Sam I am

Searching through the forums I have noticed many people use dynamat for sound control. I am wondering if anyone has used anything else and how well it performs?

Macfreak007

I wonder the same thing, I need a replacement sound covering for my rear hatch area, under the carpet, the transmission is way too loud! good question!!

The_Phantom

I was able to reduce the interior souond levels of my 944 by 10 dBs as measured by a radio shack SPL meter. What I did was remove the seats and carpet and put down four layers of dynamat extreme, put a foam pad in the trunk under the carpet and switched to Bridestone Potenza RE 950 tires, oh and I also filled the hollow cavities where the rear spakers go with foam. When I get the chance, I will also probably undercoat the wheel wells with dynamat spray undercoating and probably undercoat a lot of the rest of the car too.

My advice is to buy dynamat extreme. Original dynamat is terrible by comparison. You can get it very cheap from audioetc1.com. The bulk pack that crutchfield charges $249.00 for (http://www.crutchfield.com/S-Rpc4OY9...search=dynamat) is $131.00 at audioetc1.com (http://audioetc1.com/product_info.ph...cts_id/107990). You should also throw a foam mat under the carpet in the trunk. Check out the dynaliner (http://audioetc1.com/product_info.ph...ucts_id/107991) or the tack mat (http://audioetc1.com/product_info.ph...ucts_id/107994)

To really make a difference it will probably take two of those bulk packs. Dynamat is not cheap but it does work.

The_Phantom

Also make sure to get a roller tool to help you install the dynamat. The wood ones are better than the rubber ones but it looks like audioetc1.com only has the rubber ones: http://audioetc1.com/product_info.ph...ucts_id/107973

ninefiveone

If you had to guess, how many lbs of dynamat did it take? I've never had the stuff in my hands so I've no idea what it weighs.

Mike1982

Mass: 0.45lb./ft2 (2.20kg/m2)

From cruthfield info.

The_Phantom

The audioetc1.com website says that each bulk pack weighs 25 lbs. which seems about right to me (the weigh of the packaging is negligible because it is just a bunch of dynamat in a cardboard box that weighs a pound at the most). I'm pretty sure I used three bulk packs which would be 75 lbs. total in my case, but it was worth it. Also, I forgot to mention to you guys that I also removed the door panels and put like two or three layers on the outer door skin. Oh and I used a dynamat hoodliner which helps a little with engine noise, but didn't make a huge difference: http://audioetc1.com/product_info.ph...ucts_id/107995 .

Sam I am

Fishman,

What kinda of foam did you use in the speaker cavities?

ErichCS

This idea sounded good to me, until you said it was 75lbs of weight added to the car. That's a lot of weight for these cars. I would think there would be a noticable difference in all around performace.

I hope Weight-saving-Manning doesn't see this thread...

-Erich

The_Phantom

I used DAP foam. I'm not sure if it was the best kind for the job, but that's what was available to me.

The_Phantom

Yeah, maybe people that track the cars would notice the difference, but I didn't.

Robby

I was all about this until I saw the weight too- I'll bitch more than Manning ever will....


Ok, seriously... Fishman- what kind of #'s did you get before & after? Did you do any tests after installing just ONE layer of the D-mat? I'm thinking the first layer would probably do more than ~2/3 or so of the total noise reduction- law of diminishing returns...? Did you get any #'s while the car was moving?At highway speeds- 80mph or so? Four layers of that stuff would be a good 3" thick I would think- how were you able to get the regular carpeting back down over that? What about the door panels, or, did you just leave them off? That stuff is THICK....

How much of the car can you cover w/one of these bulk packages? Also, did you remove the rear seat bottom & do anything under there? That would be one of the best places, I would think, as well as the hatch, b/c the tranny DOES introduce a TON of noise.

