[78 GHOST]

1970 GTO. How much Dynamat do I need to plaster the inside of this puppy?

I'm looking at the Dynamat Extreme bulk pack P/N 10455 which includes 36 square feet of sound deadener.

Off hand, it seems like two boxes of this stuff for 72 square feet would be a good start.

Does anyone know for sure?

Thanks, Matt

[KCTurbo]

That should be plenty. I would work from about midway up the firewall back to the rear seats then go to the trunk and get the pans and sides. Also look and putting some strips on the under side of the package tray. Then some strips on the exterior door panels. And the rear interior quarters. The strips will work well for the doors and interior rear quarters. Cut them 2" to 3" wide and run them the length of the panel.

[markpj23]

This must be a rich-man's thread... that stuff ain't cheap!!

[78 GHOST]

Well, the #10455 package lists for $310 on the Mfgr's website..

..and all over Ebay for around $100 + $35-39 shipping.

It's not gonna make the car faster, just more tolerable to occupants.

[71gp]

Hey guys,
One thing I am considering when I re- carpet my 71 GP: re-use as much of the original carpet (newer, but wrong color) as possible. Cut away from critical fit areas like seat bolts, pedals, upper part of door sills. This would take advantage of the extra layer of jute padding and sound proofing. Am I asking for trouble?

[El Caballo]

This has been discusssed in depth at the Jalopy Journal...

http://www.jalopyjournal.com/forum/s...amat&showall=1

Hope that helped.

[78 GHOST]

El: Thanks for the link, that was very interesting and it was helpful.

Update: I purchased two 36 SF boxes of Dynamat Extreme on EBAY and the total for both boxes with shipping (which was expensive) was just a tad under $250. Forget about list, get it off of EBAY and suck up and pay the shipping, you'll be way better off that way.

When the car was being painted, I had some lizardskin like substance sprayed on the interior of the cabin. I'm applying the Dynamat on the inside of the roof, the entire floor of the cabin, and I should have enough to do the doors and some of the trunk.

Installation is a breeze. All you need is a wall paper seam roller and a razor knife.

I really cannot believe what a difference this stuff is making. I demonstrated the difference to my wife and she was very surprised at how effective this stuff is.

I intend to install the factory sound deadener I bought a long time ago right on top of the Dynamat, then the carpet. This should be a quiet and solid ride by the time I'm done.

Adios, Matt

[Goatster69]

Keep us updated and let us know how much you ended up using and where you used it. Looking to do the same thing soon.

[78 GHOST]

I'm going to use 72 square feet total.

I've installed:

-About midway up the firewall rearward to the rear seat ledge. From the door sill in, and pasted carefully all around the tunnel.

-All through the inside of the roof. I carefully squirted some seam sealer between the support rails and the roof itself to prevent vibration.

*At this point, I've got about (7) 4 square foot pieces left, or 28 square feet. I still have to paste the area under the rear seat, the doors, and the area below the quarter windows.

It looks like I'll probably use (3) for the doors, (2) for the rear seat area, (1) for the quarter area, and (1) for the trunk divider structure. I've gotta think a little on how I want to use my remaining sheets as I really want to get some into the trunk.

I'll let you know tomorrow how it works out. You'll love it, it completely removes the "tinny" sound inherent to our cars.

-Matt

[78 GHOST]

Here's the semi-finished product.

[78 GHOST]

And still more..

Keep in mind I pasted the inside of the door skin and the inner door frame. I also placed some inside the quarter skin outside of the quarter glass.

I pasted the entire floor 100% for thorough noise and heat protection.. I intend to install the stock replacement sound deadener tomorrow and the carpet.

The package tray is crucial as it really "oilcans" badly. The area between the cabin and trunk is actually pretty solid and only needed a few strategically placed pieces.

I used one 4 foot section to dampen the tinny trunk floor.

Overall, I've used 72 square feet of Dynamat Extreme to paste the interior including the inside of the roof (not shown) and hope it helps quiet the interior.

I'm really impressed with the product as I could literally play the drums on parts of the car, and now all you hear is a dull "thunk."

Money well spent in my opinion.

Matt

[Blue '66]

Hi,I have some questions on the placement of the soundeadner.I notice that you only use strips on the front inner doors and a small piece inside the back window.I am wonering why?I am trying to learn,I will be doing this in the near future.Thanks for the pics!

[78 GHOST]

Blue: Even with the quantity I purchased you've gotta budget how much you use and where. The areas that are hardest to service got pretty much 100% coverage.

