Most machines use (2 bearings,) the inner is closest to the drum,has the biggest hole in center for spider shaft the outer has the smaller hole and is closest to the drive wheel.To measure a bearing for size you need to measure the outside diameter (OD) and inside diameter(ID) of BOTH bearing.4 MEASUREMENTS WILL BE NEEDED as the OD may NOT be the same size front and back,The best way is a digital caliper,this measures internal/external very accurately.
wirecutterman, March 2009