[cv70chall]

Dynamat has always been a good choice for sound deadening and improving acoustics, but Hushmat is actually a better alternative.
www.hushmat.com
The company has a background with OEM manufacturers and offers a full line of different materials, thicknesses and options depending on the level of deadening you want to achieve.
Hushmat panels are 2 square feet and cost $12-$14 each. the nice part is, these are BLACK rather than silver, so they don't stand out and don't have to be painted where they are exposed.
Also, the Hushmat foam works real well under the carpet- on top of a treatment of regular hushmat.
I plan on doing hushmat on the floors halfway up the firewall all the way up the back seat support wall, including the trans tunnel.
After that, a layer of 1/8" Hushmat foam over the floor treatment and you will be amazed at the increased quiet. (Approx. 10-15dB sound drop)
Also treat the package tray, tail panel and trunk lid for added performance.
Hope that helps!

Chuck

[johannes]

Hi guys.
I know there are tonns of info on this subject,...I'm trying to avoid having to read it all...
Both my cars are ragtops, and the one having a 3" exhaust is way noizier than the other "stock" exhaust.
So my question is,.....how much effect will covering the trunk with Dynamat have ?
Any thoughts?
JB

[Adrian Worman]

Hiya J, nice to see you on here
the insulation will kill off any resonance, vibration thru the pipes etc, but it won't muffle the sound of the pipe with the top down, you should want to hear that surely

[cv70chall]

Hi J,

A few suggestions (I work in the high end autosound industry) that will help.

Hushmat (www.hushmat.com) is real good and not too expensive. They offer various treatments.
Dynamat (www.dynamat.com) is also good. Hushmat offers foam deadening panels that are an upgrade.
Lizard Skin (www.lizardskin.com) Applied by sprayer. This is easier to get full body coverage and they offer a ceramic based coating that you can spray their sound deadening coating right on top of.

They all work well- and they all offer different products for specific needs/ situations.
Hope that helps.

[johannes]

.... Thanks for the liks guys....

I took the troubble of performing a quasi scientific experiment....just completed this afternoon.
For your ears only... he he...the audio quality is poor unfortunately..
http://www.youtube.com/watch?v=69KVu3Wq ... e=youtu.be

You can see my friend Otto on a few sceenes.
He is yet to repair his -73 Barracuda after a mishap last summer...tire explosion,..so he is hanging around my garage whilst collecting parts to begin his restoration...A decent grille is needed....


When thinking of it, the focus should be on type (and number) of mufflers used,
and whether H-pipe or X-pipe is installed....
I have 2x2 mufflers but have not installed H-pipe yet....no room for X-pipe with the OD.

The relatively deep rumble from a 3" exhaust is difficult to get rid of....
Perhaps the simples way to get a "sencation" of the difference, is playing deep exhaust noize on an audio system, whilst comparing 82 dB to say 73dB.... perhaps a proffesional audio sale place can assist you ?

Was it worth the work ?,....Well I wanted to throw out the red carpet anyway.
90% of the work was done in the trunk,..so relatively easy to perform.
Also,..my hearing is already damaged,...and I have forgotten how the car used to sound....
There is a lot of salt on the roads, so no real testing for a few months still....
My hope is that I now will enjoy music even more whilst driving....

Thanks; JB

[cv70chall]

The standard Hushmat along with some 1/4" Silencer Megabond foam applied to the length of the tunnel from the top of the firewall to the back of the rear floor will do the trick. I've treated that entire area and treated the floors with Hushmat plus 1/8" megabond on the floors. A good dose of undercoating in the rear wheel wells also reduces the resonant sounds they tend to amplify.

Hope that helps!

[Adrian Worman]

Forget any noise issues....................that Cuda is absolutely gorgeous, lucky boy

[johannes]

The standard Hushmat along with some 1/4" Silencer Megabond foam applied to the length of the tunnel from the top of the firewall to the back of the rear floor will do the trick. I've treated that entire area and treated the floors with Hushmat plus 1/8" megabond on the floors. A good dose of undercoating in the rear wheel wells also reduces the resonant sounds they tend to amplify.

My focus was on the exhaust noize, not the road noize....
Please consider the fact that the only barrier between the trunk and the cupe is the sack for the soft top...
The exhaust is released just aft of the trunk via megaphones.... so I wanted to prevent this noize finding it's way back into the car...
On a hardtop car, one can perhaps insulate the noize using a barrier behind the back seats?

Side note;
Changing from solid rollers to hydraulic rollers (w/new cam) reduced valve noize comming from the engine....and stole 25 HP...(inaccuarncy between HP readings may play a part in this,...but same dyno was used)

[johannes]

Forget any noise issues....................that Cuda is absolutely gorgeous, lucky boy

You're right Adrian.
Plymouth did a good job with the design...and inbetween all the fustration when things are not working,..I sure feel lucky to have this toy.
Trying to limit the negative consequences of my upgrades....a 3" exhaust sure makes more noize than the original.
This fact, and the better luggage space is why we use the Challenger when on hollidays...