I picked up a resurfaced flywheel from a shop in San Jose, it always made bad sounds when starting. I pulled it off recently and found that the outer ring gear was loose. I tried to take it off and sure enough, it came right off.
What was holding it on in the first place? Just pressure?
My guess is that the flywheel was overheated at some point and the flywheel expanded, then contracted.

 

its just tack welded.. mine broke off too just like a month ago. boooo