I'm nervous to cut such an expensive piece of equipment. What's the right way to cut a rear kart axle?
This month we’re back in the shop and looking to cut an axle. You could be wondering why anyone would cut an expensive axle and, believe it or not, there are a few good reasons. If you find that the inside wheel is setting down too soon or you need the kart to rotate better through the center of the corner without taking away too much rear grip, you can benefit from a shorter axle. Let’s make sure you have the tools you need to get started and then we’ll dive into how to cut the axle.
What a shorter axle will provide
- Allow the kart to react quicker in the rear, allowing for more rotation
- Stabilizes kart under braking
- Holds rear tire up longer
- Decreases grip on exit
What you need
- Tape measure to measure your axle and cut lines
- Fine tip marker to mark your cut lines
- Cable tie or friend to apply the brake pedal and keep the axle from spinning
- Saw guide (sold at J3 Competition)
- Vice grips to hold the guide in place
- Either a hacksaw or reciprocating saw (like Sawzall™)
- Half-round file
*You could also use a pipe cutter if the proper blade to cut steel is applied. You would not need the saw guide if choosing this option.
Cutting your axle
Before anything gets cut, you want to check the total length of the axle with a tape measure. Most axles come in at a length of 1020mm, 1030mm, or 1040mm. Now, figure out how much you want to take off in total. Our rule of thumb is 10mm at a time, but you can go in multiples of 5mm and be ok.
After you’ve figured the length you want to take off, you need to apply that symmetrically across the axle. For example, if you’ve chosen to take off 10mm (or 1cm), then you will want to take off 5mm on each side. The reason you need to do this symmetrically is not only for balance issues, but also if you take off too much on one side the axle keyways will no longer line up with your hubs when you align the axle in the center of your kart.
Find a point on your chassis to measure from, most likely your bearing cassettes. It’s critical you use the same measuring point on each side of the chassis. Now, make a mark on the axle where you want to make your cut. In our video we’ve elected to cut 2cm in total, so we’ve made a mark 1cm from the end of the axle on one side and will apply the same mark on the other side.
Before starting any cutting procedures, you will want to keep the axle from spinning. We have applied a cable tie to our brake pedal to keep the brake on while we do our cut.
To make the cuts, you may use a few options. If choosing a pipe cutter, that’s all you will need to make the cut so long as you have the proper blade attached to cut steel. What we’re using is a reciprocating saw, or Sawzall™, combined with a saw guide (or flex cutter) made by J3 Competition. A hacksaw will work as well in place of the reciprocating saw.
You’ll clamp down the saw guide on the axle, making sure you have the cut line in the center of the guide. Now simply place the saw in the guide and make your cut. When you’re finished, remove the guide and you should have a perfectly cut piece of axle left inside the guide. Apply the same cutting procedures to the other side of the axle.
To finish off the entire process, you’ll file down any metal burrs left behind on the axle ends so we can slide on our hubs without any issue. We utilize a half-round file to smooth the axle. The rounded edge is much easier to file an axle than a flat edge. Run the file around the outside and inside of the axle, removing any burrs you can feel with your fingers.
- Check the total length of your axle with a tape measure.
- Figure how much of the axle you want to remove, usually in increments of 5mm or 10mm. Apply that length symmetrically to both sides of the axle. I.e., 1cm removal equals 5mm on both sides.
- Mark both sides of the axle with a fine point marker where you want to make your cuts, measuring from the bearing cassettes.
- Apply brake pedal with a cable tie so the axle does not move while cutting
- Make the cuts using a saw guide with a reciprocating saw or handsaw. A pipe cutter may also be used with a steel cutting blade.