Aroma Fireteam pinion keeps coming off? Any suggestions?

[jojobeans]

Friend of mines Fireteam keeps ejecting pinion gears. It's winter, so we're not really running them that hard and its the only car having the problem. We've tried every strength of lock tight you can buy, different pinion gears, different grub screws, etc. We've tried letting it cure for multiple days at a time as well. As soon as you run it, about half a pack in, the pinion comes flying off the car. In all my years of experience I've never been this defeated over a pinion gear.

9/10 the grub screw remains on the pinion, although there's been a few times its been gone as well. We always make sure its cleaned with alcohol and a wire brush and well screw the grub screw in with it off the car to make sure that its actually able to make contact with the shaft. Motor shaft looks good and flat, the pinions are keyed so they only go on one way and its practically impossible not to screw the pinion down to that flat spot.

What are we doing wrong? Any tips?

 

[coldvod]

clean it then apply threadlocker only on the first few threads though. i use red on my 6s pinion but people say to only use blue on rc cars https://www.henkel-adhesives.com/ca/en/products/industrial-adhesives/threadlockers.html

 

[Jerold]

I will second and third what @coldvod said and add to that

• Let it cure for 24 hrs at room temp.
• Just drop will work. Too much is a bad thing.
• Use heat and good tools every time you need to break it loose.

I use blue thread lock (not as strong) but I also check it regularly and do shorter speed runs. Red or blue - your call.

Red or blue I can't stress enough to use heat. Cook it well you won't hurt it. If you start flexing your driver, heat it some more. Be careful of your plastics.

This is what I use, you can generics one from Amazon and Harbor Freight.

 

[nino]

Is something out of whack? Like, maybe the mount is at a slight angle or something got bent or something's not tight enough... I'm thinking that something is causing the pinion to walk. Like, it not being parallel to the spur. Is the motor ok, shaft straight and centered?

Because it's obviously not the pinions' or threadlocks fault if you keep losing each and every one...

 

[WickedFog]

+1 nino. That would be exactly the things I would be looking at. Check the gear mesh all the way around the spur. If it gets tight, then loose, check the motor shaft for a bend. It may be impossible to spot with the naked eye, so putting an indicator on the shaft might be needed.

When all else fails - tear the car apart and rebuild. You may not even find the problem, but reassembling may fix something you didn't see, or you may find a problem hidden in an assembly that is causing it. Pics might help someone here spot the problem as well. Sometimes it just takes another pair of eyeballs

 

[Jerold]

+1 nino. That would be exactly the things I would be looking at. Check the gear mesh all the way around the spur. If it gets tight, then loose, check the motor shaft for a bend. It may be impossible to spot with the naked eye, so putting an indicator on the shaft might be needed.

When all else fails - tear the car apart and rebuild. You may not even find the problem, but reassembling may fix something you didn't see, or you may find a problem hidden in an assembly that is causing it. Pics might help someone here spot the problem as well. Sometimes it just takes another pair of eyeballs

Could be bent or out of whack. Always check your gear mesh, it should have a bit of play between the gears. If you stuff them in there it's not only a lot of friction but a heavy load on your motor and can cause damage over time. Definitely check it but for bent or damaged parts. Everything they said.

At the same time Arrma is notorious for skipping thread lock on grub screws (pinion, drive cups and spools). I mean the pinion is only turning at 51,000 RPM, what could go wrong?

If you take out screws coated with white powder (dried thread lock) clean them up.

Get your mini torch and heat it till is smokes then wire brush it. I suggest you use a set of locking pliers (Vise Grips) to hold the screw by the head while you do this. Let it air cool, don't dunk it.