CB Hub Too Loose? Too Tight? Stripped?

[LLesmeister]

Hey, folks. I'm new to the forums, and new to coaster-brake hubs. Two of them in our shop are experiencing problems. When I grip the brake bar and try to turn the sprocket, it will turn and kinda click as I turn, and it does it in both directions, which tells me the drive chain won't really engage the wheel when you pedal, and the brake probably doesn't work either. That sprocket will also wiggle just a bit. So I'm thinking maybe the hub's too loose. But when I'm gripping the brake bar to hold the axle still, the wheel turns maybe one or two rotations and stops, and you can feel the bearings grinding a bit, like the hub is too tight. I can't test-ride it, but on the other ones we have like these, that sprocket doesn't wiggle (these are basically kids' novelty bikes, called banana peels.)

I've been watching videos and whatnot for them for a week with no success. I've taken one of the two that I'm having problems with apart entirely, which was helpful for me, but I'm stuck as far as actually diagnosing this problem. Any ideas?

PS, on the one I took apart, I'm not seeing any real wear, pits, etc. These are all new, but they were assembled by...folks who aren't bike mechanics, I guess. So it may have been wrong from the beginning.

[DaveM]

You say the sprocket is "loose". If it moves side to side in conjunction with the axle, it could be loose bearings. But I'm more suspecting that the sprocket is loose where it attaches to the hub itself. In which case, completely unrelated to whether the bearings are loose or tight. Sprockets on coasters are usually held on with a snap ring. I've seen them put together with snap rings that were clearly the wrong size so they were barely locked on to the hub at all. I'd take a look at that.

For bearing adjustment, I like to clamp the axle in a vise and feel at the rim for side to side play. That's the most sensitive way to feel if the bearings are too lose.