I bought one of these HD axle kits from gasbike with the freewheel for my 4 stroke engine bike. The first freewheel unscrewed itself after 5 minuets of riding. I got a replacement and the same thing happened again! I put it together correctly, the issue is the freewheel unscrews from the inside, causing the internals to be exposed and the bearings to fly out every which way. This is very frustrating, why is this happening and how can I fix the issue? Thanks in advance.