With the fine weather is just over the horizon, I've got myself a couple of pairs of Vifas for the doors and some Audax neodymiums for the HF pods, and will be starting the install soon.

However, I'd like to do some soundproofing first. I notice most noise from the engine at lower speeds. Then I get road noise at higher speeds. It's very difficult to tell where the noise really is coming from, but I do notice that there is less when I have a full tank of fuel, and the car is quieter when the trunk is full.

Has anyone tackled soundproofing in a reasonably scientific way? I don't mean just plastering 10 layers of Dynomat all over the place. Where is soundproofing most effective? What about the multilayer soundproofing materials you can get? Are they worth it? How can you reduce engine noise?

Any tips would be greatly appreciated.

Stevie

 

try these:
http://www.cardomain.com/id/sweetsound2001
http://www.cardomain.com/id/sweetsound2002

and this:
http://www.cureline.net/lex/audio/howto_mat_install.htm
more:
http://www.cureline.net/lex/audio.htm

First two links of my personal cars..Other two are Pete. He's a member here (Retrodrive).

Enjoy...

Anton

 

The critical parts for the road noise are the wheel wells and roor seals. You would have to use many products concentrating mainly on different kinds of foam and sprays. RAAMmat (Dynomat Extreeme) is a good base for your project. Also use some truck bed coating in the wheel wells.

 

Anton and Pete, what can I say? Excellent information.

Unfortunately, I don't have your skills. There's no way I would even dream of removing the headlining in my car. Even removing the seats is something I would be very nervous about tackling.

So my question to you is, where does soundproofing make most difference? I have started to do the trunk, as it is the easiest. I've got about 10 pounds of bitumen damping on the floor there now and I can't say that I really hear any difference, even though the trunk floor panels were quite resonant.

Stevie

 

Not so easy. When we went to modern CAD design, we found we could increase strength and reduce weight by taking metal out but being smarter with the metal that was left. Generally, chassis parts are designed with appropriate stiffness by putting in some structural changes to keep stiffness with lower weight. Every bend and dimple is designed in to keep stiffness. It is just amazing if you ever look at the deflection properties of a sheet of steel or aluminum by itself and then either bend or weld in a hat section (a u section). The stiffness goes up dramatically. So, you have two ways to get noise, either resonances in the metal or just transmitted through the metal because there is not enough inherent damping ability. For the resonance issue, look at the largest, flattest pieces of sheet metal and start there. How much and what kind of sound deadening do you need? Who knows unless you can model the whole chassis and all the properties of the sound deadening materials it is going to be trial and error. There are sound deadening sheets that go up to around an inch and a half thick that I have seen for various applications. The trunk probably has the largest flat runs of sheet metal that we have to contend with. Now if the noise is not strictly due to a resonance condition but just transmission, that one is a bugger. I think that some of the modern sound deadening materials are quite good but you probably just have to get as much as you can whereever you can. It is hard to think of any area that is more inportant than another but if the noise is engine related (hard to believe, my engine can hardly be heard) you need firewall and floor pan where exhaust pipes are routed along. Tire noise, wheel wells. I have only done the front door panels on my GS so far but the back doors are next up (hopefully this weekend) and then the sub. When I do the sub I think that involves taking out the most interior so I will really look at using the CAE materials then. I already am planning on the rear deck and the bulkhead and any other areas of opportunity that present themselves with the material I have. One thing I can say is that you really need to get the materials down flat and well adhered with no bubbles. You might take a step backwards otherwise.