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Motor Stutter After Bad Crash

I nose dived my Dynam primo into the ground the other day. The elevator was not responding soon after take off and I couldn't pull up. Any way the crash caused the battery, servos and receiver to move forward with quite a bit of force. The battery was pretty distorted. So now the motor doesn't turn. It just slightly stutters. These electric motors seem pretty basic. They basically have windings and magnets and power. What actually breaks causing them not to perform?



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Faster than a speeding faceplant!
Look hard at the connections between the motor and the ESC. Broken solder joints or a broken lead will cause motor stuttering.

There are other places to look, but these are pretty common and a good place to start.
I checked the motor out and looked closely at the 3 wires that power it and one (the blue one) broke off. It was detached but held together with the others by heat shrink. Once I stripped the heat shrink away the wire literally fell off. There was may be 1/8" slightly exposes so I thought the motor was junk. Still I decided to try soldering the wire back on. It seems to have worked. First I put heat shrink on the other 2 wires as protection and then soldered the 3rd wire on. I then added heat shrink to this wire and then covered all 3 wires with a larger heat shrink to give the bond more strength. Connected the motor to an esc and batt and got her running. I now need to buy a fuselage and rebuild the plane. Hopefully all works out.


Active member
Such a severe impact can also bend the motor shaft. Just check that the prop runs true and nothing rubs. In many cases the motor shaft can be replaced.