help with trunk lid rattle

[aimone 4]

ok so i drive a 76' caprice with 2 treo 15's and my trunk lid is 2 seperate layers ....over the years the two layers dont stick together anymore which causes it to rattle ,sometimes louder than the bass and was just wondering if anyone could give me tips to fix this problem without weighing the lid down where it wont stay open on its own. my first thought was the canned foam stuff that expands but thats alot to fill also my cousin works for a glass company and he gaqve me a cpl rolls of that gooey black shit that seals windshields i just cant it very far into the lid. anyone got better ideas?

[iputon326 9]

you can get some deadener.

theres a couple different companies that sell it.

it should fix your problem.

[Thorshammer 1]

Use the expanding foam to fill in all the hollow areas. Let it seep out naturrally through the holes and cracks. Once dry trim off excess foam. Then put your dynamtt over the entire trunk lid.

That should do it.

[altoncustomtech 773]

These guys are right.... the only way to do any good is by filling the spaces and adding sound deadener of some kind be it dynamat, raaammat, SDS (Sound deadener showdown) or second skin.... The problem is any good solution will weigh the lid down.... you could always add those assist cylinders if it's a real problem...

Edited November 15, 2009 by Alton

[Anthony Collova 2]

Are you talking aobut the bracing on the lid?

If so, what I have found to work pretty good is to use silicone in the area between the layers where the bracing and the sheet metal meet up.

Once it cures, use asmall amount of expanding foam inside the bracing. Not too much though. Then apply a vibration damper over the sheet metal and the bracing.

that works well fo rme..

ANT

[JASON123 1]

Are you talking aobut the bracing on the lid?

If so, what I have found to work pretty good is to use silicone in the area between the layers where the bracing and the sheet metal meet up.

Once it cures, use asmall amount of expanding foam inside the bracing. Not too much though. Then apply a vibration damper over the sheet metal and the bracing.

that works well fo rme..

ANT

2x if anyone would know ^

[CadillacMatt 31]

x2 on what these guys said... I ended up filling the hollow spaces in my lid with Great Stuff foam and covering it in two layers of Damplifier Pro... however the trunk lid has a tendency to close under its own weight now... so if it's a concern to you you might want to stick with one layer or just apply it over the larger flat surfaces.

[Thorshammer 1]

Are you talking aobut the bracing on the lid?

If so, what I have found to work pretty good is to use silicone in the area between the layers where the bracing and the sheet metal meet up.Once it cures, use asmall amount of expanding foam inside the bracing. Not too much though. Then apply a vibration damper over the sheet metal and the bracing.

that works well fo rme..

ANT

I tried this before and had a serious sheet metal bubble from the foam expanding. Thats when I decided to let it seep out and trim it off. No bubbles after that.

[porkchop 304]

seep is good, let it get all it's air...... it will leave pockets that have no air if it is sealed too good, leaving it in it's liquid form..... i have a post about that in my build log.

[bigrank916 72]

seep is good, let it get all it's air...... it will leave pockets that have no air if it is sealed too good, leaving it in it's liquid form..... i have a post about that in my build log.

I remember that. When I saw it I thought, Ohh...wait...you cant do that, can you? No...cant do it. Lol!

[RobClay 20]

Expandable Foam works great

[Anthony Collova 2]

FOr sure

Make sure if you use the expanding foram you use the Minimal Expanding foam from Dap, and do a few test ares to see how mcuh it expands.

Doing the silicaon after the foam expands is the best way to insure that you wont bucklet you sheet metal

Otherwise, just be careful

ANT

[aimone 4]

thanx guys imma give it a whirl with the foam and some dynamat type shiz ....any advice on the deadiner? im needin the best performin stuff for the cheapest price i found some at autozone for $16.99 for a 5' x 5' square but im sure it would take to many layers to get the propper effect......

and the trunk lid its the outside layer of metal then on the inside it has the stamped out sheet of mettal with like 3 cutout holes so technically the inside layer is just about the same as the outside layer just with 3 4" x 4" holes and its not stuck together like it was 30 yrs ago lol and it slaps together......

also would spraying like rhino liner in the whole back half of the car stop small rattles like the back dash and other little random rattles?

