Sound Deadening Questions

[fiftytakedowns]

HEy,


Being in the process of building my 2002 I was curious as to how I would deal with the interior noise. This car is exceptionally noisy, which I enjoy when it is the engine, but not when it is rattling here and there.

Essentially after searching I found some interesting discoveries regarding sound deadening.

It seems as though the purpose of sound deadening with products such as dynamat is to keep the metal from vibrating so much. This makes sense and i understand how it is functional, but what doesnt make sense is why would you line the entire interior of the car with it, if that isn't what it is used for.

I feel like there are noise blockers, and vibration dampers.

The reason I bring up this point is because I am trying to save as much weight as I can with the 2002 and would love to minimize unneccesary sounds and rattling in the doors, floor trunk etc.

Ive seen products like second skin , and ultimate sound damper showdown, but I am sort of confused as to what would be maximum dampening for least amount of material/ product/ weight.

I feel like There should be a like list of what would be most effective such as:

Doors:

Floor:

Dyanmat? Second skin? etc etc...

Firewall:

SunRoof:


Trunk:


Input of what worked and what didnt?

[AndrewBird]

There is some good info in this thread:

http://www.r3vlimited.com/board/showthread.php?t=210370

[e30iwite]

Do not use dynamat as sound or noise dampening. I speak from personal experience. I had used it to cover the ENTIRE (floorboard, ceiling, firewall, you name it) cabin of my toyota tacoma. Here are the reasons why you shouldn't use it:

1. expensive (overpriced)
2. Too difficult to use (the aluminum foil cuts your hands up and it's so sticky that once it is applied, it's nearly impossible to get off)
3. Too heavy (horrible mpg, handling and braking became terrible)
4. does not dampen noise (it's a tar-like material that keeps panels and screws from vibrating, but is NOT a good material for acoustical dampening. Although it does possess some acoustical dampening properties, there are better options.)

If you're wondering why the fuck i applied so much damn dynamat, it was when i was in my crazed audiophile mode. I was running two square L7s and mb quart speakers tied to two hifonic amplifiers 1600 class D mono and class A/B 170x4 channels.

For my e30, I'm currently running 4 coaxial Polk audio speakers (5 1/4) tied to the 4 channel hifonics amplifier I mentioned above. Still contemplating on putting the sub in the trunk. Don't wanna add the extra weight and doesn't need it. The Polk audio speakers are that good. It's so clear and bumps that hard. Of course, they don't bump as hard as the L7s but adequate enough that a friend thought I had installed a small sub in the trunk.

Okay, I've been doing some research on how to noise dampen the e30 and found out that open cell foam is the wall to go. there's also closed cell foam, but open cell dampen sound better. Dynamat actually sells foam pads but at an outrageous price. I found a company online that sells large sheets of sound dampening foam at different thicknesses for cheap. This is how i plan on setting up the e30. their website is foamforyou.com. scroll down on their left panel to find noise control foam. it should bring up a page of all types of foam. Scroll down for the large flat sheets.

I plan on cutting the sheets into smaller pieces and gluing them directly onto the panels beneath all the carpeting. I'm still contemplating on taking off the dash to apply this foam to the firewall. I've seen pictures of somebody's dash removal writeup and noticed that there is actually a thin sheet of some type of sound dampening material behind the firewall. But I think the factory sound dampening material is inadequate. I'm probably gonna go with 1/4 " thickness on the floorboards and 1/8 " thickness for the doors and ceiling. If anybody decides to go this route, make sure to make a post on the quality of the foam and noise dampening property. I'm not going to be doing this project until next spring.

[lbreevesii]

You're dead on about what the foil backed products are for- taming vibrations and panel resonance.

Check out soundeadenershowdown.

I used their CLD tiles(like an extra thick dynamat) to reduce panel vibrations in the doors, parcel shelf area, and roof. Since you only need 25% coverage to do what they're supposed to do, you save a lot of money and weight. I'd say I added 8 lbs tops, and I heavy handed it.

I bought(but ended up not using- and its for sale if anybody wants it) a 1/4" thick(but compressable) thinsulate material to put above the headliner.

Granted my car is extra noisy thanks to the buzzy M42, noisy diff, and a cobbled together exhaust, but I feel like I will want to go back and use a foam decoupler and a mass loaded vinyl to actually block out some sound. I don't want to make it modern beigebox quiet, but I do want to tame things a bit.