TB Motor can loose from shaft

https://www.youtube.com/watch?v=RU_QWrjOC7Y Video explains it best – the shaft has some wiggle room relative to the can of the motor. Didn’t notice this when I first got them (been riding for just 2 days). The noise also troubles me a bit, as the 2nd motor I have doesn’t do that. I’m guessing that the noise might be from a burnt component or something (They’re sensored 6355 TB motors, and I accidentally burned the sensor on one because I connected the sensor wire to the wrong place on my vesc :man_facepalming:).

People on the forums with similar problems were told to tighten the grub screws of the motor, but I’m not sure if the grub screws are inside the can, or if they’re supposed to be here: IMG_20180913_231819_2 If so, then they’re missing from both of my motors, but my 2nd motor is perfectly fine, so idk. :man_shrugging:

If these so called grub screws are inside, then what’s the best way to open up my motor? It took me half an hour just to get the pulleys on the shaft, because of how tight they sit, so I’m afraid taking the motor apart might be even harder :grimacing: What should I do? (I’d order a new motor if I were in the US, but shipping to europe + UK taxes ain’t worth it)

First…damn there should be screws fixing your shaft!!! They usually inside, so take a second look. Allen key should fit for it.

Secondly, it’s not hard to take away the motor can. Just open the snap ring on the side where the shaft is. After you can already pull away the can. Might be you need a bit strength as the magnets hold the can. But it shouldn’t be a big problem

Question is: would inserting these missing screws be enough, or do I also need to open the motor up? I’m not sure if the motors came with those screws missing, or if they fell out while I was riding…

I don’t know the English word for it :sweat_smile: but this screws should be fixing you shaft image

Please double check it. If they really missing than first step would be to replace them. Glue them inside with loctite too.

If you hear strange noises out of the motor better to open. It’s really not difficult. It always can be that magnets came lose or other shit is inside

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.