Cabin Rear Wall Sound Deadening Material

I have dynamite in my doors primary for the speakers. However with the top up the deadening is apparent and doors sound more substantial. It is a glue material, check their website

You could try Lizard Skin.  It's a spray on product and you would have enough to do the dead space between the firewall and you could also do the inside of the doors.

http://www.lizardskin.com

I used a thin anti-fatigue mat material from McMaster/Carr in the manner you are considering. It's weatherproof, and I used 3M adhesive on it. The difficulty is getting the surface to be perfectly clean all the way up to where the "tub" joins the firewall.

It made a huge difference. Good luck.

I used something similar - 3/8" thick shop floor mat for in front of the bench.  tapered the edge as it approaches the lip of the tub and cowl just so it wouldn't have a step transition and be noticeable.  

I also used it pretty much everywhere else, too - inside of the doors, under the carpet, anywhere I could fit it in.  Cheap, too, and comes in a 4' or 5' wide roll at Home Depot.

I used a paint on sound deadening material.

I'm thinking of using a spray foam product I saw recently billed as for use in landscaping.  Is a black expanding foam/adhesive.  Thinking of spraying this to exterior of the back "tub".  Then follow that up with some spray-on truck bed liner.  Both products designed to be waterproof, they say. Basic rattle-can deal here.  Also, one key to soundproofing is to provide layers that have vastly different acoustical properties, i.e., sound transmission characteristics, back-to-back.  The foam will be very light and sorta thick, the bed-liner very heavy and sorta thin.  What do you all think of a thing like that?  The Lizzard skin I looked at and came away thinking: expensive, and hard to do, esp'y in your own garage.  Need professional spray eqt.  Best shot would be to coerce a shop that does truck liners to rig up and use the stuff.  Ugh, and many $$.

I've used this materiel from Eastwood and found it works quite well though I have only used it on the hood of an American car:

http://www.eastwood.com/x-mat-...liner-51x39x1-4.html

Not to expensive round $40 for per sheet, the biggest thing when applying is the surface needs/has to be perfectly clean or though it may initially stick it will loosen over time...learned that the hard way. It really holds up under heat and does a great job in sound deadening.

I'm also a fan of Lizard Skin and Dynamat, Lizard Skin, though a p.i.a. to install, works well in high heat areas more so than regular Dynamat though Dynamat does make an underhood product, yet I have never used it so can't speak first hand about it.

Kelly:  That is the most thought-provoking thing I've heard about on here in a while.

My thought is; What the hell.....Try it!  I honestly don't see any reason that it wouldn't work quite well.  The key is putting the protective coating over it as the basic foam stuff doesn't tolerate normal automotive environments (high wind, water spray, dust and dirt, that sort of thing) but the bed liner over-coat would mitigate that, right?  Put a nice, hard shell on an otherwise squishy captive-air foam.  You could run a couple of inches or more of the foam in the void between seat and firewall and then coat it.  

The trick is somehow proving that it really works as a sound deadening medium (and I believe that it should - I remember working in an anechoic chamber at IBM once, that had foam in the walls).  If you could measure cockpit noise level on a stretch of road, then put the sound stuff in and re-test for sound level, now THAT would be the Bee's knees.

i used b-quiet everywhere on my speedy. floors, front and rear firewalls, engine bay, and inner doors.  made a MASSIVE difference.

i used this stuff on my VW bus:

http://www.rona.ca/en/multipur...ng-membrane-74165154

it is a little thinner, but looks, smells, and performs the same as the b-quiet and waay cheaper. 

I used a Dynamat knock-off brand sound deadener on the back wall area, and pretty much the entire damn car.  The Extreme version of Dynamat is about 67mil thick, the stuff I got measured 80 mils.  The MurderMat stuff was way too expensive.  I think I paid about $150 for 100sqft.

This Amazon stuff is similar to what I got minus the logos: http://www.amazon.com/FatMat-S...nstall/dp/B00DYAF9FY

Sound Deadener material thickness comparison:

Engine compartment install.  80mil sound deadener, then sprayed with truck bed liner:

Back wall area and pan 80mil sound deadener install, under carpet.  Doors got inside and outside panels covered, as well as were stuffed with foam:

To answer your questions about whether or not it helps, I can't really tell because I don't know what the car was like without it.  What I can tell you is that I don't have a single rattle, vibration, or squeak on the road.

I don't think you'll have any trouble pulling up your carpet to install sound deadener, then simply spray adhesive the carpet back down.  Even 80 mils is less than 1/10 of an inch.  I stopped mine about 1/4" from the edge of the carpet, so you can't tell it's behind.  Definitely use the 3M heavy duty green can spray adhesive.

TP:  That is an incredible application.  As you said, every square inch, Holy Shyt!!, as my favorite Canadian friend would say.  My plan here is not to pull up carpet.  If I had thought about it beforehand, I might have had something like your deal here done when car was built.

