Pinion gear and spur gear keeps coming loose

[BriaN]

I would casually drive my ECX amp around and it would randomly make a loud whirring sound. I would check the spur gear, and whenever I check, I see that the spur gear and pinion aren’t even touching each other one bit. So I loosen the pinion, then reset the gear mesh, and screw them both back in. But this keeps on happening over and over, no matter how tight I tighten the screws. Would it matter what pinion I used? Any help would gladly be appreciated.

 

[BriaN]

Oh and I apologize if my “terms” for things are wrong

 

[X]

Have you been using blue loctite on the screws holding the motor? Perhaps they are backing out.

 

[KyleRC]

Loctite and tighten them down a little bit more. Also make sure the pinion gear’s grub screw is on the flat part of the motor shaft or it will come off for sure.

 

[BriaN]

Have you been using blue loctite on the screws holding the motor? Perhaps they are backing out.

I used loctite on the screw that is in the pinion gear. Which screws would I put the loctite on? The two screws for the pinion, right?

 

[RazorRC]

The pinion gear is the small, roughly 15 tooth metal gear on the motor shaft. It has a tiny black grab screw that you need a 1.5mm hex driver to tighten. The grub screw should be tightened on the flat part of the 1/8" motor shaft.

The spur gear is the large, black plastic gear with around 70 teeth (no idea the actual count, probably somewhere between 60 and 80 teeth). It has a large metal plate on each side of it and a large spring pushing the plate against the spur.

What is coming loose, the metal pinion gear is sliding up and down the motor shaft? Or is it the actual motor that is held on by two 3mm screws into the plastic transmission case that is coming loose?

 

[X]

I used loctite on the screw that is in the pinion gear. Which screws would I put the loctite on? The two screws for the pinion, right?

If it is the pinion moving away from the the spur (not the pinion sliding on the motor shaft) then yes. The two screws that hold the motor in place also adjust your pinion/ spur mesh I believe. Been a while since I've looked at a 2wd ECX, but that's usually how it works.

 

[BriaN]

If it is the pinion moving away from the the spur (not the pinion sliding on the motor shaft) then yes. The two screws that hold the motor in place also adjust your pinion/ spur mesh I believe. Been a while since I've looked at a 2wd ECX, but that's usually how it works.

To reply to both of you, I think that it is the pinion moving away from the spur. The grub screw is in the flat side, and it does not move up and down the motor shaft.

The two screws on the left are the ones I have to keep tightening. The pinion always moves away (shown in second photo)

 

[BriaN]

When I loosen those two screws, the motor does move around, so yes those are for the motor as well. I don’t know if this is connected, but the motor shaft on the motor is supposed to go up and down, right. I can actually press the motor shaft up and down(if I was holding the motor vertically) (this is a brushless motor)

 

[WithinU]

If the screws that mount the motor are not loosening, there is possibly something wrong with the motor itself.
If the motor mounting screws are loosening when running, then double check the screws aren't too long for the motor. (bottoming out before tightening all the way)
And maybe put a dab of locktite on them. Although I hate to tell you that.

 

[BriaN]

But

If the screws that mount the motor are not loosening, there is possibly something wrong with the motor itself.
If the motor mounting screws are loosening when running, then double check the screws aren't too long for the motor. (bottoming out before tightening all the way)
And maybe put a dab of locktite on them. Although I hate to tell you that.

But I was thinking, if I put loctite on them, wouldn’t that hold the motor in semi permanently? Also, how would I check if the screws were too long? That might be the reason because the pinion just,keeps moving away from the spur. I didn’t check if the screws loosened while this was happening though.

 

[RazorRC]

A little blue loctite and crank em down. Should be good. Blue loctite is pretty mild. You can easily unscrew them whenever you want. Don’t use the red stuff!

 

[BriaN]

A little blue loctite and crank em down. Should be good. Blue loctite is pretty mild. You can easily unscrew them whenever you want. Don’t use the red stuff!

Okay thanks! I’ll try it and see how it goes .thanks to everyone

 

[zderekv]

Also make sure each of those 2 motor screws have a lock washer between the head of the screw and the plate that’s sandwiched between the motor and those screws. This will both help keep tension on the screw and take away some of the length if the screw is bottoming out.

 

[BriaN]

Also make sure each of those 2 motor screws have a lock washer between the head of the screw and the plate that’s sandwiched between the motor and those screws. This will both help keep tension on the screw and take away some of the length if the screw is bottoming out.

Yup ok! Thanks

 

[DemonTime]

Yup ok! Thanks

Question, I am having semi similar problem as you are, That is my Pinion gear keeps coming off of the 3.75m Shaft and I tighten down the 1.55m Hex, it just comes off and high speeds? How do I fix this do I need to glue it ? Or what. Thanks