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I'm not sure about others, but I am very happy with my sound deadening project. I installed some super thick off-brand dynamat material in 2009 along with some 1/4 inch closed-cell foam over the whole floor, including the spare tire well and firewall. I stuffed some polyfill into the rear speaker area and installed rear speakers. I didn't do anything to the doors, but I sprayed expanding foam into the hollow pillars. The windshield pillars made a huge difference in wind noise. I also installed a microfiber material in place of the standard headliner. Finally, I installed a subwoofer under the passenger seat to fill in the sound I do want and help combat remaining road drone.

This was mostly done 8 years ago (sub added 3 years ago) and I noticed immediately that the car was quieter. My wife and I take the car on 5000+ mile road trips every year and take turns reading to each other and listening to music, and the car is a perfect little capsule for that. As a side benefit, the carpets feel super plush now. :)

It was probably about 40 lbs of material overall I added to the car, not counting the sub, but I would have done things a little differently:

- Measure dB before and after
- undercarriage anti-resonant spray as step one in wheel wells, under spare tire, and under passenger floor
- More strategically apply dynamat to reduce vibration rather than 100% coverage (knock, knock, knock, stick, and repeat)
- Thinner closed-cell foam along edges where interior clips are installed
- Thicker & stretchier headliner fabric with open-cell foam backing
- Drill out and pre-run conduit in a-pillars for wiring before filling with foam
- Replace OEM speakers with aftermarket components for clearer sound throughout volume range

Yeah, we added weight to the car. When we road trip the car's over max weight anyway, so i wasn't too worried. I still get well over 70mpg in the winter here in Houston and barely 70 in the summer on the crappy gas and especially with the AC cycling.

They say YMMV, but our cars have so little soundproofing from the factory, I think adding some can help a lot. You will notice a hit in MPG obviously with the added weight, but everything in life is a tradeoff.
 

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lach - that's very interesting. Can you tell us more about the expanding foam in the pillars?
 

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I wish I would have taken pictures as I went along... but i snapped the garnish off this morning and snapped a shot at a traffic light. I basically just removed the garnish, pulled the wires back, stuck the straw of an expanding foam can in there, and let fly. I tried to fill as much space as I could with the straw all the way into the pillar in each direction, eventually filling back to the hole. There was enough expansion that it erupted a bit out of the hole and I had to clean it up afterwards. After that I cleaned the holes back out with a drill bit and an x-acto knife, and popped the garnish back on.



The name of the game in sound deadening as I understand it is twofold: to absorb, and to reduce resonance. The expanding foam did both: the foam in there made sure the pillars weren't resonating chambers for wind (primarily) noise, and also absorbed the wind noise that was going to be there no matter what. Ideally I would have had access to the inside of the pillar and installed baffles and open-celled foam for a lighter application that did a better job, but this was an easy 15 minute job that did a lot of good.

Just repeat this in other inaccessible hollow spaces, and you're golden.

In steel cars there's some concern about trapping moisture and interfering with drainage and stuff, but I figure the aluminum will outlast the foam in this application anyway.
 

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I'm no expert but IMO, lachs post is what folks need to reference and understand when it comes to sound deadening and vibration dampening.

I read this entire thread before commenting and as expected it seems (for good reason) that some folks dont understand that "vibration dampening" and "sound deadening" are two different things that require two different products.

Generally speaking - Dynamat is not a sound deadening material, neither is peel and stick - those are vibration dampening products.

Closed cell foam is a sound deadening product - Ex. OverKill? Closed Cell Foam 9 sq. ft - 24" x 54" CCF - Second Skin Audio

Just my .02 anyway :)

And as lach also mentioned, you DO NOT have to 100% cover with any vibration dampening material, its a waste of money and time. One 1" square can absorb vibration from a much larger area - like 1 sq ft for example

You do however need to cover 100% with a sound deadening material....
Thats why in a previous post, covering the entire rear hatch area with the movers blanket made such a noticeable difference.....

I'm not sure about others, but I am very happy with my sound deadening project. I installed some super thick off-brand dynamat material in 2009 along with some 1/4 inch closed-cell foam over the whole floor, including the spare tire well and firewall. I stuffed some polyfill into the rear speaker area and installed rear speakers. I didn't do anything to the doors, but I sprayed expanding foam into the hollow pillars. The windshield pillars made a huge difference in wind noise. I also installed a microfiber material in place of the standard headliner. Finally, I installed a subwoofer under the passenger seat to fill in the sound I do want and help combat remaining road drone.

This was mostly done 8 years ago (sub added 3 years ago) and I noticed immediately that the car was quieter. My wife and I take the car on 5000+ mile road trips every year and take turns reading to each other and listening to music, and the car is a perfect little capsule for that. As a side benefit, the carpets feel super plush now. :)

It was probably about 40 lbs of material overall I added to the car, not counting the sub, but I would have done things a little differently:

- Measure dB before and after
- undercarriage anti-resonant spray as step one in wheel wells, under spare tire, and under passenger floor
- More strategically apply dynamat to reduce vibration rather than 100% coverage (knock, knock, knock, stick, and repeat)
- Thinner closed-cell foam along edges where interior clips are installed
- Thicker & stretchier headliner fabric with open-cell foam backing
- Drill out and pre-run conduit in a-pillars for wiring before filling with foam
- Replace OEM speakers with aftermarket components for clearer sound throughout volume range

Yeah, we added weight to the car. When we road trip the car's over max weight anyway, so i wasn't too worried. I still get well over 70mpg in the winter here in Houston and barely 70 in the summer on the crappy gas and especially with the AC cycling.

They say YMMV, but our cars have so little soundproofing from the factory, I think adding some can help a lot. You will notice a hit in MPG obviously with the added weight, but everything in life is a tradeoff.
 

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I've got the aluminum sheet off from behind the seats, the piece that rear speakers can be attached. My question : is self-expanding foam a good product to reduce noise by filling both cavities (left and right) behind this barrier and below the rear cover . Lots of room and access to the rear wheel well area. If so, is the type that expands the most or the least best?
 

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Spray away, my friend, spray away.

Please take video so we can all see.

My vote is for triple expanding foam.

Scott
 

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My question: is self-expanding foam a good product to reduce noise by filling both cavities (left and right) behind this barrier and below the rear cover....
I won't say my subconscious is tapped into the library of universal truths, but I had a dream last night, a nightmare, really, about that stuff (and pink fiberglass insulation, and mud)... I was trapped in it.

So, just in case, let me ask, Isn't that stuff pretty flammable and kind of on the toxic side? Like if it burns it melts and spews noxious fumes, if not actually throwing flames? Also, it'd be a real pain if you ever wanted to remove it...

Seems like one might be better off lightly stuffing some Roxul 'Safe n' Sound' or similar back there, in there... I can't see the spray foams, or at least the ones I've seen cured, actually doing much in terms of absorbing sound energy; they cure with a hard-ish, non-porous shell. Seems like a lot of sound energy would just bounce off the surfaces rather than being absorbed and dissipated...
 
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