Going overboard with sound deadener?

[chevynut]

I see guys putting Dynamat or similar over every square inch of the interior of their car. In concept, these sound deadeners are supposed to add a mass layer separated by a flexible layer to deaden vibrations in large panels. I can see how adding the sound deadener to panels that can vibrate, like the inside of the door skin, door interior, inside of the quarters, inside of the roof, etc. but I'm not sure I see the benefit of covering a Nomad b-pillar or even every square inch of the floor. I think if you look at what OEMs are doing you'll see fairly large sheets of sound deadener attached to panels, but not over every square inch, pressed into every nook and cranny of the interior. Inside the roof I think all you need is to cover the majority of the panel, not the braces and every exposed piece of metal. You only need enough to dampen the vibrations of the panel, and I don't see how covering a b-pillar does anything. Sound deadener is like attaching a shock absorber to the panel, not adding insulation. Thermal Insulation is a different thing altogether.

So bottom line is that I think over-doing sound deadener just adds weight and doesn't really accomplish any more sound deadening. And the stuff is pretty heavy.

What do you guys think about this?

[rockytopper R.I.P 5-13-2017]

I covered almost every inch in my cutlass and you still can't hear to talk on the phone when cruising above 70. I even installed the original carpet deadening material over the mat. The exhaust and mainly wind noise is to much. Sense these old cars aren't much on aero the wind is loud cruising at todays highways speeds 75 and above at least my cutlass it is, can't speak to a trifives aero effects yet.

[chevynut]

Rocky, the point I'm trying to make is that you could have covered half or less of your interior and achieved the same level of sound deadening. Adding more doesn't always produce any better results.

Here's an interesting website:

http://www.sounddeadenershowdown.com/

I think adding small panels does every bit as much as covering everything. I put strips of Raammat INSIDE my tailgate between the bars on the outer skin. I think that will help a lot, and plan to do the same inside the quarters and doors. Since I have aluminum side panels fitted tightly to the door and rear inner quarters I will likely not be able to add much, if any, sound deadener under them. I'll probably attach pieces where I can, and maybe even some inside the inner door panels. Even the factory put tar paper on the outer skin of my Nomad's quarters. To me that makes sense, but again I don't think you have to cover every square inch.

[JT56]

My floor is completely done, but on inside my doors, roof and rear seat area i didn't do every inch. I also put bubble wrap in the roof and lined the doors as well. Its relativity cheap and doesn't add much weight. These cars have a lot of windows so it can be challenging to keep them cool. I am pretty happy with mine. Would do it the same way again.

[NickP]

I'm considering "Lizard Skin" for the 57. They have applications for heat and sound. Still investigating.

[chevynut]

I dunno Nick, I never thought too highly of those spray-on sound deadeners. Sure, they will deaden the sound some as would Slicksand, bedliner, or anything else sprayed onto the bare metal. I think they might work better as heat barriers than as sound deadeners.

[Rick_L]

I agree with your thoughts on the Dynamat. You don't need it on braces or on the crease of a bend, any high crown surface. People tend to think of using that as a shield, like bullet proof glass or body armor, and that's simply not the way that Dynamat works. There are two other unrelated reasons not to go overboard with the stuff. One is that's just extra time and expense (and the stuff isn't cheap), and the second is that it adds a bunch of weight.

My intuitive take on Lizard Skin, along with my lone semi-scientific thump test on an actual vehicle, tells me that there's no way Lizard Skin can get it done. There's just not enough of it there when applied as directed. And even if more worked, you couldn't afford it. Sound insulation in general requires mass, just how much can be in a few coats of liquid sprayed on? There's too much resin and solvent, and not enough heavy stuff. As far as Lizard Skin being heat insulation, again there's not enough of what constitutes good thermal insulation.

[Rustaddict]

I have done some reading on insulation and I am still just as lost as a fart in a whirlwind when it comes to what is best.

[chevynut]

Rustaddict, IMO insulation is different than sound deadening. For good insulation you have to have air trapped in small pockets. For sound deadening, you need mass and a layer that absorbs vibration.

[Rustaddict]

I agree. The part I could never decide on is which brand is best. I put heat insulation behind my firewall. I wouldn't mind using some sound deadener on my floor but can't decide which way to go. I'm hesitant to use it in my doors and quarters because it seems like it would hold moisture and I live in a humid environment.

[Bihili]

Lots of Dynamat for sound deadening and then install loud mufflers.
Not trying to steal your thread but I always laugh when guys do this.

[Five Seven]

I will add my experience to this thread hoping it helps others. I spent quite a bit of time reading about what is available in the market etc.... My 57 doesn't have an interior (it will soon, at the shop) so I drove it with a bare metal interior, just a front seat. I will also say that my exhaust is temporary, just pipes to the rear axles with glass packs. Driving the car becomes uncomfortable after 10 minutes due to noise, and I don't mind loud exhaust. I installed materials from sound deadner showdown using their system which includes the tiles, closed cell foam, and MLV. I did 100% of the floor and only 50% of the firewall and I can say there is a marked difference in noise reduction. I then completed the inside door skins, quarters, and installed the back seat and got a next level improvement. The car went from unbearable to being able to drive it 80 miles in one shot. Not a very scientific analysis but hopefully establishes some level of difference. I agree with Chevynut's first post. I think there is a method to the madness with noise reduction.

