Knocking sound on some motors when bending propellers


Have 6 Tiger Motors (MN4014) on a hexacopter.
This is when they are off.
When lifting one propeller tip, the motor gives a little knock-sound, on some motors.
Motors have been used over 20h.
Is it the bearings?
Is it normal? Is there a little play?
Something to worry about?
I know Tiger Motors should have their bearings changed after how many hours it was… 50-60?
How do I know a bearing is getting bad?
Hot motor? Any special sound when using them?


What you are testing is bearing wear.
It happens with all but the most specialised bearings.
Is it excessive?
Depends on the amount of movement.
If you ‘just’ feel it, that is usual, and found in all motors, to varying degrees, after hours of use.
If the bell of the motor starts to have a visible ‘rocking’ motion then it is probably time to replace the bearing with good quality ones.
20 hours isn’t that much use.
Have the props struck anything in use?
Has it been transported roughly?
Have you been near the sea or salt water?
These things can affect bearings.

Its only on 3 motors. Louder clicks on two of them.

We dont see the movement, just hear this distinct click that sounds a lot more through the frame standing by it self, than when holding the boom with one hand. Maybe I should YouTube it some day. I have had movement in motors, but no clicking sounds. Some props have got in the lawn when we had the tilting problem in the beginning, but that wasnt much rpms and they didnt stop like buried into the ground, only dirt on the tip. The arm rested on the lawn.

No transportation problems as we know.

The motors were used when we got them, so we dont know much of its previous life. The rig with the motors werent crashed.

Not so salty water around here, but we do live on an island. But thats not any problem.

By the way, this rig is doing its job very good, flying now and then (even in the cold), very satisfied (building a similar X8 now, all new parts including the motors).

But as you say, nothing to worry about now.
New bearings when needed.