Better energy transfer, less wear, smoother and quieter. 
transfers the load forces on the gearshaft away from perpendicular.
If you’ve ever driven a Lada Niva with square cut gears you’d understand why helical gearing is so much better. 
Try an International Scout. Straight cut gears! Was a running joke with a friend of mine that’s sadly passed away these days. We had some fun that’s for sure.
Lada Niva, those rust buckets don’t even go do they
Look forward to a review
Not anymore.
My mate bought one in the 90s… absolute Russian POS.
Weirdly though, they won best compact 4x4 in 2021. 
I know but then you can’t get parts for them. Plasiba
The grub screw holding the pinion gear in place went AWOL today. Judging by the Vernier’s its an M2 grub screw about 5mm long.
What’s the consensus on the best Loctite to use? I’ve got purple but it has failed me a couple of times. Wondering if blue is the way to go.
I use blue, and let it cure overnight ideally.
I’d even go for red 262 loctite, higher strength and temp before melt. Being a small grub screw you can’t get much on it.
That area will get a bit warm and melt lower grade loctites me thinks.
Superglue is another alternative. Temp irrelevant, won’t take much load so is easy to undo as it cracks.
Warhead recommend Loctite 638, but it is hard to find in Australia and not cheap.
On brushless I use red, but on anything I give a good with isopropyl alcohol, as nearly every pinion and motor shaft has a coating of some oil/lube to keep it from oxidising before use.
I have been using a ton of t238 brushless motors, especially their blue “value” line and they come with the pinion already set it just saves me one job and an overnight cure!
Their “premium” grey ones do not come loctited, which is handy for builds where the pinion needs to be set a little off the end of the shaft, they also come with a bit nicer pinion or you can use one of your choosing which is handy. Otherwise the only benefit is a trim pot to reduce the speed but I have never used it… nobody wants their build slower!
If anybody wants free shipping on their website for motors and ETUs, the code GBNOBODY gets it. The good people at T238 were kind enough to provide me with that. I buy enough stuff from them and they look after me well. 
Otherwise just order over $98USD and use the code offered for email subscribers for 8% off.
Best to get 638 online, that would be a good one for the purpose
50ML LOCTITE 277 243 262 261 648 638 271 272 290 263 277 Screw Nut Retainer AU | eBay
Great info thanks guys, very educational
As an afterthought, is there any merit in cleaning the parts with acetone, then roughing up the mating surfaces with some sandpaper to give the Loctite some extra tooth to hold onto?
Realise these parts are small so you’d really onto get some sand paper onto the motor shaft
No need for roughing up the surfaces, as Loctite works in the thread gaps to bond the screws/bolts, but definitely require a thorough cleaning with acetone/alcohol and use the primer for extra bonding strength. 
Can use a ciggy lighter or heat torch to loosen the bond if needed to be removed in the future.
Sorry it wasn’t so much the thread I was referring to, I’d never go to town on that with sand paper.
More so referring to the flat surfaces on the motor shaft that will make contact with the inside of the pinion gear. Probably not worth the effort given how little surface area there is to work with.
If the pinion is not snug or tight on the shaft getting Loctite on the shaft inside the pinion will only help… just have to be careful to not get it in the bearing on the shaft tower!
The pinion that comes with warhead motors was quite loose on the shaft, I always made sure the Loctite got good coverage inside them as I have had a few work loose even with the grub screw loctited and torqued down heaps.
There is a lot of rotational force and vibration on a small surface.