Dynamat?

[Guest]

Now that my car is due back from the paint shop I'm looking to replace original sound deadening material that was stuck to the insides of the body panels (doors, roof, quarters, floor). It looked like an asphalt based material originally.  I'm looking more for a sound deadener than an insulation. Has anyone here used Dynamat? And if so, are you happy with the results? Would you recommend any other sound deadening material?

[jpage]

Dynamat has it's uses as an insulator but I would only use it on areas that are not exposed to water like  the body sides and inside of the doors are. Reason being is that the door  windows and body trim on those cars are not sealed from water and any edge can collect and hold water. I would recommend something like a heavy spray on undercoating or brush on bed liner material for the doors and body sides so the edges will not build up. Dynamat would be good on the floors and sail panel areas but it can get quite expensive.

[Xander Wildeisen]

I use rattle trap, you can see it on ebay. Or order from the company, works great. I cover the whole inside with it, makes a big difference in sound/insulation. 

[Guest]

Thanks Jim. I know what you mean about price. The Dynamat is pretty expensive.

 

Xander, I'm not familiar with the rattle trap brand. How is the cost?

[Xander Wildeisen]

http://www.fatmat.com/shop/rattletrap-6563

[trimacar]

I used the Dynomat on the inside of doors, 1940 Packard convertible sedan, and it made a huge difference in the way the door closes.  From a tinny sound to a bank vault sound.  I didn't cover the entire skin, just the part one could easily reach while window mechanism is still in car.

 

Yes, it's expensive, but sure does a nice job.  The surface applied to needs to be clean, and make sure you have it positioned where you want it, once it's in place you won't move it....

[auburnseeker]

I see everyone covering the entire floor pans with this type of material and wonder doesn't it somehow trap moisture from sweating?  In effect eventually causing rust/ rot?  Kind of like making a house too tight that it actually can't breath.  Seems those surfaces still need to breath.  Probably not nearly as much a problem with a cherished collectible that is never out in the rain and stored in a heated garage,  but I've even seen very expensive high end builds stored in the most terrible conditions. 

[Paul Dobbin]

I use that bubble pack stuff with aluminum foil on both sides, available at Home Depot. Lowe's and almost any automotive Flea Market.  Installed with spray adhesive on the entire inside of the body and cover its seams with aluminum foil duct tape..  

Weather proofing and sound deadening is very good as well as keeping my passengers cooler in the summer.

[joe_padavano]

There are probably a dozen different vendors of "Dynamat-like" products on the market.  They are all basically the same. They are NOT the same as the bubble wrap product.

 

I deal with launch acoustics for space launch vehicles in my real job. The most effective way to kill acoustic transmission is to throw mass at the surfaces that are being excited.  These Dynamat-like products have multiple layers of foam and high density viscoelastic material that both increases the mass of the panels and deadens the sound.  The multiple layers also help because acoustic transmission changes when density changes and the break between the viscoelastic layer and the foam causes the acoustic waves to be reflected instead of transmitted. The lightweight bubble wrap does none of this.  It might help with thermal problems, but not acoustics.

Dynamat and others now sell a variety of products with specialized purposes such as thermal insulation or whatever.  I have not tried these others. 

 

[HarryLime]

Well.........it really is rocket science .

[Guest]

5 minutes ago, 23hack said:

Well.........it really is rocket science .

[Xander Wildeisen]

Where I live you do not have to worry about moisture getting trapped behind/under anything, we are a high desert here. And if installed correct, do not think in would matter anywhere. You do want to measure/cut and test fit the piece before pealing off the backing paper. Once placed down, it really sticks. I install it on every surface inside, that has an exterior surface on the other side. You can really tell the difference on a car with a product like rattle trap/Dynamat. A must do in the build process, IMO.  

[joe_padavano]

46 minutes ago, Xander Wildeisen said:

 And if installed correct, do not think in would matter anywhere. You do want to measure/cut and test fit the piece before pealing off the backing paper. Once placed down, it really sticks.

