Do I Have a Bad Motor? - RC Groups
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Oct 04, 2012, 06:05 PM
You Enjoy Myself

Do I Have a Bad Motor?

DJI F450, NAZA/GPS, stock motors and ESCs.

I had a crash last week, broke an arm off my quad after it came crashing down when I brought it too close to a tree and it clipped some leaves.

I just replaced the arm. Didn't do anything else and reattached everything.

I made sure I put the motor connector wires into the ESC on the arm that I replaced as it was before. But I did not test to see if it was spinning in the right direction.

When I went to fly, the quad would just flip over.

I brought the quad home and unhooked all the ESCs, plugged them back in, then tested and fixed until I got all motors spinning the right way.

Motor 1 seems to be giving me problems. It was arm 4 that broke though. Maybe motor 1 was damaged in the crash too?

As motor 1 spins, it seems normal. When I move elevator up, or aileron right, motor 1 spins fast, then slow, then fast, then slow, and repeats. It seems normal with elevator down and aileron left.

Motor Spinning Test - DJI F450 (0 min 24 sec)

It's probably an easy fix. At least I hope it is.

Should I have recalibrated or done something in naza assistant after reattaching the arm? I haven't done any calibrations or any change settings in naza assistant after I got my quad back from Tony about a week ago.
Last edited by cwg25; Oct 04, 2012 at 08:52 PM.
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Oct 04, 2012, 07:25 PM
Registered User
Well, I didn't quite understand what you are asking. I couldn't watch the video you posted. It says it is private and needs a log-in.

Changing an arm or a motor or both doesn't require any calibration but it also wouldn't hurt anything if you recalibrate.

Damaging a motor during a crash is not uncommon. It is generally the bearings that get damaged.
Oct 04, 2012, 09:00 PM
You Enjoy Myself
Sorry, had the video set on private. The bad motor is the one in the upper right.

I'm just curious if somebody can tell if it's definitely a bad motor.

On second thought, that's not such a good video. I rushed to get it up. I'll just replace the motor.
Last edited by cwg25; Oct 04, 2012 at 09:05 PM.
Oct 05, 2012, 03:29 AM
Registered User
Just watched the video. I hear a strange noise (not sure if it is coming from that motor) and also I see some vibration on that motor. I watched it twice.
You might have bent the shaft or maybe damaged the bearing.
Take the motor out and spin it while holding it and see if there is any excess vibration comparing to the other motors...
Oct 05, 2012, 10:08 AM
You Enjoy Myself
When I manually turned the bad motor, it was more sluggish than the others.

I replaced the motor, didn't hear the same type of noise as before. I made sure all the props were turning in the right direction.

But now when I throttle up, my quad stays on the ground.

Oct 08, 2012, 09:01 AM
You Enjoy Myself
I had the wrong prop types on the motors. I fixed that and my quad was able to take off.

But now it is spinning out of control. Is this still a bad motor issue?

All I am doing here is throttling up, then down. I'm in GPS mode, single green blinking light before takeoff.

DJI F450 Out Of Control (0 min 8 sec)

Arm #4 broke, I replaced that and motor #1 because it sounded/acted bad.

Will replacing motor #4 fix an issue like this? Calibrating the GPS? Anything else?

I had trouble searching for an answer. Maybe somebody can see an easy fix to this problem by watching the video?

Though I could have tried a couple things, I didn't want to in case I made it worse.
Last edited by cwg25; Oct 08, 2012 at 09:31 AM.
Oct 08, 2012, 02:11 PM
You Enjoy Myself
Does the video in the previous post look like a motor or ESC issue to anybody?
Oct 08, 2012, 03:25 PM
lovegroove's Avatar
Hmm? Something is definitely not right there. I think you need to go back to basics with the tuning and work your way up. Forget altitude hold and GPS hold for the time being and just get the basic flight characteristics tuned first, because the GPS and altimeter could be adding to your woes.

Are you sure that your motors are spinning in the correct direction? quadcopters use change of motor torque to control yaw, so if you haven't got the motors going in the right direction then when the controller detects yaw the problem will get worse and worse as it tries to correct but can't because the motors aren't spinning in the correct direction.

I wouldn't normally recommend it, but if you get a good hold of the copter and hold it above your head and slowly apply power you should feel resistance when you try to pitch it forwards, backwards, left or right or if you try to spin it. If you don't feel this then go back through all of your settings again.
Oct 08, 2012, 05:17 PM
You Enjoy Myself
Well, well. Look like the noob made a noob move.

Long story short, after fiddling with motor rotations and proper prop placement, I finally got it all right and the quad flew. It was windy out, but it held up pretty well. I'm glad it was my fault rather than faulty components.
Oct 08, 2012, 05:34 PM
lovegroove's Avatar
Sweet, glad you got it flying! Where's the video?
Oct 08, 2012, 08:06 PM
You Enjoy Myself
Not so much wind here, pretty steady.

Back To Life - DJI F450 NAZA GPS (0 min 16 sec)
Jan 05, 2013, 01:13 PM
Registered User


wha did you do to fix this as i am having same problem help plz

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