Gng kit shaft problem

My gng was good at first.
MY setting is 19cells battery(fully charged 77V) and max amps is 38amps. So I used 2900w on my gng kit.
It's chain drive kit of gen 1.1.

But some time I had a trouble. When I took 6~8 spd sproket, freewheel moved backwards and sounded tapping like photo.
I can really see moving.

But 5~1spd is good. no sounds and not move. I think maybe steel axle is very weak and it can't hold up the motor torque then bended.

So... what do I do for not moving shaft ???

The stock freewheel is weak. I don't know of any 12T freewheels that are strong. There are several good freewheels to choose from that have 13T. Read this thread:

http://endless-sphere.com/forums/viewtopic.php?f=28&t=46891

Your kits front end is moving to the right under torque as on any of them with a less than super tight front mount. The kits front (down tube)mount allows the entire kit to flex greatly at high torque levels. I went to a narrow bottom bracket on mine and had to shorten the jack shaft several times before finding the root cause of the problem. My crank arm hit the shaft end under extreme torque before I made my cradle front mount. The clicking sound you are getting may be a few other issues possibly if the shaft has enough clearance. Freewheel may be loosening up/ starting to fail or the freewheel /hub may be coming apart at the welds. May fail catastrophically at some point as it has for several ES members if so. Also the Jack bearings will make noise also if dry or loose.

At that powerlevel you could benefit from a torque-strut like i did on my Stinky. (Sorry the bike is upsidedown in that pic)


The freewheel should hold up fine as long as it doesnt unscrew itself. Lock the outer washer with a spotweld or something.

spinningmagnets said:

The stock freewheel is weak. I don't know of any 12T freewheels that are strong. There are several good freewheels to choose from that have 13T. Read this thread:

http://endless-sphere.com/forums/viewtopic.php?f=28&t=46891

Click to expand...

yeah. thx for reply.
I think the steel is very weak.

christerljung said:

At that powerlevel you could benefit from a torque-strut like i did on my Stinky. (Sorry the bike is upsidedown in that pic)

The freewheel should hold up fine as long as it doesnt unscrew itself. Lock the outer washer with a spotweld or something.

Click to expand...

oh.. thx for help. It really prevents from bending weak steel axle.
Can I know how disassemble the freewheel. I opened ball bearing but I couldn't detach freewheel from steel axle. T.T

You might need a pulling-tool or try the Dirty way, lift the whole bike in the freewheel and tap with a hammer on the shaft. Be carefull not to damage the threads.