mike cap

I would certainly pull out the old cardboard sound deadening material. It will eventually curl and fall off and rattle around in the bottom of the door. It also collects moisture - a bit of a crap product to use.

Just wipe the interior surface with some thinner and apply the Dynamat over the glue residue. No reason to remove the old glue - the Dynamat self adhesive is fantastic and sticks to the surface well.

pp000830

Dynamat. I think similar stuff may be sold at DIY stores without the adhesive backing. A little spray adhesive on it may work well at lower cost.