RE: motor makes grinding sound w/heavy load
hi there from Toledo:
The grinding noise is indeed a timing issue between the ESC and the motor for the prop of interest. I had a similar issue with a ccphx60 and an AXI 413016 a while back. The great guys at CC told me to set the ESC timing at minimum (or low) timing, the issue went away. Every thing has worked great since. If you can adjust the timing for your ESC then by all means do so.
ciao -rjf