Sound Insulation/Dampening

[HAZ-Matt]

Hey... I don't usually come over to the stereo section, but I figured you guys would know the most about this.

What I want to do is decrease road noise and the volume of my exhaust inside the car. I've read a few posts about dynamat, brown bread, spray in liners, etc. but most seemed to be concerned with reducing rattling. What I would like to know from anybody that has put some of this material in their cars if it reduced road noise sufficiently to warrant the added cost, weight and effort? I had read on another board about a guy who put a bunch of stuff in his Accord, and claimed to have only reduced road noise around 7% (his estimation, probably an exaggeration). The point is that if it isn't noticeable, I'd rather not undertake this project.

Thanks

[Brian Dieckman]

Dynamat (and related materials) reduce vibration by dampening it with weight. You probably knew that.

I've installed about a zillion stereos and only five or six I can think of spent the money for a full chassis dynomat job. Here's why:
1. The stuff is EXPENSIVE
2. You have to remove every panel in the car, including carpet
3. You have to CLEAN every square inch of the area you're going to cover
4. You have to use a heat gun with several of the products, in order for them to conform to bends and curves.
5. You have to be VERY CAREFUL what you cover, so that trim panels don't bulge, and you don't cover and important holes, clips, wires, connectors, vents, etc
6. You have to put all the panels back, and a lot of the time, they don't fit because you got some of the stuff in the wrong place.

After the first DM job I did, I set a flat rate of $1500 per car, just cause it was such a pain in the keister.

Pain, huh? I do have some good news, though. In the Hatchback cars like the f-bodies and fox bodies (mustang) and the like, you can get about 70% of the noise by doing just the hatch area up to the seats.

The only thing between you and the road/tire/wind/brake/susspension noise in the rear of the car is a piece of plastic trim. You can DRASTICALLY reduce the noise from back there by coating the body panels behind those trim pieces, behind the spare tire area, the trunk floor and gas tank hump, and all the plastic that clips over those areas.

If you want to get crazy, pull the seats and the carpet and go underneath the seats up to the pedals. THAT will kill almost 100% of what you CAN get to.

If you want to do your doors you can, but it won't do much good. They're already dampened quite a bit, plus they've got that huge plastic/fabric door skin on the inside!

If you're looking to kill engine noise, Parts Express sells some stuff that you can stick to the firewall that is AWSOME!

If you do any of this, you'll notice a difference. No offence to imports, but there isn't much you could do to an accord to reduce the noise. (except dip it in tar)

If you do all of it, you'll feel like you're riding in a Caddilac. Trust me, it's worth the time and effort, I just don't know if it's worth the money!

Good luck!

-Brian

[HAZ-Matt]

<blockquote>quote:</font><hr>Originally posted by Brian Dieckman:
In the Hatchback cars like the f-bodies and fox bodies (mustang) and the like, you can get about 70% of the noise by doing just the hatch area up to the seats....

If you do all of it, you'll feel like you're riding in a Caddilac. Trust me, it's worth the time and effort, I just don't know if it's worth the money!<hr></blockquote>

I was only planning on doing the hatch area. Want to kill exhaust noise more than engine noise ;) I'm not sure it's worth the money either, hehe. Thanks for the input... Anybody else have an opinion they want to throw out?

[Reverend_Ezekiel]

I think that it might be worth it if you only did the hatch. That would eliminate most of the noise in our car, but doesn't cost as much as doing the whole car.

I'm a little curious about the spray on stuff, how well does this stuff work??

[Brian Dieckman]

*Some* of the spray-on stuff works the same way as the stick-on stuff. It adds weight to the surface, keeping resonant vibrations from flexing the panel. Some of the other stuff claims to convert the vibration energy into heat, (the rockford stuff, and it's cheap knock-offs) but it really is doing the same thing.

It's messy, and it can be a pain, but in general, if you like to tape, and have the equipment, the spray stuff works well for hard to reach areas.

The main problem is that it's really expensive, and you'll need to do several coats. The kits that have one can and claim to do two doors will BARELY cover two doors, much less multiple coats.

If you're just doing a trunk area, go for the sheet stuff. It won't really be that expensive, nor will it be too much work. For an extra added bonus, cover the inside of the plastic panels that clip over that area. They vibrate too!

-Brian