[slim2fattycake 85]

what is actually making the rattle? If its two hard materials rattling against each other, putting something that is also hard on them would not make them stop rattling. Close cell foam works for those situations. Can you get pictures for more detail of what you are talking about?

[aimone 4]

yeah man ill get picks tomorrow

[///M5 2,833]

what is actually making the rattle? If its two hard materials rattling against each other, putting something that is also hard on them would not make them stop rattling. Close cell foam works for those situations. Can you get pictures for more detail of what you are talking about?

Indeed. Actually really nearly the only thing that CCF is good for.

[Rudeboy 152]

what is actually making the rattle? If its two hard materials rattling against each other, putting something that is also hard on them would not make them stop rattling. Close cell foam works for those situations. Can you get pictures for more detail of what you are talking about?

Indeed. Actually really nearly the only thing that CCF is good for.

True that! I'd save an hour a day if people stopped promoting the idea that it is a barrier, an absorber or both.

[aimone 4]

the two layers separated and the rattle against each other

[///M5 2,833]

With the trunk open make it rattle and then use your hands to confirm where it is rattling. At that point it will be easy to help. Obviously you could use the brute force approach and just deaden the whole thing, but I'd prefer to solve your problem.

[aimone 4]

the whole thing rattles except the edges all the way around

[jcarter1885 995]

I would say your cheapest solution is to try some expanding foam between the two layers, it helped with my trunk rattle alot (making it sound solid instead hollow like it did before the foam).

I used two cans, only cost $4-$5 a can. Just my .02

[Julian 641]

the foam will help a lot also when i turned my box 360 degrees and made the woofers face towards the front of my car the rattled stopped a lot and didnt rattle as much.

[Anthony Collova 2]

Wow..

That is one hell of a trunk lid man.

So you are confident that you have rattles, and not vibrations right?

Like it has been said in this thread, panels need to be isolated so the rattles can stop.

Expanding foam should work but in your situation, so might an old t-shirt or a sponge. Isolation is the key (provided you have rattles, not vibrations.

If it were vibrations, I would say you could use a liquid damper and spray in to the skin from the large holes to pick up some hard to reach surface area.

In some cases a vibration damper can be used to reduce rattles to, if either the mat is thick enough to isolate the panels, or if the damper reduces the flex of the panels enough that it keeps them from smacking one another..

ANT

[aimone 4]

not tryin to sound like a prick but wuts the difference between rattles and vibrations? vibration is what causes the trunk lid to flex and the flex causes the rattles from the 2 layers smacking together.......I AM A try some foam cause its cheap

an to the other dude when u faced your subs towards the seat did it make it louder inside the car? ive been pondering on rotatin em but its to much work to unbolt the box from the trunk floor

im wantin to turn the around also cause there only like an inch between the box and top of the trunk and theres only like 4 inches on each side of the box and i think thats killing alot of my sound

from gettin into the cab any one think this would help?

[CadillacMatt 31]

not tryin to sound like a prick but wuts the difference between rattles and vibrations?

Rattles are caused by two pieces of metal, plastic, etc. vibrating against each other, and "vibrations" are a single piece of metal flexing and making noise on its own, like the sides of the trunk... dampening material like Damplifier will help 100% with vibrations of single panels but for rattles you need to put something in between the two parts that are making noise, such as expanding foam, CCF, or as Ant said you could even temporarily rig it up with a sock, sponge, etc etc until you find something permanent... I used to keep a couple of towels in the car for this

an to the other dude when u faced your subs towards the seat did it make it louder inside the car?

Depends on the car...not sure about the other guy but for me, my box was too big to let the bass through when they were faced backwards... so I turned them around... if you have pretty good clearance on either side of the box then I would leave them as is. But it never hurts to try it the other way too.