so i binned my 5inch pretty hard last weekend, caught a gate post clipping through a gap and the quad just went straight into the ground at maybe 60-70kph. frame is cracked but repairable, two props shredded, and one motor is definitely toast ? it just grinds when i spin it by hand and there's visible scoring on the stator. the other three seem okay but honestly who knows.

the thing is this was already kind of a franken-build, been flying it for almost two years, mix of leftover parts from other crashes. the frame is a stretched x i dont even think they make anymore. motors are 2306 2450kv whatever was cheap when i built it. total replacement cost for just the one motor is like 15 bucks but then i start thinking ? should i just swap all four for consistency? or is mixing hours on motors actually not that big a deal as long as they test fine on the bench?

also wondering if its worth checking the ESCs more carefully, the one on the dead motor arm got pretty hot after the crash which might just be from the motor fighting itself before i cut throttle but im not sure. anyone done a full post-crash teardown and found hidden ESC damage that wasnt obvious at first?

honestly if one motor is visibly scored inside you should at least check the other three before assuming theyre fine. ive had motors that felt smooth on the bench and then threw a phase about four packs later because the windings got heat stressed in the crash. not always obvious until it fails mid-flight.

on the ESC question ? yeah definitely worth pulling it and looking for burnt smell or any discoloration on the FETs. if the motor was grinding after impact the ESC was basically dumping current into a partial short and those little FETs dont always show obvious physical damage even when theyre marginal. i had a 4in1 that passed motor spin tests for a week before it just let go over concrete. if youre already this deep in the teardown just pull the stack and give it a proper look.

as for mixing hours on motors, i do it all the time on practice quads and havent had issues but on anything you care about id probably just match them. 15 bucks a motor isnt nothing but its not much either if youre rebuilding anyway.

the ESC thing is real, had exactly this happen last spring. motor seized on impact, ESC looked totally fine, flew it once more and it just cut out mid-punch. couldnt even tell visually, had to actually probe the FETs to find the dead one. now i replace the ESC any time a motor goes through a hard stop crash, just not worth the risk tbh