 

X2.  This product is routinely used on the backside of door panels with no problems.  Get the small wooden roller to press it down securely.  The biggest problem with using it in doors is often getting the factory applied spray-on dum-dum off, since that surface is usually too rough for the Dynamat to adhere properly.

 

[60FlatTop]

I bought a large roll of 1/16" rubber from a local seal company. Rubber is a real good sound stopper. On a few cars I have made an inner seal under the door panels. It gives a solid thunk to the closure. On my '64 Riviera I sandwiched a 3/8" carpet underlay between two sheets of the rubber to make a new firewall insulator. That worked well. Recently I wrote about making cushion gaskets fot my '60 Electra wheelcover diecast parts. It is handy stuff and I use it mostly as sound deadener.

Bernie

[John_S_in_Penna]

6 hours ago, Xander Wildeisen said:

Where I live you do not have to worry about moisture getting trapped behind/under anything, we are a high desert here. And if installed correct, do not think in would matter anywhere. ...

 

I can't speak about the various products, but I do know

that we're restoring for history, for permanency.

Any car that's high and dry now might, 20 or 40 years from now,

end up in Maine or British Columbia or any other wetter climate.

So I say, plan for all realistic circumstances!

[F&J]

9 hours ago, Paul Dobbin said:

I use that bubble pack stuff with aluminum foil on both sides, available at Home Depot. Lowe's

 

I just used that stuff on the inside of a 1932 firewall with a big Olds V8.  I did not want a tar/type product on the back of a hot firewall.  So far I don't feel firewall heat, on fairly warm days.

 

 

11 hours ago, GregLaR said:

How is the cost?

 

But Home Depot (maybe Lowes also) has a rubberized/asphalt? foil backed product in the roofing supply isle.  It is super sticky, and is a long roll about 8" wide?   It is called "gutter-seal" or something.    That stuff is super on sound deadener to make doors sound like a vault.  Way, Way cheaper than the high roller products mentioned.    I used this stuff on two oldies so far, inside the doors and quarter panels.

 

That narrow width is easier to sneak into the doors, rather than fighting a wider sheet.

.

[Guest]

F&J, that's a good tip. I will check it out.

[joe_padavano]

The rubberized asphalt product is similar to a material used by GM, so there is precedent.  It is also used by hot rodders as a low-buck substitute for a real acoustic barrier layer. Just be aware that while it MAY be an adequate deadener for you, it is not as effective as a multi-layer acoustic barrier.  Also, the asphalt can soften and outgas in the sun.  Your money, your ears and nose, your call.

[mike6024]

I would use it on my roof too if I could afford it, but ordinary felt paper is many times cheaper for that. Bituthene I think was the first of it's type. Many similar products now.

 

http://www.whitecap.com/shop/wc/p/wr-grace-bituthene-3000-36-x-66-membrane-roll-582

 

[mike6024]

There is also this fwiw - http://reoriginals.com/sounddeadeningpanelsforinteriorfloorsdoors-u021052.aspx

Sound deadening panels: for interior floors, doors... - U02105/2

Sound deadening panels: for interior floors, doors & transmission tunnel, aggressive self-stick backing, 40 X 20, 1mm thick, cuts with scissors, use in conjunction with 12-14mm jute mat on transmission tunnel, old style, made in Italy, call for free sample. $42

[Janousek]

I also use Rattle Trap.  Reasonable cost for a good product.  I use the extreme version and double up firewalls and floors.  It really solid when doubled up.   I use it on ceilings and doors also.  Everything I do is blasted/epoxy primed so it's sealed and theirs no worry that moisture could cause a problem.   I also can't see what problems water would do to the stuff inside a door.  Maybe tarnish the aluminum layer?  It's pure rubber based and water wouldn't soak in like the original asphalt soaked fiber that factories used.  

 

I wouldn't ever try to save a buck and use roofing products.  First hand experience from the mid 90's.  Dynamat was coming on strong back then and it was expensive.  I used the sticky sided roofing product for eves and valleys inside my 92' Blazer.  I gutted the interior, installed the mat, installed the interior.  Within a week I had to regut the interior and remove the roofing product due to asphalt smell.  It would burn my eyes on a sunny day.  

