I thought retaining compound was the shit for motor shaft <-> motor pulley interface, but in this thread there are at least 2 members with multiple failures. I’m shook. Let’s collect some data.
It works – don’t need key or grub screw
It failed me once – not sure if I trust it
It failed me but it was user error
It failed me multiple times – it’s crap
0voters
Especially if it failed, can you post some details? drive train specifics (belt? gear? chain? gear ratio?), type of pulley (alu or steel), type of retaining compound, did you clean, did you let it cure, etc.
For me, I use 648 (high temp). Steel pulley, kind of a loose fit. No key no grub screw. I had 1 failure, after maybe 1.5 years of almost daily commute. Cleaned the hell out of it, put it back with 648, and it’s all good.
For further info, this pdf is kind of intense. page 16-17 have charts.
I thought 648 was high strength high temp, but maybe I should be using 638. The difference seems to be viscosity/gap-fill (648 thin 638 thick) and a bit more strength for 638. Temp range is the same.
I think there’s a topic on the old forum about this and it explained that there was too much space in between the pulley and the motor shaft that the threadlocker never properly sets and you’d be better off just threadlocking the grub screws. May be wrong here 50/50.
It’s worked fine for me, @eBoosted is a big proponent as well. But to be honest I just feel safer with a key and grub. It’s like it works fine but I don’t trust it yaknow?
I used green loctite on my motor gears (not pulleys), no grub screw.
On a group ride, I hit a nasty piece of asphalt directly to my gear case. Immediately went to 1wd. I figured the loctite gave and the motor was free spinning.
Nope. It held and my 4 motor screws actually loosened enough for the whole motor to slide out of the way even when a bolt backed into the mesh.
It failed on me several times, but because I rode it after only 20 minutes of curing time, I’ve been runing mine for almost 3 months without any issues at all, I’d say it’s 5 times more reliable than a regular grub screw tighten excessively
If it’s possible I would always use keyway or flat spot and set screw plus loctite.
With this said, I think only loctite can work well too depending on the application.
If you run belt without idlers for example your belt will rather slip than rip of the pinion.
I run my gear drives with loctite only and had the motor gear come lose twice.
I cleaned the motor shaft properly and was waiting usually even more than 1 day before I took it out for a ride.
Things I changed to get it better fixed.
Sanded the shaft a little bit.
Using loctite 638 and some local red fake loctite which is very strong and not as much fluent like the 638. why? Because I think the gap between shaft and motor gear was too big in that one case.
It also seems to make a difference if traction control is switched on or not. With traction control there seem to be less stress on the motor gears if that makes sense.
So in short, yes it can work, but I would always prefer to have a „hard lock“ as well.
Unfortunately it’s not always possible if you use 10 or 12mm motor shafts.
Used the same before, my pulley was also very stuck, just get a big blowtorch it will take care of it in a few seconds. I used a smaller torch at first which didnt work.
