I’ve been wanting to improve the sound isolation of my car for some time now. A friend has just done this to his car, but since it had been a while since I’d seen him, I couldn’t tell just how much benefit he got from the treatment. Basically, a thin (but dense) sheet of rubber-like material with a backer sheet (vinyl or aluminum) is applied underneath all the finished surfaces, right to the chassis of the car. This serves to increase the mass of the metal, thus raising its resonant frequency (reducing rattles) and providing an even thicker barrier between the road and your ears (quieting the cabin).
My question is this: What should I use to do this? I’ve seen some potential materials here, but they’re pretty expensive. Have any of you improved the sound isolation of your cars? How did you do it, and were you happy with the results? I was thinking spray rubber undercoating, as it is cheaper, but it would be a pain to control the application, and it doesn’t fill or cover holes like the sheet stuff does. What should I do?
As an aside, if I did choose to go with the sheet stuff, I’d need to calculate the amount of surface area to be treated. Is there an easier (or more accurate) way to do this than guesstimating based on crude tape measurements? Thanks very much, everyone.
