How tight is too tight or too loose?

My son had his 5th race weekend this past Sunday. It was the first race where I had personally done maintenance to the kart. I replaced his sprocket (Kid Kart) so everything was loosened or removed off the rear axle.

While testing on Saturday, the brake rotor came loose and the sprocket came loose. On his race final, one of the wheel hubs came loose and slid in on the axel, jamming his throttle and ending his race on the first turn.

I have a history of breaking things because I over-tighten. Any advice on how think about tightening nuts and screws on the rear axle or anywhere else?

Maybe try some loctite blue?

With experience you will get to know the appropriate spanner length and how hard to pull on it. Things won’t work loose and bolts will not shear off.

Not much help ? Well on a kart you will normally be dealing with 6mm, 8mm, and 10mm bolts or Allen screws. It seems that recommended tightening torques are around 10, 25,and 40 lbf. ft. so using a simple torque wrench will get you into the right area. After a bit you will be able to dispense with this and do it by feel.

Checking in my toolbox spanner lengths are

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Continued.Spanner lengths are 5,7, and 9 inches long overall. Allen keys around the same. I think you will find it hard to tighten sufficiently using a T bar key but that may be my weakness!

For wheel nuts I have a single hex. 13mm. socket welded to an extension bar with a 6 inch lever. Check the wheel nuts every time you go out.

I use tubular sleeves on the axle to make sure the hubs etc. do not move.

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Get yourself a torque wrench, and use it - even if you only use it for a while to understand how much force is appropriate for that size fastener. Make sure threads are true and not deformed, only use clean fasteners.

Use other retaining mechanisms:

  • safety wire
  • a thread-locking compound appropriate for how often you might take them on/off.

I blue Loctite everything except for hubs and wheel nuts.