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.
LAD Specialties customer / tony kart / rotax / kt100