Originally Posted by nunzo
This may sound weird but....1)I have my zumo mounted to the dash behind the shield on my 08 990. I installed a reinforced piece of aluminum mounted to the headlight frame assembly when I had the bike apart. This brace definitelysecures the dash due to weight and vibration. 2) I used a Ram mount with rubber between the base of the mount and the dask.
The weird thing is that when i am tooling around in gear (NOT 1st GEAR) and my revs get to around 2800-3000 the vibration of the zumo mandates a downshift to the next lower gear and at 3000 rpm or higher, the unit has no vibration is as smooth as glass (kind of).
I assume others expereince a smoother ride at higher revs and by keeping the bike in the 4000-6000 range.
Unfortunately what you are experiencing here is the natural resonance of the bracket setup you have and it is being excited by the vibration created by the engine. What you can do to aviod it is probably try a less rubbery bit of rubber if that makes sense, this should stiffen it up and help the problem.