Universal mirrors vibration after 40 mph

[Spyke]

I took of my front end nose to put wider bars on and put universal single bolt mirrors on but any speed over 40 mph the they vibrate . I can see if anything is behing me but its certainly not clear . Is there anyway to stop this ,like rubbers or a hammer 

[robbo]

Is the vibration coming from the bars as heavier bar end weights could be the answer, or lead shot or similar material to take the resonance out of the bars.