New Planetary gear resistance problem


New member
Local time
12:05 PM
Aug 21, 2023
Norwich UK
Hello all! First time post but long time reader so thanks!

I've had an engwe bike for a couple of months, developed clunky sounds from the motor so my suspicion was planetary gear fail.. Engwe shipped me a whole new motor core so of course I'm hoping I can keep a motor core as back up!

My suspicion was correct, 2 planetary gears showed cracks in them when I opened the motor up.
The new planetary gear set drops on and off the NEW motor core and axle easily enough, but on the OLD one there is a lot of resistance, I struggled to get the original damaged Planetary set off!
I thought originally there could be burrs on the shaft of the old axle so I gave it a good buff with wet and dry but I'm finding it's when trying to move them over the teeth of the core teeth that it gets very tight and the planetary gears do not spin as freely when they are pushed on.
At this point I'm wondering about cause or effect, were the old planetary gear set broken because of a defect in the teeth on the axle/motor core causing this resistance, or has that simply developed as general wear and tear? What are the tolerances for this, would you say from the video that the old motor core is unusable with those teeth? Or is there a way to fix them? It's obviously quite hard to sand or buff (other than with a steel brush) the teeth and it's only as the planetary set move about half way over them that it suddenly really starts to struggle.
Interested to hear your thoughts and hope the video outlines enough!