Insulation that reduces vibration
 

Hello!

As some of you know, I have a lumber rack on my truck. Somehow, the aerodynamics of the front bar, coupled with the cab lights, makes the roof vibrate. At freeway speeds, this vibration gets bad enough that I'm getting a humming in the cab that drowns out the engine.

I know that the rack's doing this simply 'cause the vibration/noise disappeared when I had the rack off to paint it. I currently have the headliner out (needs to be re-covered), so I'm looking right at the bare painted metal of the roof. Before re-covering and re-installing the headliner, I'd like to get some insulation on the roof. Is there a good material out there that's designed to minimize vibration? IIRC, Dyna-Mat's designed to do that for speakers, but I could be wrong there.

Any thoughts would be appreciated...and, on top of the vibration reducing stuff, I'd like to put some noise/heat insulation in.

Thanks in advance! :)

...anyone?

Won't tell you that Dyna-Mat's a sure cure, but seems like a good way to go. I've used rubberized roll roofing for essentially the same thing in my VW's - mold it with a heat gun - it's much cheaper than Dyna-Mat and you'll need a lot. The best it does is to dull the sound, but a big improvement in something like a Bus.

Use some product that will stick to the roof during the hot summer. Read what Dynamat and it's brothers say on the packaging.

All you want to do is change the resonant frequency.