Some weeks ago I bought a sheet of Dynamat Extreme (4sq feet) to check out if it really helped about the rattling. I knew 4sq feet was pretty much small, i couldn't even fill half of my trunk lid, but I just wanted to know if it really does a difference. (Im short on my budget haha)

I thought it did, because at this time I was using my sealed box, but when I put back my ported box, rattling was horrible. When I say horrible, I mean that I set my sound as little as 5-6 (there is little to no bass inside my car, even if the rear seat is opened) and my trunk lid actually rattle... I know ported box causes air displacement because of the port, which causes more rattling, but at 5-6 volume there is almost no air displacement from the port, it shouldn't be rattling at all since the volume is so low.

There are few things that I know for now :

-I know my sheet was not correctly installed. I've read that you are supposed to stick dynamat to as much surface as possible, which means inside the trunk lid holes too, so it will strenghen the body and make it less likely to vibrate. (Like I said, I was short on dynamat anyway)

-Protege's body is cheap as ****, so it will likely vibrate more. (It's a protege sedan, not a protege5 btw)

- When I open my trunk, there are little to no vibration anymore, even at max volume. (pretty logic since there are actually no more pressure inside the trunk)

but the rear deck (where the rear speakers are) is just a thick cheap piece of metal, it will vibrate no matter what, even if my trunk is opened, so I definitly need to strenghen that one

So that's the info I have, now my question :

What is the real meaning of sound deadeners, to strenghen the body, or to reflect the sound? (or the two) If it just reflect the sound, does that mean that I have to put sound deadener everywhere as possible on my trunk? or just the parts that are more likely to vibrate.

Since there were no difference with the sheet of dynamat i've put, is there any chance that if I invest on more to cover all my trunk lid (and that damn rear deck panel) it will rattle no more? Will I need to cover the whole trunk? Should I junk my car? (j/k )

I'm pretty short on my budget so covereing the whole trunk is gonna be hard for me. But I don't want to invest on the lid and rear deck for nothing.

What are your opinion on sound deadeners, is dynamat the best? I know there are some alternative that are cheaper since I do not have a lot to invest (i'm not talking about seal n peel, I know it's bad and it will smell horrible for months)

Btw, I have a Fi SSD 12" and kicker 750.1, it's pretty strong but it's not like I would have a 3000wrms system that would shake the whole car so I know it's possible to stop the rattling

And only the trunk is rattling (with some parts of the body like the rear bumper and a piece of metal under my floor, but by rear bumper is just not screwed and I'm gonna remove that useless piece of metal anyway) so I won't really need to do the doors.

Thank you, and sorry for that long post, I wanted to give as much info as possible

Edited September 10, 201015 yr by Nyrithz

sounddeadenershowdown.com

or Secondskinaudio.com : they have a sub forum here.

They're both cheaper and more efficient than Dynamat.

They will give you good informations about how to use their product.

Don't use peal&seal product that you can find for house, roof, buildings !

Good luck !

You don't need to sound deaden, you need to mass load. You have to get those panels heavy enough to withstand the pressure and fill in cracks so that they don't vibrate against each other. Find something that's heavy and stick it on there. Same with the back deck. Some people have success using expanding spray foam to get between panels that are vibrating against each other, but be careful with it because it can expand a LOT and actually bend your panels.

I myself had a lot of success with expanding foam. The cans are about 3-7 dollars a can, the method i used was put a little in wait for it to expand, then put more if it didn't fill it entirely i'd put more in so it wouldn't bend the panels. It'll make the panels very dense and will vibrate a lot without adding a ton of weight.

Well since the panels are simply vibrating from themselves, not against each other, I suppose mass loading would be better than expanding foam ?

Do you have any idea of what product I could stick there?

Thanks for the info!

I'd foam everything that can be foamed, it's just a good thing to do

some Vinyl / Nitrate Foam will work, I suggest http://www.sounddeadenershowdown.com/products/ccf

I really hate to break it to you, but you need to invest in a LOT of deadening as they are saying. And good luck getting all the rattles out of that car. Another thing that will help is to adjust your trunk latch down until its a bit harder to close.

Also, who made you your box? Did you check that all your box panels are tight? An old box that has been around the block and wasnt built right, will start rattling. Especially if the box ever got wet for whatever reason

I made my own box, and it does not rattle at all there are so much bracings and glue I could bash on it for days don't worry

I will try foaming then. Thank you all for your help!

I really hate to break it to you, but you need to invest in a LOT of deadening as they are saying. And good luck getting all the rattles out of that car. Another thing that will help is to adjust your trunk latch down until its a bit harder to close.

I've done this as well. I didn't want to mess with adjusting the latch and moving screw holes into the body and all that, so I just wrapped some tape around the hook on the bumper that the latch goes onto. That makes it tighter and helped. Tape will tear after repeated openings and closings, but I hardly ever opened mine so it wasn't a big deal. otherwise you could find something a little more sturdy to wrap a time or two around.

I really hate to break it to you, but you need to invest in a LOT of deadening as they are saying. And good luck getting all the rattles out of that car. Another thing that will help is to adjust your trunk latch down until its a bit harder to close.

I've done this as well. I didn't want to mess with adjusting the latch and moving screw holes into the body and all that, so I just wrapped some tape around the hook on the bumper that the latch goes onto. That makes it tighter and helped. Tape will tear after repeated openings and closings, but I hardly ever opened mine so it wasn't a big deal. otherwise you could find something a little more sturdy to wrap a time or two around.

all you do is take the hook off, oval out the hole with a drill, and bam done