Go-karts are relatively simple machines. Karts have small engines and are rear wheel drive, but they work differently from cars. You might have heard the karting community talking about live axles, and you might be wondering what a live axle is.
The live axle on a go-kart refers to the rear axle, which is the one that has power delivered to it and is used to drive the kart forward using a clutch, chain, and sprocket. Live axles are used in karting because they are cheap and easy to maintain, which is ideal for motorsport beginners.
Live axles are completely different from differentials that are found on cars. There are some important differences between the two both in terms of how the vehicle can be set up, and how the driver needs to control their vehicle. We take a closer look at these below.
Go-Kart Live Axles Explained
On a go-kart, the live axle is an axle that equally delivers power to both of the rear wheels. This is also known as the driven axle, as it is the axle that receives power from the engine and converts it into forward movement.
The live axle on a kart is a long steel shaft that spans the entire width of the kart. It goes at the rear of the kart, with the left and right rear wheels that attach to the end of it. On the engine side of the axle (usually the right-hand side in karts), a sprocket will be attached to the axle right behind the wheel hubs.
The sprocket is connected to a chain, which in turn connects to the clutch on the engine. When the engine is fired up, the crankshaft turns the clutch, which will pull the chain and cause the rear axle to rotate. This is a basic explanation of how a go-kart engine and axle connect to make the kart move forward.
On the left-hand side of the axle, there is a brake disc. The brake discs are centered between two brake pads and brake calipers, with a hydraulic cable that runs all the way to the piston on the left-hand side of the driver’s seat. This piston connects to the brake pedal, which is what will be used to slow the rear axle down and produce stopping power in the kart.
Advantages & Disadvantages Of A Live Axle
Live axles are completely different from any other system that you would find on road cars, or even racing cars. There are both advantages and disadvantages to having a live axle installed on a vehicle, and in terms of karting, the advantages outweigh the disadvantages.
The advantages of a live axle are:
- Faster acceleration
- Less maintenance
The disadvantages of a live axle are:
- Poor cornering ability
- Bumpier ride
- Prone to damage
Advantages Of A Live Axle
The live axle on a kart connects both of the rear wheels together. This means that the power displacement is equal between both of the rear wheels. Unlike with cars, the left and the rear wheels will spin at the same rate since they are connected, which means that power delivery is equal to both wheels.
However, this does not necessarily mean better traction. Differential systems can control wheels individually, which allows one wheel to spin slower than the other to find better traction. In a straight line, a live axle can deliver the same amount of power on both sides of the kart, making it rapid when launching out of corners.
Live axles are much cheaper systems because they are one long steel axle with no electronic systems attached. All you need is the axle, as the sprocket, wheel hubs, brake discs, and everything else is separate. Karting axles can cost you between $100 and $300 depending on where you’re buying them.
One of the main factors that make karting such an attractive sport is the cost effective nature of it. Having a live axle system on the kart allows drivers and teams to keep their costs down by using a simplistic system rather than a complex electronic one.
Since the live axle system is so simple, it’s also much easier to maintain. In fact, there is almost no maintenance involved in a live axle. Most of the maintenance is focused on the parts attached to the axle such as the sprocket, brake calipers, and wheel hubs.
The axle itself requires no maintenance at all. However, it does need to be checked for cracks and wear every now and then. This is one of the disadvantages of a live axle system that we will cover shortly. Overall, it’s one of the parts on a kart that usually requires nothing but a quick clean every now and then.
The key to making a kart fast is keeping it lightweight. Racing karts weigh less than the average adult, which is why they are so fast and nimble, even with little horsepower. Live axle systems are much lighter than any other driving force on a vehicle. The weight of a kart’s rear axle is between 2 and 5 kilograms (4.4-11 lbs).
This minimal amount of weight being added to the kart helps to keep the overall weight of the kart down while ensuring that it has a strong form of delivering power to the rear wheels. This makes a live axle the ideal solution for a go-kart.
Disadvantages Of A Live Axle
Poor Cornering Ability
Live axles come with some serious drawbacks in the cornering department. With both wheels spinning at the same rate and having an equal power delivery, you will find that karts slide around a lot more, no matter how smooth you try to be with the steering and the throttle. The live axle system is the reason karts often drift through corners.
