How to keep pinion from falling off?
 

Hi guys,

I have a converted Hyper 8 running on 6s. It uses Mod1 gears and as a result, there is a fair amount of vibration between the pinion gear and the spur.

My problem is, the pinion keeps sliding down the shaft and falling off. At the moment i'm using removable thread lock to keep the grub screw in place. I'm worried that if I use non-removable thread lock, it will still slide off but I wont be able to get the grub screw out.

Any thoughts or experiences?


Cheers for any help!

do you have a flat spot ground on the motor shaft? this is essential - they won't budge after that. and, a good hex driver to really torque it down. i never use threadlock on my pinions - they all stay.

Yes it's placed on a CC 2200 motor which has a flat spot, and I screw it down as tight as possible without stripping out the screw.

I never had a problem with the pinion coming off my E-Revo, but that was Mod0.8 gears and didn't have to withstand nearly as much vibration as it is now, with Mod1.

I had a problem like this, I used blue loctite on the shaft and the grub screw.

"How to keep pinion from falling off?"

Duct tape and welds. Maybe use some glue too. And a screw. Plus you could put something very heavy on it. Like Uranus. That is heavy.

use a new set screw, loctite on both the shaft and screw...

if all else fails use a SLIGHT amount of red on the shaft...

Like ClodMaxx, I would ensure the motor shaft has a flat spot. Without a flat spot, you are relying on simply grub screw friction. But if it does slip, it will heat up the screw pretty quick and loosen whatever locktite you put on it.

I actually use a flat spot on the motor shaft and blue locktite just to be sure. From experience, it sucks to hunt around for the pinion if it does happen to fall off.

The brand of pinion makes a difference also...

Use the techniques above with RCM pinions & the problems magically go away

Thanks for the replies guys.

I'm using a HPI Savage Flux pinion, as all the other pinions had the wrong shape teeth (including the RCM one) which made a very loud grinding sound (see my other thread).

Anyway, I'm using blue locktite which I believe is the removable one. I never thought of putting locktite on the shaft itself, i might have to try that.

I don't really wanna weld it on, because then it would be very hard to get off!

one other thing that you probably know already, but it can't hurt to reiterate: if you're using loctite, make sure you give it at least 24 hours to cure/fully dry. anything less than that, and you risk it having the same holding properties of milk. :lol:

Yep, and it probably helps to clean most of the old stuff off.

Blue loctite on the shaft and grubscrew ftw- never had an issue myself using that technique ( allow to dry overnight is important too yeah ).

One other option is to drill or grind a little dimple onto the shaft in the right place ( on the flat spot ), then re-attach the pinion and tighten the grubscrew down into that dimple- that'll stop the pinion wondering along the shaft ( use blue threadloc too ofcourse ).

yeah i think i'll try drilling the flat spot, that should help.

Cheers

I also grind the tip of the setscrew to make it really flat. Flat on flat works wonders :lol::lol:.

i heard somewhere that you're not supposed to do that for some reason.:neutral:

It never failed me so far. I don't even have to use any loctite.

I always rough up the flat of the shaft with a grinding wheel on my Dremel and use Blue thread locker on the screw (dried) never had one come loose :mdr:

I'm shocked some have no issues and don't use locktite. I wouldn't stand a chance without locktite. But the locktite will loosen up if your pinion gets super hot. This can happen on mod1 grears if your mesh is out a bit. End of the day, two things that make the biggest difference for me is locktite on the screw and a bit on the shaft dried OVERNIGHT, and most importantly make sure your set screw isn't shiny stainless or smooth silver steel. It needs to be the black oxide finish. The smooth screws just don't grip in the threads.

i never had much of a problem with pinions falling off until today. i got my rc-m motor mount and pinion for my truggy and i managed 2 30 sec. runs. each time, the pinion fell off. also, the teeth are already looking kinda sharp where the pinion and spur made contact. the mesh was good and it is a rc-m pinion. i have had pinions wear away slowly and none that have issues with staying on the shaft.

the rc-m pinion i ordered is decaying very fast. only ~1 min. of runtime and already the teeth are sharp. the only other time this has happened to me is when i used a stainless, non-hardened pinion. it's like my brand new rc-m pinion isn't even the least bit hardened. maybe it's just a fluke?

IDk. I once got a 14T RCM pinion that lasted less than a day. Perhaps they didn't harden properly. Perhaps contact Mike or just bite the bullet on a new one.

I use green locktite onthe shaft and blue on the screws. Green is for shafts & bearings, and it does hold the pinion on very tight.

Yeah, I would definitely contact Mike. Sounds like the heat treatment wasn't done right for whatever reason.

well, i was able to get some runtime in today and the pinion stayed on after using blue loctite, but there were other problems...

http://i581.photobucket.com/albums/s...a/IMG_0003.jpg

the teeth wore even more and a tooth even broke off. i was running in fairly slick grass when it happened and the mesh was fine. i checked every other possible cause and everything was fine except for the gear. the motor mount and motor had no movement or play and everything else was fine. maybe the pinion gear was over-hardened. i sent mike a pm with the picture. hopefully, that will be enough to get a replacement without sending it in.

He should be cool with that- sometimes the pinions get overhardend or underhardened, so he's happy to replace them.

mike still hasn't replied to the pm or the e-mail i sent him. i included the picture of the pinion gear in the pm.

BrianG, can you ask mike if he got my message? my truggy is on hold until i get a new pinion gear and i would like to avoid getting another robinson racing gear. the one i run on my buggy wore out pretty fast and i had to get a plastic spur to stop the wear.

maybe i can switch to a plastic spur after i get a new pinion because it seems that every pinion i've ever owned has worn out when meshed with a steel gear. some last longer than others, but i don't have to worry at all with a plastic spur. the reduced gear noise is also nice:wink:
anyone know of a 45-48t plastic spur that will fit the crt x2 truggy?

Have you tried the Hotbodies pinions? I have a couple and they seem to be holding up quite well :yes:

i'll keep those in mind. they are nice and cheap. hopefully i won't need to get one if mike ever responds to the pm that i sent him...:whistle: