18-08-2021, 08:48 PM
Derek are you sure the rear bearing is undersize, or has the bearing simply been spinning on the shaft and worn it down?
It's a not uncommon situation. The traditional fix was to dot-punch the shaft all over the mating area and this would raise spots locally to provide some measure of grip. A more modern solution is to build up the shaft by metal spraying, though this generally entails machining off some material to provide enough thickness. Another possibility is to machine a little off and sleeve the shaft. Some just slap it together with some Loctite - depends just how loose it is.
If you choose to follow the latter course, for heaven's sake make sure you are able to remove the bearing from the shaft again! Keeping in mind that you may have to do so with it in the crankcase where it's very hard to apply much force.
Before doing any such thing or spending more money I would suggest crack testing the shaft and inspecting it carefully for any other defects. You might very well do better just to find another shaft, they are not usually much money.
It's a not uncommon situation. The traditional fix was to dot-punch the shaft all over the mating area and this would raise spots locally to provide some measure of grip. A more modern solution is to build up the shaft by metal spraying, though this generally entails machining off some material to provide enough thickness. Another possibility is to machine a little off and sleeve the shaft. Some just slap it together with some Loctite - depends just how loose it is.
If you choose to follow the latter course, for heaven's sake make sure you are able to remove the bearing from the shaft again! Keeping in mind that you may have to do so with it in the crankcase where it's very hard to apply much force.
Before doing any such thing or spending more money I would suggest crack testing the shaft and inspecting it carefully for any other defects. You might very well do better just to find another shaft, they are not usually much money.