The outside wheel naturally needs to travel a further distance than the inside wheel. In an ideal world (with a differential), the outside wheel would turn faster than the inside wheel to keep up with it, creating a tighter turning circle without the tires losing traction and grip (causing them to slide across the surface of the tarmac).
That’s not possible with a live axle system because the rear wheels are attached to each other, which means they will always be rotating at the same speed. However, karts have an extremely flexible chassis, which allows the inside wheel to lift in the air under high cornering forces. When this happens, the outside wheel can control the pace, and it allows the kart to turn tighter and bite into the tarmac more.
This effect is known as jacking, and in karting, you’re always looking for the perfect “rate of lift,” which refers to how fast the inside rear wheel lifts off the ground. Perfecting the jacking effect and the rate of lift will allow your kart to corner faster with a live axle system.
Karts are incredibly close to the ground. When you’re in the kart, you can often feel the bottom of the seat scraping the tarmac. This is something that I often experienced when racing at the Bahrain International Karting Circuit, which has a lot of elevation changes through fast corners. It might not sound great from inside the kart, but the damage being done to the kart is minimal, and there is no way around it.
The live axle system prevents the kart from lifting and dropping with bumps in the tarmac (there are no springs or dampers), which means that you will feel every bump that you go over. Having a live axle system also sends more shockwaves through the kart because of its rigidity, so if you ever drive over a rumble strip kerb, you’ll know about it!
Prone To Damage
Because live axle systems are so rigid and stiff, they can also be prone to damage. If you hit the kerbs too hard, you can send a lot of shock through the steel axle, which will cause damage to it over time. There have been many cases of axles snapping in half or breaking into pieces even while the kart is still moving.
This is something that I actually experienced in just my second karting race. After buying a second hand kart, I was racing at a street circuit where the track limits were marked by traffic cones. Lap after lap I would get my wheels onto the edges and corners of the cones, bouncing over them as I tried to make use of every inch of the track.
However, just before starting the final lap of the race, the rear axle snapped in half on the exit of the final corner. It’s a helpless feeling as you slowly grind to a halt on the side of the track with no brakes or throttle to help steer you out of the way.
KEY TIP: Always avoid heavy impacts with a live axle!
You should inspect your axle for any damage or cracks every now and then. Oftentimes the cracks form on the inside of the axle, which means that they are impossible to spot. There’s also no way of telling if an axle is on the verge of breaking or not, so just monitor it as best you can, and take care of it out on the track by avoiding heavy impacts.
KEY POINTS• Live axles are cheap and easy to maintain
• However, they don’t offer as much traction as a differential would in the corners
• They’re also prone to damage if you take a lot of heavy impacts
Go-Kart Live Axle vs Dead Axle
While a live axle is used to drive a kart or other vehicle forward, a dead axle is simply used to attach wheels to the vehicle. Dead axles are not connected to the engine, so there is no power sent to these axles, which means there is no driving force behind the wheels.
They are simply used to attach the wheels to the chassis, and sometimes used as the steering axle (unless it’s a front wheel drive system). In semi-trucks, dead axles are used to add additional support for the heavy weight that the chassis needs to carry. This is a good example of where a dead axle is useful.
However, karts do not have dead axles. The front wheels are connected to the chassis and the steering rod through spindles. The spindles can adjust the Ackermann of the wheels as well as the camber and toe of the front wheels.
Go-Kart Live Axle vs Differential
Differential systems are different from the live axle systems that you would normally find on a kart. Differentials are capable of controlling the power sent to each wheel on the vehicle independently. This can either be the rear wheels only, front wheels only, or all four wheels, depending on the type of vehicle that you have (rear-wheel drive, front-wheel drive, or all-wheel drive).
The power sent to each wheel is controlled by a computer system that measures how fast each wheel needs to rotate in order to achieve optimal grip levels. It’s a complex system, but essentially it will calculate the amount of traction that each tire has in a split second and adjust the wheel’s speed accordingly.
How This Works
For example, if you’re cornering and the inside tire starts to lose traction because it’s moving too fast, the computer can slow the inside rear tire down, which allows it to regain grip and stop sliding. This system is incredibly clever, and it helps to provide modern cars with an immense amount of grip.
All go-karts have live axles, which is a system that uses a steel axle to connect both of the rear wheels. Live axles are connected to the engine and power the wheels (as opposed to a dead axle, which does not power the wheels). Live axle systems have their advantages and disadvantages.