I had to stretch the material to get all the places I wanted to cover.. thus the strips in the trunk, etc. I did not want to cover any threaded holes or fasteners in the door and this is why I didn't just put a sheet over the inner door frame. Besides which, unless you have a source of noise you don't need a 100% barrier.

I'm not a NVH engineer, so my approach may be totally off. I'll share with you the things I'm thinking about when I install the deadener:

-Heat requires a barrier to insulate the heat. Ordinarily I think 100% coverage is best.

-Sources of noise also require 100% coverage to obtain the best noise attenuation. Loud mufflers are a source, and 100% coverage will permit the best results.

-Vibration can be dampened by less than 100% coverage with strategic placement of the dampening material. Think about a drum, the drum creates noise by vibrating and moving air. A car isn't much different than a drum in the fact that vibrations will cause resonance of a body panel. While 100% coverage will eliminate any doubt of vibrations, examining which panels are prone to vibrating will reveal where you can place a piece of deadener to get the best results. You can silence a drum merely by placing one finger on the surface of the drum, you don't need to put your whole hand on the drum.. same principle. On a lot of large panels which tended to "oilcan" I merely placed a piece right in the middle, just like a finger on the drum.

You'll notice the area between the trunk and below the rear seat back didn't get much deadener.. this is because the metal is very rigid and not prone to vibrations. Conversely, the package tray area got pasted really well because it IS prone to vibrations. I use a really complicated and scientific method of determining where and how much deadener to use.. I thump it with my finger

I have yet to run the car, but I've noticed a big difference just working inside the car. I assume when I get the stock deadener and the carpet installed things will be much better than before.

While I used 72 square feet, I think 100 square feet would give you enough to paste the entire roof, doors, floor, firewall, and trunk.

Good luck on your project, Matt

[FSJplumcrazy]

Matt that's a good write-up with plenty of pictures for the illiterate (like me).
Thanks for the heads up on the da'Bay...makes it a little nicer on the pocketbook.

I used industrial "rhinoliner" on the floor of the convertible as well as the trunk area, but I'm still going to use the Dynomat under the carpet to block out engine/road noise if possible. I don't have the same "tin can" effect that a hard top does, but I'm using your scientific method to see where I need to block vibrations.

Keep us updated on results
Wayne S

[Blue '66]

Thanks for the ideas!Did you put any behind the back seat under the pkg tray?I have fatmat that a bought several months ago.It was cheaper,I forgot how much I got.

[78 GHOST]

Blue: I pasted the top of the package tray, you can see what I did on the very last picture.

I suspect this is probably one of the worst places for vibrations. I used to be able to play a tune on the package tray, now it's just a dull thump.

Take care, Matt

[dean7276]

78 Ghost,
so what's the final verdict? how is it compared to before?

[71Formula]

I used this stuff. http://www.raamaudio.com/cgi-bin/index.cgi?p=pr

Works excellent and is way cheaper. One roll covers 62 sq ft and was enough to do my floor, rear quarters, behind the seat and some of the package tray area in my '71 bird. I need a little more to do the doors (trying to buy some scraps from them). I plan to use Second Skin Spectrum Sludge on the trunk floor to keep it more original looking.

The trunk floor in my car is probably the biggest contributor of the noise in my car. So don't over look it.

[dean7276]

Originally Posted by 71Formula

I used this stuff. http://www.raamaudio.com/cgi-bin/index.cgi?p=pr

Works excellent and is way cheaper. One roll covers 62 sq ft and was enough to do my floor, rear quarters, behind the seat and some of the package tray area in my '71 bird. I need a little more to do the doors (trying to buy some scraps from them). I plan to use Second Skin Spectrum Sludge on the trunk floor to keep it more original looking.

The trunk floor in my car is probably the biggest contributor of the noise in my car. So don't over look it.

that stuff looks good.ill be giving them a call when the time comes.

[78 GHOST]

Dean, I haven't been able to take a road test. However, starting the car in the garage and running it while inside is substantially quieter.

I'm working several different projects on this at the same time, so hopefully everything comes together soon and I can render the final verdict. For now, I'd say anything you do to dampen and absorb sound is a good move.

I'm running a Rhino liner on bare metal, then the Dynamat, then the stock dampening material, then the carpet. I've added a bit of weight, but this car isn't a race car, and the cruising manners are very important.

I'll post when I can, Matt