 

You can get the rattle trap without logos also.  I did a 59' Cadillac limo with it doubled up and it's a solid car.  I wouldn't build a car to be driven without the stuff.  

[Janousek]

I forgot but another expensive option is Lizard Skin that is a ceramic sprayed on insulation and a seperate sound control spray on.  I like the ceramic spray on firewalls but I like the rattle trap more for sound control.  The spray sound control is pretty thin and doesn't have the same thud when you slap the panel.   The ceramic spray insulation is fantastic for a roof on a black car.  Really blocks the heat.  

 

Years ago I built an outdoor style woodstove that heats water.  I sprayed the entire outside with lizard skin.  The door to the stove is two layers of 3/8" plate with an 3" air gap between them.  No water passes through it so It gets hot but I can touch anywhere on the door without discomfort.  It's warm to the touch but not hot.   The water jacket has 170 degree water in it and it's just warm to the touch also.  

[auburnseeker]

We probably won't know for another 20 years what adverse affects (as far as rust is concerned) any of these may cause.  Just like we found out with the original asphalt sheets and undercoating.   A rust free desert car will probably be just that,  and a damp northeast car will end up the same way we find them now.   It all boils down to storage and use I imagine.

I'm usually turned off by cars with the carpet all glued down, heavily undercoated or in this case if it was heavily dynmatted or similar.  Of course if the car was the caliber of Xander's as you can see from the rest of the work,  I wouldn't be suspicious.  I see alot of cars on Craigslist partially done with all new dynamatt on the  floors.  I immediately think they are trying to hide rusty or poorly patched floors.  (you have to think this way when you live in the North East) 

[Xander Wildeisen]

Shots of a 1959 Chevrolet Truck that had the same treatment. A must do on any build/restoration.

[auburnseeker]

I would be more in favor if it was a matt that could be removed easily.   Especially on floor panels.  Probably years from now,  the new generation of restorers will be cursing us for putting that stuff down.   

I do understand it's benefits.  Just always worried about rust  After  working on stuff coming from the North East. 

Edited April 19, 2017 by auburnseeker (see edit history)

[Xander Wildeisen]

If the factory would of had the product, they would of put it in, and bragged about the "comfort quite sound control" that they invented. Would you build seats like they used to, knowing that mice will make nests out of them in the future?

[auburnseeker]

You would need to live in the North East to really appreciate the type of cars and opinions I have formulated after seeing them around here.  I wish we all lived in a nice dry climate.  I just see rust problems and it being used more like a band aid around here than the way you use it.  As I said in a vehicle the caliber of yours there wouldn't be suspect of it's use,  but around here I can only imagine the number of cars it's been used like undercoating to hide problems.  Solid around here means won't fall apart before you get it home.  Solid in dry areas means no rot usually.  It's just a whole different car world around here. 

Could be akin to the West System on wooden boats.  Seal that wood all up good so it can't breath. Once it starts to fail,  watch out.  that's when they take a saw and cut the whole bottom off the boat , then start over.  I fixed one of those boats built by a reputable shop.  I shook my head when after 10 years it needed a whole new bottom when a Chris Craft with an 80 year old bottom was still in good shape.  Breathability is a necessity in some climates.   Especially ours.  We'll see in 30 - 40 years if there are any problems.  It's no different than the building industry.  I'm always cautious of new products.  The best thing since sliced bread sometimes ends up on the day old rack sooner than expected. 

Beautiful work on your truck by the way.

 Come out East when you get a chance.  You'll just laugh when you see the crap and degree of creep rot we have around here. 

[Guest]

I think I am going to ahead and use the Dynamat for my doors, quarter areas and roof. And, while my floor is very solid and completely rust free, I don't think I'll use it there. Maybe a removable jute backed mat of some kind. Jute backed firewall mats are readily available on eBay with the correct cut outs.

Thanks for all of your input!

