Reduce road noise on my Mazda MPV


#1

How can I reduce the road noise I get on this vehicle? My dad once put a layer of extra carpeting on the floor and firewall of an old Metropolitan with remarkable results. Would that work for a minivan? Should I just use some left over carpet?


#2

There are products, such as Dynamat, that can be applied to the inner body panels to reduce noise, but it’s not cheap or easy to do.

Tires are probably the largest contributor to road noise. I’ve had excellent results quieting a vehicle just by choosing quieter-riding tires.


#3

The only car I’ve soundproofed is my current Scion tC, and it made an enormous difference. The tC is known for high road noise, and now I don;t even turn up the radio on the highway.

There are basiically two types of nooise to deal with; one is the vibrations that travel through the structre and the other is the acoustic waves that move throughout the cavities.

Structural vibrations are dissipated by lining the structural and sheetmetal with “structural damping” material. Structural damping is a high density elastomer coated with a thin aluminum. It cuts with scissors and self-sticks in sheets. That converts the waves into low level heat energy and dissipates it that way. I initialy used “Second Skin”, but ran out and continued with “Dynomat” from PepBoys. They’re the same material, but the Second Skin is about 60% cheaper. I looked up directions on the internet on how to “gut” the interior. You may want to get the shop manual for the body. Interiors are made of formed panels that have a variety of clips, fasteners, and screws holding them on. You’ll need to find out where they are and, in some cases, the trick to removing them.

I also used “jute” as both a liner under carpeting and in the cavities, and a barrier between open cavities, which is a matting the same as that used under carpeting. You can buy it from auto carpet suppliers. I used regular carpet padding from Building 19, a discount store. “Jute”, while the name comes from a plant, is actually made from different materials. I tested mine for flammability, heat endurance (to 400F), and outgassing, and it passed all the tests.

I noticed a huge difference. Even the wind noise from cars passing in the other direction is severely muted. If I tap on my fenders now I hear a solid thud rather than a hollow sound. And I now set my sound system (stock) up completely differently. The rear speakers no longer resonate in the cavities, the sound is more pure.

I recommend doing this if the road noise bothers you. Do the research, plan the work, and give yourself entire afternoons to work until you get the hang of it. Gutting your interior for the first time takes patience and a bit of courage.

Good luck. If I’d have realized how much of a difference it would make I would have done it years ago.

EDIT: it’ll run you between $5 and $10 per square foot, depending on where you get the structural damper.


#4

One method of reducing road noise is applying an undercoating to the vehicle. This is product that is sprayed to the underside of the vehicle in a thick layer to reduce road noise. However, this product must be applied correctly. Because if it isn’t, it can promote rust.

Tester


#5

Instead of spraying it on the underside…It can be sprayed on the INSIDE. Just remove the seats and carpet and try not to plug up any necessary holes.