I have a Cat Mini bike Model r4001. I needed to replace drum brake. I bought the 4 1/2" drum brake. It does not fit in the original sprocket hub. So I ordered the 4 1/2 sprocket hub. The mounting holes are to wide to bolt up on the original hub. What hub do I need to purchase to make my new parts work with the orginal wheel? New to this and any help would be appreciated.