Titanium Jack Shaft, Junior Sprint

Fits Hyper and D1 style Junior Sprint engine mount.

10-9/16" long x 3/4" diameter. 5/16-24 threads on each side. 2-1/4" keyway on one side and 3-3/8" keyway on the other side.

If you have an issue with the shaft gulling up under the bearings, it most likely is due to the inner race of the bearing spinning on the shaft. On Junior Sprints, most racers don't like to preload the bearing, they leave play left to right (1/32") and don't run a spacer in the inside of the housing between the bearings the way a normal bearing application is supposed to be setup. Bearing manufacturers' would yell at us for the way we have these bearings in use, the inner race is ALWAYS supposed to be clamped in some way so it doesn't spin.

No one wants to do that so they run them loose to get less drag. Although under load it actually makes no drag difference, everyone wants to spin the shaft and watch it spin for two minutes before it stops. So, a couple things to help keep the inner race from spinning on the shaft in our case, take the seals out of the bearings and clean them every race, also use very light oil or grease on the bearings. Use the M2 bearings, those don't need any oil (but you can oil them for longer use), but still need cleaned.

Also, the belt should have 4-6 pounds of preload on it. This is how those belts are designed to be used. This also keeps load on the bearings which helps keep the inner race from spinning. Don't run the belt too loose.