I've searched a bit on rattling and did not find the answer to my question. I think I know that answer but I better ask you first before I make a mistake.

I got a sub in my trunk, and when I play it somewhat loud, the rear bumper rattles like hell. I know some of you will say the solution is to turn down the volume, but I would like a more permanent solution.

Would dynamat really fix the problem?

What causes the rattling anyway? Is it air going into every hole and bouncing back and forth, or is it just plain vibration?

(sorry I know forth shouldn't be written like that, but I don't know the right spelling)

 

I have the same problem, but I find that I have more rattle in my rear tail lights than in the bumber.

 

first off... yea, forth is right that way, lol. so, you're good there. and, i'm having the same problem, just too cheap for dynamat. my front bumper actually rattles occasionally, too. so, this question goes for me too.

 

you can lower the latch of the trunk a little bit which would make it close tighter...but you really have to slam it to get it to shut. basically your just going to have to live with the rattle. your moving a lot of air in that trunk and without like a few thousand invested in sound proofing and trunk strapping it will rattle no matter what. its a thin piece of metal...its going to vibrate.

 

If you can port it somehow, that might help. The reason it rattles is because the sound pressure has no where to go, so it goes into the frame and everything inbetween. It will make anything that isn't buttoned down tight rattle. Try lowering your back seats and playing it at the same level that you did when you got the rattle before. It should help some. If it does try putting a port into the passenger compartment somehow (don't know how, but im sure someone can figure a way) Best way would be to make an escape for the air to outside, but that would defeat the purpose. Would however make a real nice sound outside the car . Other than that try stifening things up or putting sound dampaning material on the inside of the trunk (ie egg crate foam or equivilent)

 

Are daping material very heavy, or would it just add a few pounds to the car.

 

could always try what some members have done, even though I dont think it helped tremendously... you can put that expanding foam-in-a-can stuff and spray it between all the bars holding the trunk together.. but I dunno

 

I'm gonna ductape the whole freakin thing

 

I was kidding of course

 

Okay... here are some of the things I did to quiet the rattles of the rear bumper.

1. Back your license plate with Dynamat, and use 4 bolts, to secure it. (Yes, that's right BOLTS. Not those nylon ****ers they use at the factory)

2. Remove the rear bumper, and dynamat the whole thing inside. USE A HEATGUN. It's gonna add pounds, but it's all in the name of less rattle. When attaching, put some foam weatherstripping betwix the rear bumper and most of the mounting points.

3. Secure all wires, tightly. I used Gaffers tape, but failing that, duct tape will do.

That's all I did, and I waved goodbye to rattle.


Now if it's the lid, you're gonna need to do a bit more work. Sprayfoam is the shiznizzle for the job. Just get some MINIMAL expanding foam. NOT the regular stuff (it'll expand too much and buckle the trunk lid) Then being very careful (because minimal will do it too) spray the foam in the holes in the lid renforcement bars.

 

my advice
point your subs into your seats if at all possible, you loose no sound and they will actually hit louder with more airspace when you lay the seats down

if thats not possible cut a hole behind the folding armrest and lay it down that will vent out all the air in the back and reduce the rattling or you can drive around with one of the seats down

slightly easier fix/cheaper/not as good as higgity
take some c-clamps, the tiny ones and clamp your bumper to the body much tighter, as far as license plate goes i just took mine off bent it outward and put the 2 bolts back in so now it doesn't touch the car sept where the bolts are

if your spoiler is rattling just tighten the bolts but not TOOOOO much or you will dent your trunk lid i took mine off and put rubber between the trunk lid and the spoiler, raised my spoiler bout 1/4 inches but it got rid of rattle and no one can tell. all i used was solid rubber from mijer lol works good

totallying i spent like 10 bucks and fixed my prob i am working on doing it higgity's way but it cost mroe and is more work so i say spend 150 on the system rather than dynomat to keep it from rattling

 

Yeah... that's the nice part about free Dynomat, I'm able to use it wherever I want, at no cost.

Though a good cheap alternative is "Peel & Seal" which is a roofing product. Ice and Water barrier works well also. (I&W is roughly $70 for about 1500sq ft)

 

Yeah you just need something that is going to absorb the sound pressure. Egg crate foam will work also, without having to put spray foam in the car. However it will be noticable. It also would need to be secured well and form a complete barier when the trunk is closed otherwise it would only help a little. what exactly is dynamat? if its rubber it doesn't actually stop the vibration, it just gives it a soft surface to hit so it quiets it. You want to stop the vibrations, because eventually its going to shake things apart.

 

dynomat is suff they stick to parts that are rattleing, kinda foamy..absobs the vibration. common display is with a little on a bell and try and make it ring ya cant; just get a thunk no vibration allowed for the bell sound. sorry if this is bad discription all what i remember from putting it in my old car. and ya damned expensive crap..and no not heavy

 

That sounds like it would work then. Good luck getting that rattle down!