Sound Deadener: Dynamat or Second Skin?

[Luke111]

I've used an a-weighted and c-weighted spl meter to test the effectiveness of dynamat-like materials for car audio competition. They are almost completely ineffective at rejecting road noise. You use them to change the resonant frequency of sheet metal.

I spent almost a decade convincing myself the effort was worth it, but Ive conceded that it's mostly a placebo effect.

I've done two trucks and find the noise level on the road to be greatly reduced ..have no idea about how you'd use your meters to test road noise for car audio competitions...they are pretty much parked aren't they?

Here's some good info for the placebo.

http://www.crutchfield.com/S-8AdHWoesuHr/learn/car-stereo-proving-ground-pt-4.html

Lou

 

[SM Racing]

The regular Dynamat is not a sound blocker, it is a vibration damper. Dynamat is the same stuff as the OE "tar" sheets. Notice the OE doesn't cover every single inch, because you really don't need to. Plus you add a bunch of weight for no reason.

I found this thread when I was looking for info on my sound deadening project.
http://www.cumminsforum.com/forum/9...s-consider-when-soundproofing-your-truck.html

For anyone that has owned or been anywhere near a Cummins powered anything you know they are loud, even before you start modifying them. The diesel components are just extremely noisy. The injection pump, injectors, sounds of combustion, etc. That doesn't count the road noise. Dodge did a good job of making those trucks quiet inside, but they are still pretty noisy. The Diesels especially. I am in the process of doing the inside of my truck to see if I can make it even better since I have a long road trip in my tow rig shortly. I didn't add a single sheet of Dynamat, etc. I simply used the carpet pad I listed in my other posts. with no carpet, and no quarter panel skins, you can tell a tremendous difference in how the interior of the truck sounds. I will be installing the carpet and rest of the interior panels shortly. I can't wait to see how it sounds with the rest of the interior in the truck.

Put for the Land Cruiser, I would buy some Dynamat type product and use it in select areas. Once you pull the interior out, start tapping on various sections of the chassis, any section that you hear resonate, ring, or sound "boomy", stick a piece of Dynamat to that panel. You don't need a ton, just about 25% of the area needs to be covered. Just enough to lower the frequency of the vibrations.

The backsides of all the door skins need some. Yes they are bonded to the door bars, but there are still some pretty big areas that are unsupported. They will make some noise. I would add a little to the A and B pillars and there are a couple of box sections in the C-pillar that sounded kinda loud so I stuck some small pieces back there.

For the rest of the truck cover the whole floor with carpet pad, cover the rear wheel wells, the insides of the quarter panels, the tunnel, the passenger kick plates have a bunch of space and they seem to let a bunch of noise through, etc. I am seriously thinking about pulling the door panel off and checking to see how much room I have in between the door panel and inner door skin to put some padding. I don't know that I can get much in there, but its easy to look.

These trucks will never ride like a Lexus luxury car, however, I am extrememly happy with the change in mine. You can tell there is less harshness to the small bumps. Before they seemed to really jolt the chassis and kinda reverberate through the body, they don't anymore. You can also tell a difference in level of road noise. Even with AT type tires that are fairly noisy, there is a considerable drop in road noise. I would like to put a sound meter on my truck and then compare to another one side by side, just to see what the end result is.

 

[nukegoat]

I've done two trucks and find the noise level on the road to be greatly reduced ..have no idea about how you'd use your meters to test road noise for car audio competitions...they are pretty much parked aren't they?

Here's some good info for the placebo.

http://www.crutchfield.com/S-8AdHWoesuHr/learn/car-stereo-proving-ground-pt-4.html

Lou

The meters are portable. I didnt word that well - i meant in the course of doing car audio competitions, I had access to meters and tested my dynamat installs. Always convinced myself it was worth it but the numbers showed virtually no difference.

Closed cell foam, or rockwool, or lead sheets will insulate. But dynamat / raammat / butyl are resonance dampers, not insulation

 

[CA Cruisin]

Brett,
I am curious about your comment, "I am extremely happy with the change in mine. You can tell there is less harshness to the small bumps. Before they seemed to really jolt the chassis and kinda reverberate through the body, they don't anymore. " The Dynamat coverage you applied on various body panels improved the ride quality? How does that work exactly? I'm looking to get mine as smooth as I can....

