so i binned my 5inch pretty hard into a concrete barrier at the track last weekend, arm looked okay visually but one of the motors started making this weird grinding/rattling noise when i spin it by hand. it's not super loud but you can definitely feel something off when you roll the bell. prop was toast obviously but i replaced that and the noise is still there.

the thing is im not totally sure if the grinding is from the motor itself or if maybe something got into the stator housing. i pulled the bell off and didnt see anything obvious, no bent shaft that i can tell, magnets look fine. ran it on the bench without props and it sounds okay at low throttle but gets rougher as you spin it up. temps seem normal-ish after a short hover but i havent pushed it hard since the crash.

do i just replace the motor at this point or is there something else i should be checking first? these are T-Motor F40 Pro IVs and i'd rather not swap if i dont have to but also dont want to cook an esc if something lets go mid flight

if you can feel it grinding when you spin the bell by hand that's pretty much the bearings. concrete impacts are brutal on them even if the shaft looks straight. i've had motors that looked totally fine externally but the bearing races were cracked inside. not worth the risk honestly, especially on a motor thats spinning at 30k+ rpm. T-Motor does sell replacement bearings separately if you want to go that route and save a few bucks, theyre usually standard 9x4x4 or similar depending on which variant you have, easy enough to press out with the right tools. but if youre flying at a track id just swap the whole motor and move on, your time is probably worth more than the bearing cost difference.

yeah same thing happend to me with an xing motor after a gate hit, spun fine slow but got real rough up high. ended up being a slightly bent shaft that i couldnt see with the naked eye. i tried to true it up with a shaft straightening tool thing i saw on youtube and it kind of worked but not really lol. just replaced it. not worth the headache