TB Motor can loose from shaft

Ok, thanks! Will open it up later and see what’s inside! Also: are you sure the screw you sent in the picture should be there? It’s a very small screw-hole, I doubt you can get a screw of this type so small :smiley: I think a regular screw will do, as long as the head isn’t too big.

No it’s just big picture :sweat_smile: It’s the same screw which often used to fix the motor pulley. If the crew on the pulley is inside of the teeth you need one there.

On the motor shouldn’t be a screw with head. Have never seen as min

image Small picture but you should get the idea

I had this happen to the “Dark Matter” motors. Pretty sure Maytech makes the motors. Anyway the problem I saw when fixing it was that the shaft has a flat spot that the grub/set screw meets up with so the turning is locked in. Problem with that was the shaft was still able to move left and right becuase of the flat surface. When I opened up my motor, I saw lines of scratches from the set screw moving along the shaft,

My fix was dremeling a small dimple on the shaft where the set screw meets with it. Then I swapped in the POINTED screw pictured above instead of the flat one It came with.


My latest dark matter did the same… the shaft had a dimple on one side and a flat on the other, but one of the grub screws was loose. I just loctited them back in. Done about 100k since then, all good.

Sadly, it seems like this is a common problem with TB motors. I have had two of them now and both did the same thing as yours. Here is the solution that is currently working for me:

  1. Remove set screws completely. Pour in a few drops of green Loctite 680 into the open holes. Then spin the can around the shaft a few times and let it dry. A few hours is probably enough time. I’d like it dry overnight. This will allow the can to be glued to the shaft.

  2. Then put in new set screws with red Loctite. I upgraded my M4 set screws to ones with a larger hex pattern, so that I could torque it down harder. Let the red Loctite cure for another 24 hours.

Then you should be good to go. Here are some pictures:



Update: turns out there actually were grub/set screws still in place :smiley: I just had to use a flashlight to spot them. Tightening them did the trick; but will still be taking it apart to investigate the noise.

vibration is what loosens them over time, so the issue will return eventually. check them constantly

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Of course! Bought myself 2 types of threadlocker: one that permits unscrewing the part later, and one that cannot be undone :smiley: Bought the latter just in case, but am now testing the non-permanent one, and nothing has unscrewed yet. :slight_smile:

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Update: took the motor can off (not sure why removing the circlip was necessary, as the shaft wen out one way, and the can the other way) and figured out what was making the slight scratching noise ( I think) – the sensor wires’ protective tube/sleeve wasn’t cut short enough, so its end must have been touching the can in some places, but not others (not sure why, as the can is symetric :man_shrugging: ). After doing that, the sound is gone, and the motor is good as new! (Well, except for, you know, the dead hall sensor :laughing:)

Went out for a ride yesterday with my half-assembled board, and the motor can got loose from the shaft again. This time, however, it isn’t the grub/set screws getting loose that’s at fault – the can is swiveling perpendicularly to the screws! :open_mouth: I shot a video to explain the problem better:

The can ends up scratching against the non-spinning part of the motor, so creates a lot of resistance, and of course, noise when riding. Because I’m using standard caliber II trucks with 12mm belts, I’d need a motor of the same (or smaller) width, which I think leaves me with TB as my only option, but since this seems to be a common issue with their motors (and pebbles fly into them sometimes because they aren’t sealed), I don’t want to do that :grimacing:

(Edit: TB isn’t my only option; Flipsky sell motors the exact same size. As of writing, they still have issues with loose magnets though, so no thanks :stuck_out_tongue: )

How hard would it be to drill through the motor can and the axle perpendicularly to the existing holes to just put a shaft through it? Any other ideas?

Opening snap rings is the definition of “hard” if you don’t have a circlip tool.


Can confirm, took 30 minutes of trying different things to get mine off.

Pick tools work the best lol

And use ccorrectly so they don’t brake :wink:

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There are literally like 3 pieces to brushless motor. Take motor off the mount and see what is missing/loose. My bet is the circlip is gone.

Circlip isn’t gone, and even if it were, that wouldn’t impact the can moving relative to the shaft/axle anyway.

Taking the motor off the mount helped anyway – turns out the axle had rotated, so the swiveling was probably because of the axle not being round at that angle. I guess I must have tightened the grub screws with the axle in the wrong place somehow, or it moved when riding. Either way, I’ll replace the grub screws again and hope that the issue is gone :crossed_fingers:

Edit: Nevermind, after taking the motor apart, I now see that the flat spots on the axle don’t match up on one end and the other. Looks like I had secured the grub screws properly in place after all. :frowning:

Never had this issue myself with TB motors, but to your comment that buying a new motor would just be replacing the same thing, there has been some slight design changes in the TB motors, even in the last year. My older TB motors have had more issues than the current ones I’ve bought, I think he’s cleaned them up a bit from older versions.

Naw. Wrong tool for the job.


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