A Good Tool for Grub Screws

[Kowalski86]

I've been having a new problem, everytime that my M05 goes out for a drive the pinion gear comes loose.

I've tried the cheap L tool, a proper tip on my usual screwdriver tool, and even a tiny bit of loctite with no luck.

Is there some sort of "better" super cool tool out there that I'm not aware of? Or is this simply the effects of a small car with small shocks being bounced around by my street?

[Aerobert]

I think the tool is secondary. Use a little bit more than a tiny bit of Loctite 243. 

[Kowalski86]

Just now, Aerobert said:

I think the tool is secondary. Use a little bit more than a tiny bit of Loctite 243. 

I'm wondering if it just isn't the combination of my street and my car not getting along. None of my buggies have this issue.

[Aerobert]

I don't know, could be possible.  But it could also be possible that due to manufacturing tolerances or wear the grub scew didn't match perfectly with the pinion. Maybe try another grub screw and/or pinion and don't be to shy with the Loctite. 

[Sogogi]

When i use those tamiya tool set hex driver(blue handles), i cannot put enough torque to tight down grubs. I always finish it off with kit included hex wrench (use longer side as a handle) to tighten it up bit more. Never had issues so far

[Kowalski86]

10 minutes ago, Aerobert said:

I don't know, could be possible.  But it could also be possible that due to manufacturing tolerances or wear the grub scew didn't match perfectly with the pinion. Maybe try another grub screw and/or pinion and don't be to shy with the Loctite. 

I think Ill give that a shot along with Sogois suggestion. I might still have a few spare grub screws.

[Twinfan]

1 hour ago, Sogogi said:

When i use those tamiya tool set hex driver(blue handles), i cannot put enough torque to tight down grubs. I always finish it off with kit included hex wrench (use longer side as a handle) to tighten it up bit more. Never had issues so far

I do this, and use Loctite Purple (222).  No issues whatsoever  

If you need to remove the pinion, and it's a bit stiff, a bit of heat is all you need e.g. a hairdryer.

[toyolien]

Definitely thread lock. That'll sort you out!

[alvinlwh]

Grab screw do get worn out, but check your type first.

This is the worst for pinion coming off.

And these are better.

But the best I had found combined both the point and ring of the above but I cannot find a picture of it.

As I said, grab screws get worn out, check if your point and/or ring still is sharp enough to to bite onto the shaft. Threadlock will not help with a worn out grab screw.

EDIT:

Without opening my drawing app, the section profile of the grab screw above.

\_____/

\/-----\/

-\/-

\/-\/-\/

Hope you get the idea.

I think that Surpass and 3R supply the best grab screws with their pinions. Never had a problem with pinions coming off with them.

FURTHER EDIT:

Found a picture of my worn pinion. Not a good picture, but zoom right in and you can see the "ring" is more flat \_/--\_/ than sharp.

 

[Kowalski86]

3 hours ago, Aerobert said:

I don't know, could be possible.  But it could also be possible that due to manufacturing tolerances or wear the grub scew didn't match perfectly with the pinion. Maybe try another grub screw and/or pinion and don't be to shy with the Loctite. 

I'm beginning to question the tolerances part, its a Robinson Racing pinion and in the past I managed to strip out one of their grubs by accident.

[OnTheTrail]

Another thing to try is to heat the pinion before you put the Loctite'd grub screw in.  Get your soldering tip in there for a while and try to heat the pinion in the area the screw will be inserted.   If you can do this off the motor shaft the better but I doubt that much heat could transfer to hurt the motor.   Then put the screw in allow it to completely cool and let the Loctite set up.  

[Nicadraus]

I never used loctite or any kind of glue/adhesive screw lock to hold my screws.

I use MIP tools. They're one of the best if not the best. Tips don't wear out like others does. Holds, hex screws very well and they're magnetic. 

That should solve your problem.

https://www.miponline.com/MIP-Hex-Driver-Wrench-Set-Metric-3-1-5mm-2-0mm-and-2-5mm-9502

[one_hit]

Like mentioned above, you need to invest in a proper RC steel hex driver, not those cheap L-shaped allen keys or universal screwdrivers with removable tips. They are long, thin but strong, and able to reach places those cheap tools can’t, such as the grub screws for adjusting droop on touring cars. Even the hex drivers that come with the Tamiya RC tool set (blue handles) are no good, I only use the JIS screwdrivers and nut drivers in that set. I’ve never had to use loctite on the pinion grub screws of any of my Tamiyas, only on my larger 1/8 and 1/5 scale cars.

[Juls1]

Have you damaged the motor shaft where the grub screw is trying to grip? Sometimes you can accidentally tighten not perfectly on the flat which causes it to come loose at a indeterminant time. But then the shaft can be damaged as well causing it over and over. 
 

As others have said, MIP tools are a must for anyone serious about not damaging hex heads and being able to tighten adequately every time.  I’m not sure there is better tools than these available. 
 

loctite isn’t normally needed on pinions, but if the gear material and grub screws are of similar hardness sometimes they won’t bind very well in which case loctite may be needed. 
 

 

[TheMidnight Pumpkin]

On Amazon they sell dedicated RC car tool kits for $100 USD or less. I bought the fancy gold colored ones and have not had any problems since.
They have a weird name - globact rc tool kit

They come in zippered enclosures and are super convenient to bring to the track. I’ve got nothing bad to say about them.