Grandson's TSDZ2 coaster brake on a 24x3 felt keeps popping the rear hub cog retaining spring ring off I've replaced it a couple of times but it still happens. The rear cog is a 22t dished, and the rear hub is a modified Shimano CB-E110 with loose bearings. and the front bottom bracket has an eccentric American to BSA for the motor. Does anyone have any ideas? I'm starting to say things he shouldn't hear.

Not sure if it is throwing the chain first when this happens. He can sometimes ride a couple of miles before it does.. I've swapped in a new mid drive, and the shimano is the third rear hub I've laced up. first being a SA IGH 5speed drum brake, that developed problems, then a low rider coaster that had the cog tossing the ring so built up the Shimano replaced the chain the only thing I hav'nt replaced. is the cog. he starts out in PAS 1, and so far has gotten about 100 miles on the bike... This is not my first build having done a couple of 52v Bafangs, a 72v Cyclone, and a toseven dmo2 is waiting in the wings. THIS ONE is kicking my butt.