions. A softer axle when you're trying to generate more grip.
The standard-length axle seems to work in the cooler conditions when we talk about different axle sizes. Our cadet karts generally have a 30 mm axle and the full-size senior chassis come standard with a 50mm axle.
The cadet classes using the smaller axles, there's less tuning when it comes to those axles. They spring less. There's just not enough axle to really have that spring effect. So, between soft, medium & hard axles, they have different characteristics, but less effect than the larger size axles.
That's some basic advice about axles. I would always try have a soft, medium, and hard axle at your disposal so you can tune to the changing track conditions. Start neutral then depending on what you’re experiencing, adjust accordingly.
But if you need to know more about kart set up, then we have a dedicated kart set up program that discusses more than just axles. We explain when to use magnesium or alloy rims, what ride height adjustment does, seat positions and more.