Thanks Lowie, but the reason why it loosen itself up was because there were some glue in the outdrive that prevented the thrust bearing to rotate, so when i tried to rotate the diff then the screw instead rotated and got loose. But now it's fixed and it still very smooth and tight after few runs

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Tom3012: How hot does your motor get? Has the motor a sintered rotor? Mine gets really really hot even without the body

. But as I said before, a sintered rotor is on the way so I hope it'll fix the problem