steve_jones

Ive got some Dynamat, to use up , dont really want to go crazy with the stuff and go the the whole hog and cover the complete car in the stuff,

So my question is this, what are the mose effective places to sound deaden , in the car, im also getting vibrations from the doors on higher bass levels,

I am running Boton speakers in the doors, Infinty reference in the rear, and a pair of JL 10`s in the trunk in the corners ( although there not installed yet )..

Suggesions on a postcard

thanks

cessna

Trunk first, then doors.....

shooter82

don't know if this will help or not.........but here is what i did to my G. i did not use a lot of dynamat, but other material to quiet my ride.......it was lighter and the different materials addressed different sound paths.

http://g35driver.com/forums/showthread.php?t=50569

dannichols

Depends on what you are trying to achieve. Vibration dampening and sound proofing road noise are two different problems that require two different solutions.

Dampening - Dynamat extreme or similar competitor (non asphalt) in trunk & doors

Sound proofing - Acoustic foam and/or jute on floorboard, cubby area and trunk. Vibramat under hood. Spectrum II in the outer wheel wells.

My setup required 50 sq ft Dynamat Extreme + 2 gals of Spectrum II, plus about 10lbs of foam and jute. About 50lbs of added weight.

bjr

shooter82
I checked out your link. I have two questions.

Did you have to take anything apart on your doors to get the insulation and soundmat on the outer skin in there? The 350Z doors look different than yours.

Notice the big black panel covering up everything. If the G is built the same how difficult was it to remove? Is it attached to any window guides or anything else difficult?

Also, when you pack that much insulation in there how do you manage to keep it out of the way of the window working?

dannichols

YOu don't want to take off the inner door panel.. Four of the bolts hold the window guides and electric motor. It is really difficult to get things realigned again as the bolts on the bottom adjust the angle that the window goes up. If it is off you will get wind noise and have gaps that will allow water in when washing or raining.

You can put ample dampening material on the inside of the outer door panel by simply removing the speaker. In there you will notice a stock dampener piece that runs almost the length of the door below the reinforcement steel tube. You can add dampener below and in front of this stock matting. I added about 3 feet mostly concentrated behind the speaker area. I also covered the removable panel (the thing pictured black above, but it was silver steel on my car) with Secondskin Spectrum and about 4 sq ft of Extreme.

dannichols

Steve, you will only get so-so sound deadening from road noise using a dampening mat like Dynamat. It is far too heavy to use more than 50 sq ft of it IMO. Put it in areas that are near your speakers, especially your sub. Crank up your system and listen for rattles..another method to track down good places. Place about 6-8 sq ft on each door..split this between the inner door panel and outer. Because there is so little space between the rear wheel wells and the panels inside the car, you may also want to cover them with matt.

But if you're looking to reduce road noise you would be far better off going with an insulating and sound absorbing foam or jute combination. Do the floorpan, Cubby, and trunk in this fashion and you will be amazed. As it is you would be surprised to find out how little sound insulation the floorpan has. If you get a chance, remove the seats and take out the stock carpet. It is wafer thin, and below it is mainly the stock sheet metal and then the road 7" below. I coated the back of the stock carpet with neoprene and then added Liquid dampener, open cell foam and closed cell foam to the floorpan. Worked wonders.

FCallender

I agree fully with dannichols. There is no useful insulation on the floor pan behind the seats (the cubby area) and over the wheel arches. Anything that deadens the vibration in these areas helps a lot. I used an asphalt based stick on material from Parts Express and it really quieted road noise back there.

bjr

Did anybody re-use the thick factory padding in the cubby areas along with what you are adding or is it pretty ineffective at killing road noise?

dannichols

The thick pad on each side of the cubby is useful. Keeps the sound of the fuel pumps and some road noise limited. Actually similar to composite products like V-comp annd L-Comp by B-quiet. The jute acts like a decoupler to lift the thicker vinyl away from the sheet metal..effectively blocking and absorbing. If they added about 20 more sq ft of it to the floorpan and trunk we would have a quieter ride stock..

I forgot to mention that the stock carpet does have a couple chunks of jute underneath it..just not very much at all. There is also an oddly shaped piece of styrofoam on both sides that is wrapped in jute..it lifts the floorpan level..anyone else know what I'm talking about?

bjr

I have finished my stereo install and want to do any sound deadening in stages. Right now I still have interior panels off across the back by the trunk latch and up around the corners to the wheel wells, plus rear and top of strut bar. I would like to decide what to do in this area and get it back together then later attack the "open" part of the trunk in the spare tire area that is accessable without ripping off panels. Then move on to the rest of the car since it will have to be taken apart again anyway.

I basically wanted to know if these panels I mentioned would be best served by carpet padding and what it's absorption properties are vs. using something else thin that would be more effective. Would I want to consider any composite products on the back of these panels? I don't understand if these particular panels need to be padded to prevent vibrations from the sub and provide a little absorption or if you need maximum sound reduction in this area. I've followed everything close so far but noticed you attack the car from the ouside in sort of. By the time you get to some of these interior panels are you looking to gain a lot more noise reduction or just keep it rattle free? Hope this makes sense

dannichols

You don't want to absorb the music you are creating.. you want to absorb and quell the annoying noise from outside the vehicle and coming from the tires on the road. Coating the interior of the car like a recording studio with acoustic foam would be a bad idea..this is why the composites have a barrier on top and an absorber on the bottom.

Someone on here from the sound dampening industry made a great analogy a while back concerning auto and airline noise. Foam earplugs are very effective in reducing interior noise in a jet but only for high frequencies. Low frequencies will pass right through. This is why it's rather difficult to listen to a CD while on a plane unless you crank it up. Low freqs in the 350z are best blocked with a barrier/dampener like extreme matting. mid-Higher freqs can be quelled by a layer of absorbant foam followed by a barrier to trap the noise and cancel it out.


Some of the areas are getting to be a cloudy memory since I did most of this awhile back. But my general suggestion would still be the approach I mentioned before concentrating on dampener topped with absorber topped with barrier. This same approach can be used behind panels if there is enough room. Kick panels, side panels behind seats, and some of the rear side trunk panels can easily accomidate up to an inch or so of this type of material. Others will be very tight and you will have to use best judgement. From my experience, there was very little room between the panels covering the forward portion of the rear wells and the panels covering the strut bar. About the best you can do there is a matting or liquid coating.

1. Liquid Spectrum or B-quiet outer wells.

2. dampen with extreme mat and or liquid, concentrating on areas around subs, other speakers (doors), trunk.

3. Liquid dampen the floor pan and inside cubby area.

4. Absorber/barrier combo floor pan, trunk and inside cubby area. Barrier (neoprene) can be attached to underside of carpet.

5. Foam/jute behind plastic panels concentrating on those that are lowest and closest to inner wheel wells.

Overkill is a great Barrier, but thicker versions are available on Ebay. Rattle pad or acoustic grade open cell foam like Dynamat Dynaliner is a great absorber. Jute is pretty cheap and available in foam or carpet based material.

My suggestion where you have space:

TOP 1/4" Neoprene
1/2" open cell foam or jute
Extreme dampening mat / alum shield
Liquid dampener
BOTTOM base metal