Tech Tuesday: Axles

It all starts with the right preparation – checking your kart is safe and that nothing is going to impede your rapid progress to the front of the pack. Starting with the axle assembly we’ll go through each element of a well-maintained kart.

This is a key stage of kart preparation done by professional teams between races and test days, and sometimes even on a Saturday night. Mainly you’re checking that the axle assembly is safe, and it also has an effect on performance.

1. This is what the axle looks like at the end of a weekend. It’s dirty and a little bit rusty in places. The scratches are from the brake disc and sprocket carriers and also grub screws. The whole point of removing the axle is to make sure first of all there’s no cracks in it hidden inside the bearings and to clean it and check it over.

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2. The whole point of removing the axle is to make sure first of all there’s no cracks in it hidden inside the bearings and to clean it and check it over. First remove the grub screws as this image shows



3. Zip tie the brake pedal to keep the brake disc in place while removing the axle.



4. Removing the axle with a heavy piece of steel machined to fit inside a 50mm axle with 2mm wall thickness.



5. The brake disc has been retained by the zip tie on the pedal as the axle is slid out. at this point you can remove the rubber bands for the water pump belt and the water pump pulley if used.

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6. Taking the brake disc and sprocket carrier and cleaning out the inside of them. This helps when you come to put them back on.



7. Photos of the carriers before and after they’ve been cleaned up inside. It’s also a good time to check the retaining bolts are in good condition as sometimes they can be rounded off. Some people lubricate the bolts which helps them get a tighter purchase.




8. The same process for the inside of the bearings. This is an especially good idea when it comes to reassembly and if you’re cleaning the axle you might as well do the bearings as well.



9. This is after polishing the axle. We put the axle in a lathe and just got some 250 grit wet and dry paper to polish the axle so that rust spots and blemishes were removed. You don’t have to use a lathe, it can be done by hand quite easily but a lathe speeds it up. Some people have made clever axle polishing rigs using bearings and bearing carriers, driven by a cheap power tool.


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10. The axle, brake and sprocket carriers and the hub should all just slide back together without any undue force. The most important thing to do is to apply some medium strength or high strength threadlock onto the grub screws to make sure they don’t come loose to cause the axle to move when you’re driving around. It’s good practice to line up the original grub screw marks on the axle with the grub screw holes in the bearings. This helps to reduce the number of stress points on the axle where cracks can form. It also makes it easier to remove the axle.




This article was originally published in Karting Magazine in December 2015


Like this article? Then read more Tech Tuesday here:

Tech Tuesday – Chassis straightening

Tech Tuesday – Top 5 setup tools