Flower nut spun out stripped both nut and shaft --Why ?

[digital_life]

Recently my clutch stopped working and after a quick inspection I noticed the flower nut had spun out and the only thing that stopped was case.

This motor had over 6 thousand kilometers (3728 miles) and I regularly took the covers off to inspect and adjust the flower nut so I am fairly certain that all was put back together properly.

I actually have 2 question's
1. Why did this happen is it common
2. Do you know of any good videos to remove and install another shaft without splitting the case since I have a couple of these motor's that do not run.

Pictures

 

[wolframore]

Did you have the locking screw on the flower nut?

 

[digital_life]

yes I did, When I took the cover off the screw was still in the right place and flower nut was above it defiantly not the way I had installed it -- Its like the flower nut spun and the screw did not do its job.

My guess was that when I pulled the clutch the plate stayed down and just the flower nut moved and it all went to hell after that.

 

[wolframore]

The only way that it could happen is if the woodruff key #12 in the diagram sheared off or was missing or something else broke that allows it to spin freely, I’ve never seen it happen but not sure if Ive seen one with such high mileage.

Pull the clutch off. You should be able to replace without splitting the case. I would replace the bearings and anything else that looks worn.

 

[mony0_3]

Being that the shaft comes as an assembly, I had to split the case to replace mine.

 

[wolframore]

The clutch bearings pull out from the outside. No need to crack the case. You may need to press the shaft out. Don’t use a hammer. Also fully disassemble everything off the clutch shaft

 

[Chainlube]

Follow, https://motoredbikes.com/media/albums/teardown-chinese-ht-49-80cc-engine.808/

 

[Axl Myk]

The clutch bearings pull out from the outside. No need to crack the case. You may need to press the shaft out. Don’t use a hammer. Also fully disassemble everything off the clutch shaft

Yeah, that.
I had to use an arbor press to push the shaft and one bearing out one side, then the other bearing comes out the other side.

 

[Cavity]

Did I read that right? You damaged both your shaft and your nuts? I wish you well.

 

[digital_life]

The only way that it could happen is if the woodruff key #12 in the diagram sheared off or was missing or something else broke that allows it to spin freely, I’ve never seen it happen but not sure if Ive seen one with such high mileage.

Pull the clutch off. You should be able to replace without splitting the case. I would replace the bearings and anything else that looks worn.

View attachment 100636

I will keep my eye on it when I get around to taking it apart, Right now I am too busy with other things one of which is breaking in a new motor.