I'm gonna throw some dynamat in on my hatchback, get rid of some of the rear rattles. The only question I have is, With my hatch it's like 2 layers of steel with a large air gap between the two and a few large sized holes.

With the Dynamat, should I just do one large piece over the outer bit of steel covering the large holes, or should I cut out the holes and put that cut out piece on the inner sheet metal.

There is no way for me to completely cover the inner sheet metal, as the two pieces are welded together, and the only way to access it is through the few large holes.

I'm thinking I should just ignore the holes, and put one or two layers of Dynamat on the outer sheet metal and be done with it.

thoughts/opinions?

 

Foam between the ribs and outer sheet, trim excess, apply dynamat...

 

u dont cover the outter sheet metal at all

cover only on the inside, covering all the holes.

 

Thanks dude, Any kind of expanding spray foam work?

 

Low expanding foam works best. I use "Great stuff" expanding foam.

 

Mono foam in my experiences hold water and rusts the out of your vechile. Just a heads up.

 

So these are the holes I'm dealing with




With all the wires running in, do you think I should still foam it up? There's quite a large cavity to fill. It's not just simple ribs.

 

Kind of along the same lines as whothennow's post, but make sure you use a heat gun and roller and really form the dynamat to the metal and make sure it's all pressed nice and tight against the metal. It should look almost part of the metal when you're done. Otherwise (much like the foam) the gaps can trap moisture and moisture leads to rust