How to: Sound proof, Dynamat / insulation interior

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74Bacon
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How to: Sound proof, Dynamat / insulation interior

postby 74Bacon » 10/10/13 @ 22:07

Ingredients:
(1) pc NA Miata. Preferably a 1991 Super Badass Silverstone Metallic Non-Special Edition
(15) sheets Dynamat Extreme (approx. 28 lbs and $180)
(50) sq. ft. 3M Thinsulate TAI-3027 Sound Absorber (weightless and $100)
(1) huge fucking bale of Roxul Safe'n Sound Mineral Wool Sound Insulation (2 lbs and $45)
Total time required: 20 minutes

The problem:
Supercharged 1.6 + Borla Dual Sport + one outlet tip hidden under valence to look like a single = difficulty hearing or speaking at highway speed

Proposed solution:
Add some sound deadening to the rear of the car to restore hearing inside without being a pussy and swapping to a quieter muffler setup

Step 1: Remove inside of Miata. This requires removal of 2 screws and takes about 10 min

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Step 2: Take Dynamat out of box. CAUTION: Before using or talking about using Dynamat with your friends or posting about it on-line, understand up front that Dynamat and other mass loading products like it are intended primarily to reduce vibration and resonances of the sheet metal panels in your car, while offering a little bit of sound insulation properties. It only requires about 30 to 40 percent coverage to do this for normal people. (People entering sound competitions will cover 100%, add sound absorbers and use Dynatape to tape up all exposed seams and frankly, this thread is not going "full gay" in terms of sound deadening.)

meow that you understand what Dynamat does and does not do, cut it into pieces with scissors and stick it on your car. Most people apply Dynamat to the inside of the car, and leave the outside alone. Use a little wooden hand roller (not shown) to adhere it to the surface of your car.

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last edited by 74Bacon on 10/10/13 @ 22:47, edited 2 times in total.
74Bacon
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Re: How to: Sound proof, Dynamat / insulation interior

postby 74Bacon » 10/10/13 @ 22:24

When applying to the parcel shelf area, don't be a wuss. Take the time to remove the fuel pump cover, the cover over the filler hose, and the big sheetmetal cover that some dumb fucker is always trying to mount subwoofers in another thread. Apply the Dynamat to these covers to deaden them, and to the hidden areas of the rear parcel shelf area

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Notice that when you took the big cover off it revealed what the Dungeons and Dragons enthusiasts in the Miata world refer to as "the tunnels". And no, they are not a place to smoke weed, cross campus, play the game in 1:1 scale, or hide dead bodies. They are just a couple gaps on either side of the gas tank hump that are open air, and channel any sounds from the trunk cavity into the passenger compartment. They represent a gaping hole, and just like phillyb™, your first urge should be to plug that hole.

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You will do this using the convenient travel size Roxul available at Home Depot. It's 46 bucks, but if you are on your game you should be able to shoplift it without much problem

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At this point you are probably thinking, "Holy shit, a whole bale of insulation? $46 bucks just to get a handful of mineral wool that's mouseproof, doesn't hold water, doesn't burn or rot, and is excellent soundproofing material?" and the answer is Yes. You wasted over $60 on your last ticket, you got screwed the first AND the second time you signed a cell phone contract on call, data, roaming and messaging fees, you can't remember what happened during your last $80 drinking binge on the town and the insurance on your 22 year old shitbox Miata costs you far more that that a month. Considering how much money you have spent in your life and have absolutely nothing to show for it this 46 bucks is nothing.

I'll bet you can guess where the Roxul goes:

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If you have enough left over after plugging the tunnels, run a piece in the gap in front of the gas tank area to plug that as well.

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74Bacon
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Re: How to: Sound proof, Dynamat / insulation interior

postby 74Bacon » 10/10/13 @ 22:41

Slap the Dynamatted covers on, and its looking good

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meow get the 3M Thinsulate Sound Absorber. You've probably never seen this stuff in a Miata, can't find a supplier and would rather spend the money on a decent bar night, so here's what it looks like. It's got the smooth, babyskin Thinsulate side like house wrap and the other side is poofy and wonderful.

I don't have cats any more, but if I did I'm willing to bet this stuff is a cat magnet. They'd be crawling all over it and purring in it and doing that shit where they stand there and stomp their little paws slowly up and down trying to soften up their bed before they turn around about three times and lie down in it to take a nap and purr themselves to sleep. Or maybe not

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Use your car for a cutting board using a construction knife. Be sure to push really hard when cutting to get a clean edge the first time

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Cut to shape and stick it in there. Make cutouts for the carpet push fasteners or you will go bananas trying to put your carpet back in. No adhesive is necessary because the carpets will hold it in place

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After that, it's time to fit the carpets.

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For the inside, don't just put the same old shit back in. Get something really rare and unobtainable, for example, the last spare brand new OEM 1993 LE red carpets on the planet. Pay huge money for them and have them shipped in a refridgerator size box from Germany. Stick them in, but not before cutting holes in them for your roll bar (bonus points for cutting them for something really worthless like a style bar)

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You may need to trim back some of the Thinsulate from intersections to prevent it from double overlapping to get your carpets to set right. I'm not saying that's what happened to me, I'm just saying that I have a couple of friends who heard that from something they read on the internet. Yeh.

Step 3: Reinstall the interior.
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phillyb™
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Re: How to: Sound proof, Dynamat / insulation interior

postby phillyb™ » 10/11/13 @ 10:19

nice write up my man!
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74Bacon
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Re: How to: Sound proof, Dynamat / insulation interior

postby 74Bacon » 10/11/13 @ 15:34

Thanks. I have some Roxul left over
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Arjay
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Re: How to: Sound proof, Dynamat / insulation interior

postby Arjay » 10/17/13 @ 04:07

Nice write up. How noticeable is the noise reduction from this? I'll have the dash outta my car soon and might do this then. I'm getting tired of all the rattles and having to yell on the highway. I wonder if there's a way to do a hardtop without it looking horrible.
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Teejay187
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Re: How to: Sound proof, Dynamat / insulation interior

postby Teejay187 » 12/15/13 @ 19:20

This guide is really great, and it is actually generating traffic on the forum! I will make use of this guide when mounting my new stereo.
99' Miata

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