Automotive Sound Dampening

First things first, peel out your OEM interior. We did it to our 2002 Subaru Impreza WRX one compartment at a time. You can break an all-day sucker into a one-hour sundae, and get back to the project when you have the clock necessary. On our list was the easiest section—the trunk. It required us to remove all trunk accouterments and the rear seat backs, uninstalling as many parts as possible because everything that's out of the way leaves more uncovered metal and raw surfaces available for matting. The targeting strategy is not complicated: every dense, hard or stiff body panel that is capable of vibrating, rattling, resonating or shaking at a high rate benefits from an application of sound deadener. If you properly cover the core elements of your car's metal body, everything inside should be isolated from the sound-producing vibrations and thusly quieted.


Once the sheets of sound dampener have been heated in the driveway to a mushy, workable temperature (leave them there too long and they'll be too hot to touch), it's back to kindergarten. Cut and paste. Work with bigger sheets (initially avoiding small pieces; bigger pieces mean better vibration control), and try to avoid having a chunk of matting that bends around a sharp angle. Make those hard edges your cut-point. You'll hear various trains of thought from the "pros" about how and where to install sound sheeting, but the core importance is to cover as many hard metal surfaces as possible. The matting is easier to work with when in big sheets, too, so perhaps the where and how of installing the deadening material can as much be dictated by the facilitation of the use of these overlarge pieces as anything else.


The use of a heat gun (any hardware store, many electronics stores, most hobby stores) is essential for the tar/rubber sound dampening sheets. Heat the sun-warmed material after it's been laid into place to the point of super elasticity, not melting, but too hot to the touch. You want the sheets to change dimension and size to match all the nooks and crannies of the body panel, pliable and moldable without resistance. Roll the dampener into place heavily, not worrying excessively about minor splitting as long as the material is stretching into place easily while showing no tendency to return to its original dimension, and covering all metal contours. This is not difficult; it just involves a little patience and a forearm workout. Don't be unwilling to climb right into your trunk to make sure you've got the necessary leverage.


You'll notice the presence of many leftover chunks of matting after cutting the large pieces to shape. They're perfectly usable, though we may have gone overboard in seeing that none were wasted on our WRX. Two of our 3x5 sheets of installer-sourced industrial-grade sound dampening were used in this installation, so there were a good deal of little snippets available for filling the uncovered spots between larger portions. In the photos with this story, you'll notice several spots where the dampening material was pulling up—a perfect indication that we'd not heated it enough before rolling. Go back with your heat gun and wheel and do it again, thoroughly. One of the charming facets of this material's composition is that the dampener breaks down before the adhesive, so you can heat the sheet until it stays put and know it'll stick around.


It's not hard and, if you don't mind taking the interior apart, you can go to town with six or eight sheets of sound deadening material, quieting the vibration and noise that can otherwise befoul the acoustic loveliness of your motoring experience.