A jackshaft is an essential part of a lot of machines and works to assist in transferring and synchronizing the force of a machine that’s rotating.

What’s A Jackshaft On A Go-Kart?

A jackshaft, which can also be known as a countershaft, is a part in common machines that are utilized for assisting in transferring and then synchronizing the force of any rotating machine part. It is a torque converter, in brief.

Jackshafts are created as a shot stub that has bearings on both sides and comes with two pulleys, a few gears, and possibly cranks that are attached to it to assist in transferring the rotational power.

A jackshaft is a terminology that’s somewhat blanket-like as it can apply to any shaft that’s utilized for transferring power and transmitting it from a drive shaft that’s moving to some other shaft or some other part of the machine or engine.

The initial occurrence of the jackshaft that was recorded goes back to New England and water wheels and even stationary steam engines in a few situations.

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What’s The Purpose Of A Jackshaft On A Go-Kart?

With the customary go-kart setup, the engine creates mechanical power that turns a crankshaft.

The crankshaft transmits the rotational power to the axle with the usage of a roller chain and two sprockets. The disparity with the go-kart jackshaft setup is that in between the axle and the crankshaft, there’s a jackshaft with two added sprockets.

It denotes that the crankshaft transmits the rotational power to the jackshaft, in place of directly to the axle. A jackshaft then transmits the rotational power to the back axle with the usage of the two extra sprockets and a chain.

By now, you are perhaps wondering what the jackshaft’s purpose is on the go-kart. Well, there are numerous reasons why a few go-karts run the jackshaft setup.

The main cause is that it permits a go-kart to work without the axle being aligned with the crankshaft.

It denotes that the power source can be at a diverse location and both axle sprocket and crankshaft sprocket don’t have to align.

Moreover, you will be utilizing a jackshaft if you’re running the torque converter on the go-kart.

The torque converter’s driven unit acts like the jackshaft, as the two pulleys are connected through a belt and the driven unit with the back axle sprockets with the chain.

A jackshaft isn’t needed for racing karts but is meant for homemade go-karts or off-road go-karts that are not capable of aligning the crankshaft with an axle directly or have the torque converter. It is more common in snowmobiles and motorcycles.

Because of the wider wheels and narrow frames, they require the jackshaft to make the alignment. As said, the same can be said for a few off-road karts.

What Machines Utilize Jackshafts?

  • Factories
  • Snowmobiles
  • Motorcycles
  • Farm machinery

There are a lot of diverse machines that utilize jackshafts for running and operating.

Jackshafts are frequently utilized in farm machinery for assisting power accessories that aren’t part of the main device and that can’t run directly off of a power source.

With farm machinery and tractors, the jackshaft is utilized for moving power from the motor to such additional accessories like the disking wheels that are utilized for assisting in tilling up the soil for planting.

Such accessories are gonna require power for running, but they’re not necessarily gonna be capable of drawing directly from the engine; that’s where the jackshaft assists.

Motorcycles also usually utilize jackshafts. The jackshaft in the motorcycle needs to do with the engine’s position. By utilizing the jackshaft, the motorcycle creator can then move the engine and put it where it’s gonna assist the overall working of the motorcycle rather than putting it so that it can send power to the wheels.

By utilizing the jackshaft, a builder can put the engine in the frame’s middle where it’s centered and where the bike can be balanced better rather than needing to place it right by the wheel that it’s gonna be driving.

It makes for a better ride, a better bike that can be simpler for maneuvering and simpler for riding overall. Jackshafts provide a little freedom when it comes to the overall making.

With snowmobiles, the jackshaft assists in making it possible to put the engine and the power where it’s gonna be top protected and best fit, but still be capable of delivering power to the other components of the snowmobile where it’s required. The engine in the snowmobile is in the back, with the drive belt being situated on one side.

The jackshaft then runs across a snowmobile and then attaches to the driven gear and the drive gear, then connects to the track.

The jackshaft permits the engine to be put where it’s gonna be protected but still provides power where it has to be.

Jackshafts are also usually used to assist in delivering power to individual stations in factories that utilize an assembly line-style design.

It denotes that if you work in a factory that has a central power source or the central machine, they may utilize a jackshaft to power every individual station that is utilized off of the assembly line.

It permits the factory to make stations that aren’t unavoidably aligned with the main power source.

Should I Install The Jackshaft For A Go-Kart?

Well, the answer to it actually depends. As you know, the main purpose for running the jackshaft setup, there are also other advantages.

It also provides you with more flexibility to gear the sprockets, as you have a total of 4 in place of two.

Secondly, because the jackshaft acts as the pulley, it decreases the physical stress on the chain and sprockets. That’s because, in place of 3 components, the load is now spread across 6.

However, do not forget that the additional friction denotes that the go-kart will face a minor power loss. Additionally, the increased moving components denote more maintenance and more things that could slip up. If you are creating a go-kart yourself or working on an off-road kart, I recommend that you only go for the jackshaft setup out of necessity.

If you have no other method of aligning the crankshaft using the axle, then you ought to contemplate it. It does need a little planning and customization, but it is an effective way of aligning the power source using the axle.