BTW- I've been told that coating any &/or ALL exhaust parts w/HPC, or, Jet-hot coating, etc, will make a tremendous dif, but, I have nothing to back that up with... exhausts in these cars, especially aftermarket, can really be noisy- my SFR makes it almost unbearable, but, I'm hoping to do something about that soon.... welding in extra mufflers & replacing the Bullet w/a new muffler that Turbo Tim has which is queiter.... Hopefully can sell my Bullet muffler here for a few bucks to offset costs...

The FOAM you put in the rear wheel wells- was that a spray foam that hardened up & completely filled them, or, did it just coat them? I'd love to hear more about that b/c I'm interested in doing some stuff back there myself- I have some neoprene rolls- the kind campers use to lay their sleeping bags on as thin mattresses. It's ~.75" thick- I'm hoping a layer of that in the rear might help, but, am afraid the density is not quite enough to REALLY matter- considering thin Dyna-Mat & the neoprene on top- it's REALLY light stuff....The thicker, real, Dyna-mat would work better than the thin, I'm sure, but, I'm wondeirng if the difference would be worth the extra weight...?

Last, the spay-on Dyna-mat- does that stuff work well? Could one coat the INSIDE of the wheel wells, doors, etc, to help at all? Would that stuff dry to harden, or, would it be a more rubberized finish? I've never seen it in person before, so... I'm also wondering how much weight IT would add...? It would obviously depend on how much was used- how many coats, etc.... but, it could probably be sprayed on both the inside AND outside of the car....? Again, wondering how much would be good in comparison to the amount of noise reduced, etc.....

Anyway, I'm very interested in hearing more about this.... glad to hear that someone has really tried to do something in this area... thanks for posting...



Hugh- check this out when you get time....

http://www.zeckhausen.com/testing_brakes.htm

It's a really cool test on brakes- they used a 350Z & put several brake kits on it, etc... I think you'll find it interesting.... I thought it was really cool... one of the best brake experiment tests I've seen.... Evidently, front to rear piston size has a lot more to do w/things than meets the eye.... just thought you might appreciate it, based on our earlier discussions...

The_Phantom

Ok, as I said I used the Radio Shack SPL Meter (here is a link to the exact model- http://www.radioshack.com/product.as...%5Fid=33-2055).

I set it to A weighting (not C weighting) and before having used any sound proofing got numbers in the mid-eighties, like 83, 84, 85 dBs.

No, I did it in two stages. The first stage I put down generally two layers and then later went back when I put in a new amp and had the seats out (my car stereo amps are under my seats) I threw down two more layers.

Yeah, something like that. I think that the first two layers reduced the noise by probably four dBs while the secone two was more like 2 dBs.

Yes, I drove the car on the same road before and after in all cases at the same speed (about 60 MPH since that was the way that either road and track or car and driver tested cabin noise in their magazines and I wanted to be able to compare it to those cars too). It was mid-eighties to begin with and after everything the readings were 71-72 dBs.

No, I can see why you might think that but after you use the roller over the dynamat extreme each layer is a quarter of an inch at the most, so four layers is only an inch at the most and the carpet fits fine.

With one layer you can easily cover both doors, below each seat and the entire hatch area and still have some left over for a second coat in some areas.

Yeah, I dynamatted under the rear seats and that was a mistake because they don't snap down perfectly like they did before. They look fine when looking down at them but there is a half inch gap (when the front seats are out) when looking at the rear seats from eye level

Yes, it wasd DAP expanding foam and it did expand and completely filled up the cavities unlike the undercoating which justs coats. I also drilled small holes in the door jambs under where the plastic piece is and squirted the foam in there too. If you fill up the back cavities, be ready to plug and holes where the door latches to the car. I had foam leaking out and had to plug it in my car.

I think it is unless you track the car.

I also insulated my suster's Honda Civic and we put a few layers of dynamat extreme on her front wheel wells and then sprayed the undercoating over them (we didn't have time to do the rear wheel wells). In her car, that made a 1-2 dB difference. Which isn't bad since we never got to the rear wheel wells.