[rockytopper R.I.P 5-13-2017]

The best sound deadening you can buy is a good stereo, a huge AMP, and powerful speakers. It will eliminate most sound issues and even squeaks and rattles that all these old cars have LOL.

[carls 56 (RIP 11/24/2021)]

if your going to do it, doesn't make sense just to do some (most ) and not all.

[chevynut]

if your going to do it, doesn't make sense just to do some (most ) and not all.

Why not? Some coverage deadens the sound some. In fact, OEMs don't use sound deadener everywhere. Just a few sheets here and there help immensely to keep the panel from vibrating. This material doesn't BLOCK sound, it deadens vibrations of the panel which transmits sounds.

[Rick_L]

This material doesn't BLOCK sound, it deadens vibrations of the panel which transmits sounds.

Actually that IS how you block sound.

[carls 56 (RIP 11/24/2021)]

Why not? Some coverage deadens the sound some. In fact, OEMs don't use sound deadener everywhere. Just a few sheets here and there help immensely to keep the panel from vibrating. This material doesn't BLOCK sound, it deadens vibrations of the panel which transmits sounds.

because you have already gone to all the trouble and cost. what's a few minutes more to not just do it all. common sense in my opinion and pretty lazy no to just do it all. :geek: ............. knew you would have something to say about my opinion when I made it. getting a little old Lazlo.

[chevynut]

because you have already gone to all the trouble and cost. what's a few minutes more to not just do it all. common sense in my opinion and pretty lazy no to just do it all. :geek: ............. knew you would have something to say about my opinion when I made it. getting a little old Lazlo.

You're getting a little old Carl :p. You provided ZERO supporting facts for your "opinion". Why can't you just debate things instead of attacking and getting defensive? All I did is refute your comment with facts. Why are you so offended when anyone asks you a question? Put on your big boy pants. ;)

The fact is you don't need to cover every square inch. It costs a lot and it adds more weight. These materials are heavy and expensive. I saw a picture where someone covered even the b-pillars and the entire interior as if he was painting it on. That's unnecessary.

Rick is right, and maybe I didn't explain it right. What I meant is that the sound deadener material itself doesn't block sound by itself. If a panel doesn't vibrate it doesn't transmit sound. You don't put shock absorbers all over your car, you put them at the suspension points. In the same way, you need to add enough sound barrier to deaden the panel's vibration. If you can do that, the sound won't be transmitted. Most of these sound deadeners are butyl or other type of rubber with a metal film attached to one side. It acts like a spring and a weight to dampen vibration much like a shock absorber. It's not like thermal insulation where you need thickness and air pockets to prevent heat transfer. Anything, even thermal insulation, blocks some sound but you have to stop the vibrations to most effectively block it. This is also why I believe the spray-on sound deadeners aren't worth it.

Read Rick's post #7 above...that's exactly what I'm saying.

If you build a wall out of sound deadener alone, sound can still get through it. It's not like armor or a Faraday cage.

[Five Seven]

My take on this is they are two different issues. I buy into what the sound deadner show down site is trying to put out there. You do not need 100% coverage to reduce panel vibrations. That is what the Tiles do and why there isn't 100% coverage. They also go on to say that you need the closed cell foam to isolate the mass loaded vinyl from the panels. My understanding is that the MLV blocks or perhaps absorbs sound. The question becomes do you need 100% coverage of the MLV? Sound deadner advocates that you want to make sort of a bathtub type enclosure from the window line down. I found that hard to do and so I don't have 100% coverage - not even close. I can say if all I did to quiet down my car was use the tiles, it would be much louder than compared to tiles+CCF+MLV.

[chevynut]

Of course it doesn't "hurt" to cover everything 100%. And it doesn't "hurt to put sound deadener over sound deadener over sound deadener. My point is it's not necessary to reduce noise significantly. Just a little in the right places can do a lot. I don't think you need a "bathtub" enclosure to do this. I think it makes sense to put the foil-type deadener on large areas like some areas of the floor, the firewall, some of the inner quarters, inside the doors, and definitely on the roof where you have large expanses of flat steel to vibrate. Then you need to address the heat from the firewall, floors, and the roof with thermal insulation that will also help block sound some.

I just don't think you need to get carried away with it. I'll bet if you get 50% coverage you've blocked 90+% of the noise that you'd get with 100% coverage. You'll never block it all. Is it worth it to go another 50% in weight and expense to get another 10% reduction? Maybe some audiophiles would say yes, but hotrodders don't need that quiet of a car. I want to hear the engine. ;)