Pro Tip

Answers to karting’s most frequently asked questions

Pro Tip: How to Change an Axle

Technical Director at J3 Competition and COMPKART, Justin Stefani, shows you the best steps to remove and install your rear axle.

How can you remove or install the rear axle quickly and safely without damaging your equipment?

When removing or installing your rear axle you can run into problems with it becoming bound up, which can cause damage to your axle and inside your bearings if you try to remove it improperly. Forcefully hammering at the end of an axle may seem like the easy solution, but that can go a long ways in ruining your axle and your bearings.

Removing the rear axle

Removing an axle begins with loosening your exterior rear hubs. That includes both your wheel hubs and your sprocket hub. Whether or not your sprocket is fixed to your sprocket hub or not, you'll need to loosen the bolts to help the hub slide off the axle without any bind.

Now that you've successfully removed the exterior hubs, wheel and sprocket, now you'll need to move to the interior hubs and prepare them for the dissasembly process. Two things that you need to with the brake hub are loosen the bolts that fix the rotor to the hub, as well as loosen the bolt that fixes the hub to the axle.

At this point you have removed all external hubs and loosened the brake hub and brake rotor. Now we will remove the set screws that fix the axle to the bearing. There are three set screws with each bearing, each of which need to be completely removed and placed in a safe spot so you don't misplace them. Your third bearing (middle bearing) may or may not use any set screws; we are not using them in our video.

The final step in our disassembly process requires a small file and a rubberized hammer or dead blow hammer. We'll use the rubberized hammer to gently knock the axle away from the brake side in order to get the set screw marks just oustide of their bearing. Once just outside of their bearing, we'll use our small file to file down the set screw marks. It's especially important on the brake side so that it doesnt mark your brake hub, inside of the bearings, and the axle itself as it travels through.

It's important to note: if you are running a third bearing, it is recommended that you crack loose the bolts fixing it to the chassis.

You should now be able to safely pull your axle through, removing your brake hub and, if installed, your water pump belt in the process.

Installing the rear axle

If you are running the third bearing, you'll need to remove it for the initial install process. This will help you align the outer bearings with each other via the axle when you slide it through.

Begin by sliding your axle through the engine side first. As you go to push it through the brake-side bearing, feel for tightness. If it's tight, it could mean misalignment or a bur on the end of the axle. But because we've already filed down the set screw marks, there should be no bur on our axle. At this point, pull the axle out and we'll try pushing it through from the brake side.

From the brake-side bearing, stop your axle just before it meets up with the engine-side bearing. If it appears aligned with the bearing, go ahead and push it through. If not, go ahead and lean on the axle a little bit and try to get the bearing on the brake-side to align itself better with the engine-side bearing. If the bearings are aligned, your axle should slide through without any hesitation.

Now that our bearings are aligned, you can go ahead and re-install the third bearing if you're using one. You should also install your external water pump belts and brake rotor and sprocket at this time. Don't forget your brake hub keyway!

At this time your axle is pretty well fitted. You'll want to make sure your axle is centered to the chassis. You'll want to take a measurement from outside the bearing cassette to the outside of the axle on the same side. That measurement should be equal on both sides. Luckily for us, we've installed our axle previously so it has set screw marks from the first time. We'll align our set screw marks with our set screw holes and reuse them.

To finish the job, go ahead and fix your external hubs back on where you had them.

In Summary

Removal

  1. Take your time
  2. Loosen the proper items on the axle: hub bolts, sprocket hub bolts, third bearing bolts if applicable, brake rotor bolts that fix it to the hub
  3. Gently tap the axle away from the brake side until your set screw marks are just outside of their bearing
  4. File down your set screw marks and any other burs you may see
  5. Pull your axle through, removing the brake rotor and keyway, and possibly a water pump belt in the process.

Installation

  1. Remove your third bearing if applicable, and align your exterior bearings with each other via the axle.
  2. Reinstall the third bearing and water pump belt if applicable, as well as the brake rotor and keyway.
  3. Center your axle with your chassis by measuring from the outside of your bearing cassette with the outside of the axle on the same side.
  4. Reinstall your external hubs