To reiterate, racing karts don’t need a jackshaft, as they are laid out in a way that facilitates the alignment between the axle and the crankshaft by the usage of 2 sprockets and a chain (or a clutch or torque converter).

How To Calculate The Jackshaft Ratio?

If you’ve decided to opt for the jackshaft setup for the kart, you will have to compute the jackshaft ratio.

In other terms, the jackshaft ratio is actually the sprocket ratio between all four sprockets. Remember that in place of the customary two sprockets, you now need to account for 4.

Jackshaft Ratio: Ratio A x Ratio B

  • Ratio A: Jackshaft’ Teeth In Sprocket / Crankshaft’s Teeth Sprocket
  • Ratio B: Axle’ Teeth In Sprocket / Jackshaft’ Teeth Out Sprocket

For calculating the jackshaft ratio for the kart, you have to calculate both sprocket ratios and multiply them.

You begin by dividing the number of the jackshaft’s teeth by the number of the crankshaft sprocket’s teeth.

Let’s name it Sprocket Ratio A. Then you divide the axle sprocket teeth by the amount of jackshaft out sprocket’s teeth. Let’s name that Ratio B. Now just multiply Ratio A and B for getting the final ratio.

Jackshaft Description:

  • Axle Sprocket
  • Jackshaft Out Sprocket
  • Jackshaft In Sprocket
  • Crankshaft Sprocket

If you’d want to find out more about sprocket compatibility and chain sizes, make certain to check out the kart chain size chart.


Upon inspecting a kart jackshaft kit, make sure that you know everything that is comprised.

It is quite a hassle getting only components of the parts and then requiring sourcing the components that were not comprised.

You ought to make certain that the jackshaft kit comprises at least two bearings, two sprockets, two locking collars, two bearing hangers, one jackshaft, and two keys.

There are numerous jackshaft kits that have spare parts like mounts, plates, and bolts that are not needed if you’re opting for a simple jackshaft setup.

Make sure that you also have the tool kit accessible for installing the jackshaft, as none of such kits have the needed tooling.

One thing folks frequently forget is that the current setup is most likely running on one chain.

With the jackshaft setup, you will require an additional chain that connects from the jackshaft to the sprocket on the back axle. Make certain that you know that before installing the jackshaft.


When choosing a jackshaft kit for the kart, you ought to always make sure that the parts are made of the best quality materials.

Frequently the product page has details as to what the parts are made of. If that data isn’t accessible, you can always refer to the company and check if they’re trustworthy. If that is also not accessible, you can check out online reviews.

The majority of the parts are made of alloy steel with a hardened surface for withstanding forces and wearing over time.

The only more compound part that cannot be gauged well from images is the bearings.

They ought to be top-quality precision bearings, so make sure to test them first before installing them on the kart.


Jackshaft kits for karts are inexpensive. A basic entry-level kit having the six most essential parts will cost you about 40 dollars to 65 dollars.

A more professional kit can cost you about 80 dollars to 150 dollars, depending on the brand and the number of parts.


When it comes to the jackshaft kit conditions, you can either purchase them used or new. I highly suggest purchasing them new, as they’re comparatively low-cost and you are assured that the parts are all in good condition and in good shape.

If you are on a shoestring budget and are searching for used jackshaft kits, it is a great idea to message the seller and ask him about the current wear and the condition of the parts.

The final thing you desire to do is to purchase a used jackshaft kit that’s unusable, or that’ll only last a short while.

How To Maintain A Go-Kart Jackshaft?

Maintaining a kart jackshaft is really important, as they’re responsible for transferring the rotational power from your crankshaft to the back axle.

If the jackshaft is not well maintained, it can cause a loss of power and potential kart damage if the chair breaks. It is therefore suggested to check the jackshaft each time you do the regular kart maintenance.

The first thing you ought to check is for wear and tear. Check for wear on the sprockets and chain. You ought to also frequently apply lubricant on the chain, to ensure it runs smoothly.

A clean chain lubricant will do. If the sprockets and the chains are worn, replace them with new ones.

I always replace the chain and the sprockets at the same time, as they’ve similar wear rates on my kart.

As jackshafts have closed bearings, you will simply have to spin the jackshaft to make sure that they’re still running smoothly and aren’t damaged.

You ought to also check that the jackshaft moves easily and there is not any obvious noise.

Go-Kart Jackshaft Maintenance Summary:

  • Make sure that the sprockets are in good condition
  • Check chains for any wear
  • Lubricate both chains appropriately
  • Make certain that bearings run smoothly
  • Make sure that there are no obvious noises


Hopefully, you have enjoyed this guide on go-kart jackshafts. As you are aware already, jackshafts on karts are not that common, but they do have an application.

If the axle sprocket does not align with your crankshaft sprocket, the jackshaft is an outstanding solution.

They also provide some other advantages, like less stress on the sprockets and chain. If you choose the jackshaft setup, I highly suggest choosing the go-kart jackshaft kit.

It’ll really simplify the part selection and save you much time that you ought to spend on installing it.