 

[Billy Skaggs]

like post 18 carpet pad works well but us hair pad instead of the foam. hair pad is the fiber kind like stock fuzzy stuff . for the heat at the center console i use the bubble wrap at lowes . it aluminum foil bubble,foil,bubble,foil 1/4" thick comes in 16",24"48" width 25' long it works great. IT took the floor board heat away for about 30 bucks i layer it under carpet.

 

[thatcabledude]

for the heat at the center console i use the bubble wrap at lowes . it aluminum foil bubble,foil,bubble,foil 1/4" thick comes in 16",24"48" width 25' long it works great. IT took the floor board heat away for about 30 bucks i layer it under carpet.

I did the same thing in my 80. Covered the hump and the front floor pans. Made a difference for sure. I will post pics later.

 

[SM Racing]

Brett,
I am curious about your comment, "I am extremely happy with the change in mine. You can tell there is less harshness to the small bumps. Before they seemed to really jolt the chassis and kinda reverberate through the body, they don't anymore. " The Dynamat coverage you applied on various body panels improved the ride quality? How does that work exactly? I'm looking to get mine as smooth as I can....

Before I started down the road to quiet the truck, I noticed the truck was fairly harsh when it came to small bumps or breaks in the pavement. Take an expansion joint or small broken portion of pavement. When the tire hit the leading edge of the bump, I used to have a strange "reverberation" if you will, through the chassis. Kinda like the chassis was vibrating slightly with the hit. You would never see it on smooth bigger bumps or dips in the road because there wasn't the harsh impact.
Now that I have done the sound deadening the truck is much smoother sounding over those bumps. I haven't changed the suspension or other components to affect the mechanical reaction to the impact, haven't adjusted tire pressure, etc. The truck's reaction to the impact is noticeably less harsh. There isn't the "buzz" through the chassis that I had before.

There is still some road and tire noise, but I am running fairly worn BFG ATs, so they will make some noise anyways. Overall the change in sound levels inside the cab and the noticeable drop in impact harshness has made the work well worth it.

I also covered the tunnel in the aluminum foil bubble wrap to try and cut the heat. I haven't take the truck on a long drive yet so I don't know if the heat level has dropped or not. I can't imagine it wouldn't, but who knows.

I suspect I am going to go back and add some more sound deadening to the doors if I can figure out how to fit it between the door cards and the inner door skin. I suspect that will help cut a lot of the outside noise. The factory door cards ride ride against the metal inner door skin, so I don't know if there is room to fit another 7/16th inch worth of insulation.

 

[Billy Skaggs]

U can us mastic its in lowes,homdepot in ac duct department. its water based so clean up with water . when it drys its water proof and stops vibration. its used for ac duct sealant in homes ac duct work. i know it works for vibration because i used it to stop bass vibration in my cars. and keep the sound in. with big systems . u can brush it on or smear it with hand with a glove on. so were ever u can put hand u can put mastic

 

[Billy Skaggs]

this is 1gl tub

 

[Dazrin]

U can us mastic its in lowes,homdepot in ac duct department. its water based so clean up with water . when it drys its water proof and stops vibration. its used for ac duct sealant in homes ac duct work. i know it works for vibration because i used it to stop bass vibration in my cars. and keep the sound in. with big systems . u can brush it on or smear it with hand with a glove on. so were ever u can put hand u can put mastic

Interesting. How durable has it been when you have used it in vehicles? Not exactly the normal usage for the stuff.

If it really works and even if you need to do 2-3 layers to get up to a comparable thickness you are only talking about $1/SF rather than $2.50-$4/SF.

 

[82much]

Will all these products help with insulating the interior also?

 

[Billy Skaggs]

its in my truck inside doors on outer skin if u look in the truck door behind the support bar the factory uses a similar product in time it gets pretty stiff ive had it in my 1987 toyota van for 10 years and still good you can buy it in pints like 6 buck smear it on something let it dry and check it out.