Quadcopter Motors Shaking Front Left and Back Right


I am flying APM 2.5 AC v3.1.2. Recently, my front left and back right motors started shaking with increased throttle during flight. This error was not present in the past so I think that my PID values and vibration levels are OK. Motors and props are pretty well stabilized too. Any idea why this could happen?

That same thing happens to me if I try and take off from grass or any surface that isn’t concrete… I things it’s how the copter is responding to the air that bounces back to the props from the ground. On concrete it may slide along the surface and out of the way where as grass blocks the air from completely flowing away so it bounces back to the prop… I’ve also learned on grass to take off real quick to avoid it…

Do you have a log file from your flight. specifically .bin. If motors are shaking it will be easy to see in the vibration portion of the in flight log file. A few questions / troubleshooting tips

Have you balanced your props?
What type of props are you using?
What type of motors are you using?
Has this problem always been present or has it started recently?
- If it has started recently a motor bearing may be worn and in need of replacement.
Are their specific regimes of flight where the problem is specific?
- Close to the ground (takeoff / landing) , high throttle, low throttle, heavy bank,

I’m running a dji flame wheel f450, I’m using the dji e300 propulsion system with the self tightening props size 9443 and I’ve used the thrust boosted 9450 props. I don’t balance them because they are always balanced right of the package. I’m running a 4 cell 7200 mah turnigy lipo which gives me 16 minutes of flight time at 100 meters high, I get about 18 min if I stick to about 40 to 50 meters high… It happens when ever I take off from grass, even happens on my naza-m v2 systems on my other f450 and my f550. I kinda think it’s a too high of gains and I was going to try auto tune on my pixhawk f450 to see if it helps… It happens only on slow take offs and lands if on grass. If I arm the motors and slam the throttle stick straight to 100% it won’t happen but then again it doesn’t have a chance too! lol… As of now I don’t know which log file is from when I took off from grass cuz I been making sure I was on pavement lately but next time I fly I can do I grass take off and landing for you and send you my log… Maybe you can help me with these slow loop lines I’m getting in my logs, under the pm test, it keeps failing because of it…