[Masteryota]

The inside 'threads' are from exactly that, riding on the threaded portion of the spindle bolt. I would say, after you clean up the spindle bolts, if there is ANY question of its strength from the wear of the bearings, then look to replace it. Yerf was known for using grade 5 bolts for the spindles, so they aren't that sturdy from the start. The bearing races should come out pretty easily with a hammer and punch/drift, and replacements are inexpensive, just be sure to specify you want the high speed 5/8" bearings, they are built substantially better than the cheap-o brands. I think I paid $4 each from a bearing store, and were rated at something like 25,000 RPM, don't know what that translates to in MPH, but it seemed ok to me.

Also, welcome to the forum, you will find LOADS of info on the Yerf's on here.