LG Tromm WM2277HW during high speed spin makes noise
I had exactly the same symptom...grinding noise only during high speed spin cycle.
I took the top and back panels off to see how the drain hoses etc. connected. Not wanting to take it apart further, I eventually just took the washing machine outside (I knew I was going to be dealing with water!), pulled the debris catcher front side bottom, and let rip with a garden hose inside the drum with the catcher out (leaving an open drain that could flow unimpeded).
Water flowed quickly out of the open drain, and lo and behold, a small drill bit came out with the water flow. This bit, presumably had gotten through the drum grating, and was resting on the bottom of the housing, scraping and grinding when the drum was spinning.