Sound / insulation

[jestr73]

What is the best product/material to use under the carpet for sound and insulation.

[ZIII]

If you do a search you will find dozen of suggestions regarding how best to insulate a Z.... many have written about Second Skin Audio who have a number of different products depending on what you want to accomplish and how much insulation you require. You can check them out at:

http://www.secondskinaudio.com/cgi-bin/index.cgi

Good luck....

George

[EScanlon]

A combination of materials and not just ONE product.

There are folks who swear by Dynomat, others Brown Bread, others the JC Whitney stuff, and even amongst them there are differences of opinion.

When I used to sell suspended ceilings, we approached a noisy office with the type of ceiling tile used, then the type of sound insulation on top of the ceiling tile and lastly with sound batts hung vertically in between the office partitions. This did a lot to reduce the noise coming in over the ceilings (and you'd be surprised at the amount of noise reduction) but it did little when the noise was actually being transmitted through the walls!

So, taking that into consideration, you need to apply something to the metal to dampen harmonic vibration due to engine and road noise being transmitted through the metal. Whether you use tar-paper (as the factory did, and my choice since it's cheap) or you go for something more esoteric (such as Rhino-Liner, or some other Pick-Up Bed liner material), the key is to get the metal to vibrate as little as possible. Just be sure to protect the metal before you apply any material, whether Brown Bread, JC Whitney, Rhino Liner or Dynomat, none of those are designed to protect the metal from rusting. For that reason people oftentimes coat the floor pan with POR-15, then cover it with their product of choice.

This reduces the STC (Sound Transmission Coefficient) of the metal.

Next, address some form of padding...carpeting does well, but it will do even better with some form of open weave material, which is why the factory used "horse hair", which is simply jute. Only problem is that it can and does absorb water...IF LEFT TO SOAK IN IT. Good Jute has had an oil sprayed on it to keep the water from readily soaking in. Unfortunately, after all these years, the jute in your car is getting close to being just thick felt and can and will absorb water. If you decide to go with the modern equivalent, which is a kind of sponge rubber, be sure you get the CLOSED cell variety. It's spongier (the air doesn't whoosh out of it) but it won't allow water to rush back in and fill the cells when you let off the weight.

This "soft" insulation increases the Noise Reduction Coefficient (the amount of reflected sound).

Done properly, you can even get away with an old AM/FM 4 Watt Monaural Radio and it will sound LOUD!

FWIW

E

[jestr73]

Thanks for the information. It will be very helpfull.

[hls30.com]

I'll second what Enrique said. I will be using seven different products to take care of ambient noise in my Z. Togerther they are taking care of noise by manipulation of fundamental harmonics, reflection, conversion and absorbtion.

Will

[Craig Lovegrove]

I have a V8 in my car and used to find it very loud inside the car.

I lined the whole floor with black foam rubber about 15-20mm or half inch thick under my carpet. Even did the fire wall. Then I brought a blank foam matteress about 4-6" thick and proceeded to stuff it into ever pannel in the car from the rear quarters, side walls, even under and behind the consol. Now the car is ever so quiet not to mention keeping the car a little cooler on those summer days. Plus I plugged up every hole in the rear quater and fire wall which also stopped any fume problems. All this worked fantastic for me and pretty cheap.

Good luck.

[beandip]

I used a product from a Company called B-quiet. It is called ultimate and I covered approx. 75 sq. Ft. inside my 240. It is a tar type of material that is foil backed and is self sticking , you just peal off the back and expose the adhesive. It will not absorb moisture and is easy to apply. It comes if a roll. I bought two 50' rolls. It can be cut with scissors or razor knife. I covered the floors , firewall , cowl , inside the doors and inside the rear fenders and hatch where I could reach. All those areas were first covered with POR-15 . I used a layer of matting I bought from JC Whitney , its about 3/8'' thick and is foil backed on one side . That went under the carpet in the hatch area and foot well. I also used the ultimate on the back side of the plastic trim panels in the hatch area. As was mentioned about the original radio being sufficient , this is what I kept. I did use the ''horse hair'' on the firewall too. I found some in great condition . My Z is reasonably quiet for the type of car that it is. I didn't expect the noise level to be that of a BMW, and it isn't. She sounds like a sports car . But I can enjoy the radio and or have a conversation with out any problem. I would be careful using mattress foam or any other open cell foam . They will absorb moisture for sure. Gary

[EScanlon]

Craig:

Don't doubt it worked for you, as you eliminated any cavities in which the sound could resonate and reverberate.

But in this case, unless you took measures to ensure you were inmune, I think the cure is going to prove to be a disease carrier.

I'm presuming you don't get much rain or drastic drops in temperature with the humidity way up high or you wouldn't have stuck a huge sponge in every cavity of your car.

Most foam mattresses are mostly open cell construction. That's because the manufacturer's fully expect that the person sleeping on them won't want to wake up drenched in their own perspiration. If the foam were indeed CLOSED cell, that's exactly what would happen.

And even with a material that is decidedly made up of closed cell foam, it's not a good idea to inject it into the interstices of your car if there is any kind of moisture and temperature variations in your neck of the woods.

The changes in temperature alone will ensure that at some point in the day the metal of your car will have SOME moisture on it, and it is air movement that allows water to evaporate. If you close off the space, there is little to NO air movement and therefore....RUST.

The problem is basic, put something that retains moisture...even just a few drops...in contact with metal, and unless that metal is protected with a perfectly NON-porous coating, you're going to get RUST.

That's the main problem, the retention of the moisture for an extended period of time.

FWIW

E

[BD240Z]

I used a product called "Quiet Car" in my 280Z and the results were impressive. It comes in 5 gallon pails and is applied with a brush. I did the complete inside floor and the insides of the doors. When I was finished, the doors shut with a solid thunk and the road/engine/exhaust noise was cut way down.

The only drawback is that it does not self level and has an uneven surface when dried. This didn't matter in the 280 because the floor carpet is secured and the floor would never be seen.

I've already used Evercoat's Q-Pads for the floors in my 240Z but I'll use the Quiet Car in the doors and any other cavities I can reach with a brush.

More info can be found here www.quietcar.net

Bruce