Gordon: This new outdoor foam product specifically says it is waterproof, and will hold up in the elements.  While related to regular expanding foam, it would present itself as something a bit different.  Once it is set, I figure it could be smoothed out, if desired, using a coarse file or wood rasp.  The set urethane foam is pretty easy to shave off high spots.  The bed liner product should give the whole thing another level of weather resistance (it will never see the sun, so that helps plenty) and of course it should add to the sound proofing thing.  As to measuring sound pressure levels before and after, I don't have a silly-scope either, and don't really know how to do that.  I suppose there are hand-held instruments, but I don't have one, and would not go buy one.  Hmmmm . . . on second thought, maybe there is an app for that?  Use my smart phone??   I'll look into that.  Thee is an app for everything, as I am slowly learning.  And it's worse:  not just an app, but maybe ten or twenty.  More later . . .

Kelly, if you sand or break the surface of the foam it will no longer be water proof. Breaking the skin is a no no.

T P posted:

I used a Dynamat knock-off brand sound deadener on the back wall area, and pretty much the entire damn car.  The Extreme version of Dynamat is about 67mil thick, the stuff I got measured 80 mils.  The MurderMat stuff was way too expensive.  I think I paid about $150 for 100sqft.

This Amazon stuff is similar to what I got minus the logos: http://www.amazon.com/FatMat-S...nstall/dp/B00DYAF9FY

Sound Deadener material thickness comparison:

Engine compartment install.  80mil sound deadener, then sprayed with truck bed liner:

 

Back wall area and pan 80mil sound deadener install, under carpet.  Doors got inside and outside panels covered, as well as were stuffed with foam:

To answer your questions about whether or not it helps, I can't really tell because I don't know what the car was like without it.  What I can tell you is that I don't have a single rattle, vibration, or squeak on the road.

I don't think you'll have any trouble pulling up your carpet to install sound deadener, then simply spray adhesive the carpet back down.  Even 80 mils is less than 1/10 of an inch.  I stopped mine about 1/4" from the edge of the carpet, so you can't tell it's behind.  Definitely use the 3M heavy duty green can spray adhesive.

This is awesome! Great work! Exactly what I plan to do when I get the body....

Yo, Bill -- I get that, and the reason for the bed liner applique over the top is to seal it up for sure.  That said, this new outdoor foam is a different product than ordinary gap sealing foam, which is yellow/orange.  This stuff is black.  My car builder (JPS) uses the normal orange stuff to seal off seams and such, esp'y around the front yoke.  Where I can see this stuff, I have liberally applied regular spray-on undercoating, not trusting the regular stuff to be water proof, whether unmolested or sanded down.

OK folks, I was right, there are many apps that measure sound intensity with a smart phone (Android) , and so I downloaded one, and will do a true scientific test. Under what conditions should the testing be done, aside from before and after the application of the sound proofing?  Also note that this will not be a quick response.  It was 12.6 deg F last night, and snow is supposed to be on the way.  Just sayin' . . .

Looking forward to the results as I have been thinking of doing something in the same lines as you've mentioned.

TP, outstanding job!

It's nice to have that solid door feel when you close the door, material on the pan makes the car free much more solid and not tin like. When it comes to the engine compartment aside from reducing the engine noise which really comes from the carbs and exhaust one should look at keeping the heat from the exhaust moving up into the engine compartment. Whether you use a similar type of material on the existing sheet metal which covers the area between the engine and frame/body or use a thicker gauge of alum or sheet metal material, the goal is to keep the heat from rising into the engine compartment. One negative side when using the sound deadening material is the extra weight. That's why the new spray on materials are becoming popular. 

A solution to keeping exhaust heat from rising up into the engine compartment.  Plates mount to the lower box frame and seal to the body fiberglass:

Kelly:

Test that puppy with the top up, windows in, same road, same speeds.

That should minimize outside noise invasion in the study.

Nice work, TP.  You might wanna consider letting us know your name before the jokes about your nickname start.  I know this bunch.

Updated.

Lane Anderson posted:

Nice work, TP.  You might wanna consider letting us know your name before the jokes about your nickname start.  I know this bunch.

Hmmm, hitting the Tullamore Dew again Lane?

I guess you didn't notice that TP calls himself Trevor.

Trevor does some really nice work.

WRT engine tins to separate lower heat from upper sections, I hear that aluminum siding works very well. Easy to cut to shape, can be had in many colors, and will not rust.  You may ask how I know this.

Paul, Paul, Paul...  Your mother and I debated about keeping you but I said "eh, why not".  Silly me. 

Ahem, you note that he updated his name, or were you not paying attention? 

Lane Anderson posted:

Ahem, you note that he updated his name, or were you not paying attention? 

Touche, sir Lane. No I hadn't noticed that.