Thank you Steve, so it doesn't have a thread to unscrew, it just drops with heat, intriguing, looks like it needs to get very hot for the metal to expand?
I think its about a 1mm clearance, tight clutch wheels with minimal noise has a 1mm gap, and you aren't supposed to be able to see the bearings, if you can see it, it is too loose and it will be a screamer. I purchased a grubee engine, the clutch broke from first use..
and I have only had it a few weeks, third clutch now, & a tight engine. Lots of slip, not a tight grab. Lots of pedal pushing on clutch before it starts, but it is completely engaged.
I investigated it and found the shaft spring was damaged, the nuts holding the spring into place had jumped the thread and stuck jammed in. So engaging never happened until I replaced the shaft. Dodgy shaft
Grubee clutches use bigger woodroft keys and the keys were loose. I had to change the whole clutch with one that used smaller keys and a tighter fit. But I still have a slippy clutch. It 'slowly' engages when it should just grab and start.