Had my axle move twice during my last outing. It moved part way through the day to the point the rotor face was contacting the inside face of the caliper and dragging. Got out the allen wrenches and put things back where they belonged, then it move again, albeit, much less. I didn’t notice the second movement until the kart was on the stand Monday night.
My question is how tight should I be torquing the bearing set screws on the axle. Is this an item to check every single run? I did about 75 laps over about 8 sessions that day.
Depends on the type of axle, thin wall or thick. For a thick walled axle, position the axle where you want it, remove the grub screws from the axle bearing on one side of the kart. My preference would be the brake side. Drill the axle through the grub screw holes and run a tap that is the same size as the grub screw, through the axle bearing and into the axle. Get longer grub screws and Loctite them in. On the other hand, for a thin walled axle, use a locking collar on both sides of one of the axle bearings.
They do need to be tightened well. When I was really into changing axles a lot, I used to strip out an allen wrench from time to time, but it kept them from moving. I did the Loctite thing for awhile as well, but eventually I just got them tight and didn’t need to mess with it.
My axle was shifting during this past race weekend and while doing so, it was tighening up my chain to the point where there was absolutely no slack in it. My kart’s handling was also all over the place too. The Ny-lock nuts I put on at the start of the season and were unable to keep hold. I replaced all 6 nuts and also instead of regular washers, I’m using lock washers as well- got them nice & tight and the problem has not re-occured.
I never felt comfortable getting the set screws that tight, always thought that it couldn’t be good for the axle. Use axle collars, they work great. Next time you replace a bearing, look into SKF Concentra bearings. They are pricey, but worth it in my opinion. No more set screws to mark up the axle, and when it’s cleaned with brake cleaner and properly installed it will not move. I only have 2, and I use a regular bearing in the middle.