Since our cars began showing up early this year, there have been a few posts wondering if adding some kind of sound deadening to them would make a difference. I've had very good luck doing this in other cars (some with
amazing results, so I took a shot at it with my fortwo.
I started thinking that I was just going to do the door panels in order to give my new speakers (Polk db675s) a more acoustically-neutral environment to work in. But as I started poking around, I found that except for the foam molded into the rear half of the carpeting, there isn't any sound deadening in the car. It just adds weight and cost, right?
I didn't worry about adding a passenger worth of weight to the car, since I've been using B-Quiet Extreme material for some time. It weighs 0.30 lb per square foot-so a 50 sq/ft roll weighs only 15 pounds. It costs around $90 a roll. I also like this stuff since it comes in 1 foot wide rolls, making it easy to work with, and I've found that the adhesive is better than other brands I've used (especially Dynamat's overpriced stuff). Once it's on, it's not coming off, even on vertical applications.
I made almost a hundred templates doing the job (sorry, they all got tossed out with the backing paper) and covered the entire interior, starting with way up under the dash and over the wheel arches, and going to the rear and up the sides to the roof. Most surfaces have two layers of material, as a double layer will yield 3x the vibration damping of a single layer. The door skins and the very top of the Triton only got one. A second layer on the roof frame would not have reduced wind noise, and the one layer on the plastic door skins made them far more substantial feeling than they were when I took them off the car. I did put two layers on the inner door and the metal frame, since the speakers were directly mounted to them. I'm very happy with the bass response of the Polks and with the amp, they play very loudly.
So, did it work? Not as well as it did on our Passat, which my dad thought was quieter at 80 than his new Cadillac, even though the VW has a sport exhaust and super high-performance tires. But the first drive around the neighborhood made it obvious that there was now very little sensation of road noise from the tires or through the suspension. It doesn't come close to eliminating engine noise, but there is much less mechanical din coming from behind the seats. On longer drives the project really paid off. An hour drive is sort of relaxing in the high, firm seat, where before I wasn't exactly frantic to get right back into the car.
I took it to our smartcenter and drove their passion coupe demo, and then retraced the route (15-20 minutes) in my car. Once we moved into my car, two things were apparent. Below 40 mph, my car was clearly quieter, especially where pavement textures and bumps were heard clearly in the demo. Once at higher speeds, the lack of road noise drew your attention to the wind noise. But the majority of what was heard was wind noise. The other thing is that in the rain, the car is very solid sounding, since the constant splashing and pattering sounds of the water is far less, and nothing like it's splashing on a tin can under you.
I'm extremely happy with it, especially after putting in about 50 hours to properly do the job. It's definitely not a project for a first-timer, and I doubt anyone would pay a stereo installer to do it. I've wondered if it would have an effect on making a sport exhaust more livable, but since I need to sell it, (it's in the For Sale threads) maybe the next owner can find out.
1 - Kermit
3 - The Street Rod
4 - Split Window Vette
5 - The Veggie VW
Today
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