I've been fighting with Solink's helical bevel/pinions for a while now and I just cannot get them to mesh like you hear on their promotional videos. I've tried four sets now, three from gears and one stand-alone like this product, and *none of them* is anywhere near as quiet as advertised.
I even took the time to test my shimming .05mm at a time, alternating between .1 and .15mm shims. Motor was aligned, tower fit snug in the gearbox, bevel to pinion shimming, low profile bushings, molybdenum grease brushed onto the axles and tooth meshing faces, and slightly adjusting motor height back and forth at each step.
By all accounts I should have found the sweet spot for where these needed to be shimmed for quiet meshing, but no matter what I tried, they were - at best - barely quieter than my normal ZCI, SHS, or Jvan bevels.
Worse yet, when I did finally get somewhat desirable sound out of them, I had to shim the bevel so high that it threw the spur and sector out of alignment of the piston and tappet plates, making it impossible to finish the build.
This is just simply a badly designed gear.
If you really want a spiral bevel/pinion, just go get Lonex's set. I got one to test and nearly bullseye'd it my first try. Made one adjustment and now it's flawless. No meshing noise in an empty shell, and on my 19k brushed motor running -4 tooth 12:1's, it nearly matches the sound profile of my 25k Brushless build using similar ratio and short stroked JVan gears.