I did a search but didn't come up with much.
I've tried tightening the center crew but it doesn't really help, vibrates so bad while driving its almost useless.
Do I need to remove the screw and put a small washer so the screw can tighten up on it?

 

Ordinarily, the mirror shouldn't be shaking that bad. Mine is fine. You might want to find out why your car is vibrating so badly.

 

Fixed it. I found another thread you had done on removing the mirror that had some pics.
I pushed it back up into the sliding bracket and tightened the screw, all is well now, thanks.

 

Hmmm. I'm glad I was able to help you though I didn't really help you.

 

Mine shakes between the mirror and the base, the interface which pivots (breakaway feature). I've had many honda/acura products, and it seems to be a common trait.

Inside there is friction material and an indent. As the friction material wears or perishes, the mirror is left without on-center material and small rotations occur over bumps. Not a serviceable item, the only reason I know is I broke a mirror years ago and tore it apart to see inside.

Back to the S2000, I was able to dampen the vibration using a rubber band to fill the gap. I selected a yellow band for my yellow car. Solved the issue for both mirrors. I suppose those rubber bands will also perish, I'll just keep adding a new one.