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Sound Noise Heat Insulation (Dynamat, Brown Bread, ect.)


Guest Anonymous

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Guest Anonymous

I hope I can get some feedback on this subject!

 

I hope I am doing the right thing here.... I found a product that is an asphalt based compound with an aluminum backing like "Peel and Seal". I am applying this stuff on the floor, inside doors, inside rear tail, and on the transmission tunnel. This stuff comes in a 6" x 16' roll, about 1/16" thick, and weighs about 4 ounces a square foot. Sticks very well to anything once heated with a heat gun. I am careful to leave the floor plugs exposed. (I did remove each plug and apply a bit of fresh sealant to each plug)

 

Am I getting carried away by putting this stuff on all surfaces that would be covered by carpet anyway?

 

The commercial stuff like Dynamat is sold in approx 16" x 16" squares, is one of those enough in a door to make a reckonizable noise reduction difference?

 

Will this stuff be better or worse so far as the factory stuff when it comes to harbouring moisture?

 

Some of you guys have had stuff like this in your cars for longer than a year now (according to previous posts), have you dared to check for any rust problems?

 

Thank you for your interest!

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  • 2 weeks later...
Guest cowboy6280

I dont really have an answer but have the same concerns... I have a newly aquired '77 project and was wondering what I was going to use. The idea I had was to have the areas coated with bedliner spray. Not sure if this is going to do much as far as noise but should seal everything up good to prevent moisture damage/rust starting.

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I found out that there are two types of noise insulators. There are the ones that reduce vibration by adding mass. Basically, its just Dynamat that does it this way. The other types do it differently and are extremely light weight in comparison, plus they will noticably reduce road noise. I guess they absorb sound rather than mass load the panel. Check http://www.b-quiet.com/ for a little more info.

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Guest Anonymous

I used Herculiner in my Jeep. I followed the instructions to the letter. I was sure that it would hold up for the duration. Unfortunaley, after one year, the stuff did start to peel away from the floor under the driver's "feet". You know the area around the gas pedal, clutch and brake. I believe that the failure was due to water eeking it's way between the Herculiner and the sheet metal.

The water, in this case found a path in between the layeres at a drain hole in the floor pan.

 

To fix this. I peeled away the Herculiner that was loose. Cleaned the floor pan as directed by Herculiner, and painted it again with Herculiner.

 

Anyway the point of this story is, that even with Bedliner products, if a failure occurs, it may remain unnoticed for some time. Perhaps enough time for a rust through to occur. I think all of this stuff needs period inspection and maintenance.

 

I am still fearful of installing any of the foil wrapped stuff and adhering it to the floor. It would be a real pain to remove it to inspect the floor pans.

 

After searching thru alot of posts about this stuff, I believe that there are alot of Z cars that have had the stuff installed some time ago. I still wonder if anyone who has put it in, has dared to take a look at it and see how the floor pans are holding up.

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Guest Zachb55

i know the tar coatings that were in my car, that were somewhat stock (some obviously not) didnt do the trick, i think the stock tar did an ok job in the hjatch and the drivers side under the legs (did really poorly under both seats and feet areas) and then where there had been metal replace in the foot "pad" was a tar-like product which was either put ontop of rust or just allowed it to grow cause there was rust there too... what im going to do is probably something like a carpet padding covering. then with carpet over that. i want to keep it very light but i also want comfort, as in not noisy as heck... im still not sure on what im going to do. i would maybne be concerned about the stuff that would seal on but if you maybe bought some extra and peeled up a piece every year or so then replaced it you would probably have no problems, if you go for it let me know how it works out, maybe ill look into it as well.

 

-Zach

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Guest Zachb55

oh by the way, thinking of insulation, does anyone remember how many square feet it took to do their car, like the floorboards, tranny tunnel, firewall, kickboard area, deck wall thingy, and hatch area? maybe subtract the wheel wells from that and that would really help me out, thanks, :-D

-zach

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Guest Anonymous

I'm not sure what they are using these days for underseal (undercoat) but I once used the heavy thick stuff (applied with a putty knife 1/16-1/8 thick) and it definitly did the job.

 

Sound can be handled two ways here: The sound hits a car panel and the panel vibrates in sympathy with the fundimental and the subsequent harmonic vibrations, even to the fourth power as far as our ears are concerned. Any panel has a fundamental frequency wave of vibration, then 1/4 length wave, 1/2 wave, 3/4 wave also. As the wavelength shortens the audible frequency heard will rise in tone but the loudest will always be the fundimental (if such is presented to the panel). What this all means is that every individual panel in the car has four chances to vibrate in unison with the various sounds around it. Nice huh?

 

In my practiced opinion you can't beat a deadening weight on a panel to stop it's multiple vibrations. By "Deadening Weight" I mean a relatively heavy mass covering at least the entire central area of a panel excepting four inches inward from the outer edges (where the panel meets a fold).

 

This light weight stuff I am reading about is not a heavy weight that will actuall dampen the vibration at all but only a sound absorbing material that works against the vibrating sound waves as they leave the panel and head twoard your ears. Conversely, heavy materials, as suggested, actually stop all these vibrations at the source (any remaining vibrations are above your hearing range or too weak to be noticed) and there is nothing left to hear at all!

 

Bottom line? Light materials act as 'mufflers' to quiet the sound of the vibrating panel and can continue "Around" the source and still reach your ears. Heavy materials act as a 'damper' (deadener) to effectively 'kill' the sound source and there is no sound left to reach your ears!

 

If you want to silence these vibrations as much as possible while you're at it, get wise and load those panels! If you are so worried about weight, it's your choice and I rest my case.

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