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i refuse to give up in my quest to get superb sound deadening at a low expense, haha... and w/ the last couple weeks, i've been asking questions, digging up old archives, shopping around, and generally weighing my options... my next question now is this... a lot of people like to use some type of foam on top of the dynamat type material in between the metal panels and the plastic trim panels... but my question is this... y not just use home fiberglass insulation... you know, the itchy, fluffy, pink/yellow, pink panther stuff... the stuff is made w/ sound and heat insulation in mind, and is rather cheap and relatively light weight... now i know you prob shouldn't use it inside the door cavities (because of the moisture), and i know that MOST of this stuff is very thick (10 to 20 inches or so)... but you can buy it in thin layers too (1 to 6 inches)... like i mentioned before, the stuff is relatively cheap at $.50ish a square foot (the thicker the layer is, the better deal they give you)... has anyone ever thought of this stuff or have good reasons not to use it???

also, i believe it was "perhapsadingo8yerbaby" who mentioned he used a ceramic tile mastic to coat his entire trunk area as the main sound absorber (instead of the expen$ive dynamat stuff) and reported it worked well... i was thinking about similar products, but wanted to find something that would dry to a more "gummy" or "rubbery" coating (as i'm told this ceramic tile mastic stuff dries like concrete)... i thought about tar... black coal tar to be exact... you know.... the stuff you see used on road pavement and also piping and so forth... don't know about the cost of this though... also seems like it would be messy...

anyone wanna help me out?

That itch stuff you were talking about sounds like a good idea, but if you actually think about it. As soon as it gets moist its a pain in the a-- to get dry again. Pluss once wet it would not have the same effect as it did when its first put in. Also im not too sure but breathing that stuff in is not good for your health.

But allong those lines, you can buy cavity filler for household walls,
My old man works in constuction and he says its available
1) fire resistant,
2) water resistant,
3) fire and water resistant,
4) Acustic
it comes in a tube and sprays/squirts on, it then expands, and is full of bubbles. Its then drys quite hard, and could be shaped or sanded to fit.

Never tryed it but supose it might help. If you try it let us know how it goes.

yea i think i know what you're talking about... it sprays like foam and expands... might try it but would want to see how it works before i go spraying my whole car w/ it.... stuff might expensive though, not sure...

what about tar? anyone?

I wouldn't recommend the fibreglass ceiling insulation. To work with sound it would need to be compressed so you'd need to install a sheet of something over it to compress it - probably not an option.

We were wiring motel units once and common walls (between rooms) were made of 2 sheets of 20mm Gyprock (plasterboard) each side and about 4 layers of fibreglass insulation compressed between to reduce noise between rooms. While it was pretty quiet, you could still hear things through the walls like loud TVs, laughig, etc. So I'd have to say for acoustic it wasn't the best.

The foam stuff is pretty cheap but I haven't seen it used for acoustics, but if there is one made for that purpose it might be worth a shot. Experiment with it first - try and get an idea how much it will expand before you put it in the car as you might be in for a suprise!

Home-use spray foam cavity filler-insulation would be a risky application. Most brands expand significantly as they dry so it could end up where you don't want it to go. The instructions warn that using it to seal home windows can cause the window frame to warp or crack under expansion/drying pressure. There is a type that says it minimizes expansion. I've used it around the house but the stuff is still tricky to use, incredibly sticky and impossible to remove easily.

A "tar" or similar undercoating type material can take weeks to stop stinking up the interior after application and even then, on a hot day, you'll be hating life from smelling that stuff cooking inside.

yea u're right, didn't think of the smell... i'll have to check into the foam stuff

...and the quest continues

I got to thinking about this question when i was at work today and we were hanging a suspended ceiling so i asked my boss if he thought that the tiles that you use in a suspended ceiling would be good for sound insulation and he was like hell yeah this stuff is made for absorbing sounds so it dosent reflect off the roof . So i put a bunch of the tiles in the back of my car to take home and even with them just sitting back there the sound was quieted 10 fold. So what i am going to do when it gets warmer again is go buy some foil tape (you know the kind that they wrap home a/c units in) and tape the tiles together (2 layers) and tape them down to the trunk then put tape all over the top until it is completely covered. Now in my opinion this is going to be the cheapest and easiest way to work great with deadening the sound of your exhaust seeing as how the sound was so much more quiet with them just sitting back there losely and the tiles are very cheap (well for me they were free) and you can pick them up at any local home improvement store.

dont know what kind of tiles you're talking about... do they have a specific name... what do they look like?

Here is the link to the tape that lowes carries http://www.lowes.com/lkn?action=product ... -133-40999 and here is the link to the tiles http://www.lowes.com/lkn?action=product ... 365-61-933 Hope this helps you out and as far as i can tell this is the best and cheapest way to go. Also it is very easy to cut with a razor then just tape at the seems. I will be updateing you guys on how it works when the weather gets warm enough to do it.

hey thanks a lot... just another option to think about i guess...

let me know how it works for you!!!

NP... and i hope i will get lucky and get a warm day soon so i can go ahead and do it.

did anyone ever try out the acoustic tiles in the trunk?

thanks