The 3 Types of Go-Kart Axles
Axles are a very big part of the way the kart is set up because there is no suspension on the kart. The axle equally delivers power to the go-kart’s rear wheels. The axle is what springs the go-kart off the corner. There are three different axles: Medium (or neutral), Soft, and Hard.
Medium (Neutral) Axles
I’ve driven on many different go-karts and raced major races on at least six different chassis. The majority of the time, around 75% of the time, you run the medium or neutral axle. It tends to be the best performing axle overall, as it helps the go-kart off the corner more effectively. It also adapts well to changes. It responds and adjusts well to different conditions on the track.
If you ever get lost trying to determine which axle to use and you’ve tried different types, the best bet is to put the neutral axle back in and run with it.
Soft Axles
A step down from the medium axle is the soft axle. The soft axle is a little bit different, and it does give the kart a different feel. The soft axle allows the go-kart to gain a lot more braking stability as it enters the corner.
It feels like the chassis digs into the ground and kind of squats a little bit in the braking zone. This can allow you to feel more confident in the brakes and charge the corner harder. As you get into the corner, the axle doesn’t lift as high as it would with the medium axle, but you have a lot more grip entry to the center of the corner. You can carry a lot more speed into the center of the corner.
The problem with the soft axle is when you get to the center of the corner, you don’t have that spring-off corner ability that you get with the medium axle.
When you get into the center of the corner, there’s a lot of load on the go-kart. You want to have the go-kart spring back once the load is being released, center off the corner. With the softer axle, it tends to absorb that load well, but it doesn’t release its center off the corner. You tend to have this give and take where you gain on entry. You don’t have that same spring-off corner that you do with the other axle. It can tend to lead to bogging or other similar issues. If the kart is bogging off the corner because of the chassis, it’s probably time to switch the axle because the kart is too soft for the conditions that you’re driving.
Hard Axle
One step up from the medium axle is the hard axle. This one is a little bit different because you lose braking stability going into the corner. The way I’ve always pictured it is that the softer the axle, the more the go-kart works. The harder the axle, the more it works the tire.
When you go to a hard axle, you lose that braking stability on the entry to the corner, because there’s not much digging into the ground. It’s a hard axle, so you skate a little bit into the corner.
When you go from the entry into the center of the corner, it tends to lean over on the sidewall of the tire a lot better, and you get more hike out of the axle on the inside rear tire. That helps with rotation, and it helps you get the kart pointed straighter.
It makes the kart a little freer on entry into the center of the corner and center off, you lose a little bit of that stability that you had out of the softer axles. The benefit of the hard axle is you still get that spring-off corner that you lost with the softer axles.
Each axle has positives and negatives to it, and that’s why many kart racers end up on the neutral axle. From the Birel to the Tony Karts to AM Racing kart that I drove, the PCR. The best axle is normally the standard axle that came in a go-kart because it works in 75% of the conditions that you’re racing. It works more effectively overall, and you still have a good spring off the corners without sacrificing that grip that you get as you enter into the side of the corner.
Axle Length: Short vs. Long
Another setup for axles is a short axle versus a long axle. You may be asking “What size axle do I need for my go-kart?”
With a short axle, you tend to lose braking stability. When you go into a corner on a shorter axle, the kart is more responsive. But because it’s so responsive the kart reacts on the brakes and it wants to step out, it’s always on edge. It feels like this because as you get into the center of the corner the axle will raise off the ground fast and lift into the center of the corner.
With the short axle, it can sometimes lift too fast and throws the rear around. Or it goes up too high, and when the axle wants to set back down, it sets back down too hard and that throws the rear around. These axles normally work well around tight tracks, where you can kind of get the kart pointed quick or fast. For instance, 90-degree corners – quick point and your back of the power. Those are where it normally benefits having a shorter axle.
When you go to the tracks with longer, sweeping corners, you don’t want a kart that points super quick and is “darty”. You may want to go to your longer axle or your standard axle. The longer axle gives you more braking stability. You get less hike initially out of the tire from entry to the center of the corner, and you get a little less rotation out of the go-kart. It’s going to be a lot lazier, and it is going to take a lot longer to get this bigger axle around the track.
That is a basic rundown of the types and lengths of axles that you can modify on your go-kart setup!