[mike6024]

Don't use the mat anywhere water could collect. For instance when putting it inside the door don't extend all the way to the bottom area where water could puddle. Stop short of that. Bottom parts of doors rust out because water doesn't drain out well enough. I could show pictures of that for proof if anyone is interested.

[Janousek]

AuburnSeeker,  I think your worrying about something that isn't going to happen.   Especially if the metal is properly sealed with epoxy primer first.  We don't want metal to breath like a wooden boat needs.  

I just thought about my current truck that I did the floors with back in 06'.  The truck is a 04' Silverado reg cab that I bought rolled over.  I had the interior gutted during the cab repair and used the rattle trap on the floors, ceilings, door panels.  This was back in 06', the truck is in michigan, gets washed a few times a year,  sits outside year around.  I know winter junk from my boots runs down into the floor boards on this truck as I don't have fancy floor mats.  I had to pull the rubber floor mat last year to replace the shifter cable and it was clean underneath.  If my floorboards can last through 10 years of this than an antique car with the stuff is going to be permanent.  

[trimacar]

I think the key in the above post is "epoxy primer first".  If you put Dynomat or a similar product over regular paint, it's very easy to have a gap appear between paint and metal, as the adhesive bond from mat to paint is stronger than paint to metal.

 

I've used DP-90, and on clean metal the bond is such that you can't scrape off the primer, it really bonds to the metal.

 

On doors, you don't need to cover the entire surface, as long as you do about 2/3 of the door skin, the change in how the door feels and sounds will be apparent.

[F&J]

11 minutes ago, trimacar said:

On doors, you don't need to cover the entire surface,

 

I have read that quite a few times.  A piece in the center of a panel is what will change the door completely. I also read the same info on a upscale car radio site.

 

They said the "center mass" will absorb outside noises, and also dampen any resonant vibration caused by noise, like from the door panel speakers they were installing on that website.

 

.

 

 

[Matt Harwood]

https://www.sounddeadenershowdown.com/

[Guest]

I live in Palm Springs, California. Average yearly rainfall 5.8 inches. It rains less than 10 days per year. I don't think rust will be an issue for me. 

[auburnseeker]

The rain is almost less of a problem than the Condensation developed in storage on some cars.  I looked at a 39 Buick Convertible that was covered with dust.  When I touched the car as the non dusty parts looked cloudy,  it was water running off it.  It was one of those hot humid days when everything sweats.  In a garage with minimal airflow,  it doesn't dry none to fast either.  Especially when the water is trapped in all that dust/ dirt. 

[60FlatTop]

I quit washing my cars with a hose and water about 10 years ago. Too many nooks and crannies. I go through some spray detailer.

 

And the girls don't giggle quite as much when a bunch of us get togehter for cleaning day.

 

But their hair stays dry and we manage. Wait! That's not detailer!.... No! Not the chrome polish! Hey, put the Westley's down!

Bernie

Edited April 22, 2017 by 60FlatTop (see edit history)

[auburnseeker]

Just got back from a parts bust buying spree where I couldn't buy any parts.  The building the cars were in was terrible and the any part contacting the floor was heavily rusted.  Even the bran new parts.  They were dragging the cars out of the barn with all 4 wheels locked up.  That's the ones inside on the cement and by the look of the deep ruts on the dirt floor section,  they didn't roll either. 

You have to love the damp Northeast.  Maybe this is where they stored Ms. Belvedere? 

[zipdang]

Novice question here. My '59 Fiat Granluce body is done and ready for reassembly. I've been reading this discussion and am considering putting something like the dynamat or rattlestop on the floor, firewall, doors, top, etc. Originally, this car had the jute carpet padding stuck on something like a tar-based layer that was in turn glued to the floor. This was a mess getting out but had to go in order to the get the body and floor stripped. I see that these new products are quite thin; therefore, I'm assuming they aren't meant as a replacement for carpet padding but just as an underlayment of sorts. Correct? This means that when interior time arrives, carpet and padding would go in on top of this?

[JACK M]

Yup.

[zipdang]

Short and sweet answer. Thanks Jack M.