I got this weird rotational grinding sound when reaching the 4 500 rpm at any gears. I haven't noticed it on the race track. It was on the way home that I have notice this sound. The sound does disappear when I press on the clutch.....It doesn't sound like your typical main bearing. I inspected the tranny recently and everything was good (changed the main bearing). I only drove 1 200 km (745 miles). I must admit that I did have some bad gear changes. I have a Type-R tranny. What could this sound be and is it still safe to continue on the race track?

 

by main bearing do you mean throw out bearing?, could be the pilot bearing that the input shaft sits in.