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The Bacon Hauler (‘12 Cop Charger)
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Discussion Starter · #1 ·
Despite laying down sound deadener all inside the trunk and spare tire well of my 2012 Charger, I had a wicked rattle back there when the bass notes were especially strong.

I narrowed it down to the trunk lid, and so I put sound deadener on the underside of the trunk lid as well, but that didn’t stop it.

It turned out to be the inner metal shell vibrating against the outer trunk lid skin, and there seemed to be nothing I could do to stop it.

Until now...I hope!

I decided to fill the inside of the trunk lid shell with the expanding spray foam before laying down the sound deadener this time, so hopefully this will work. I will update the thread once I have everything back together and can test it out.

For now, some pics:

Vehicle Car Automotive exterior Mid-size car Windshield
Architecture Space Art
Architecture Fictional character Art
 
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Wow. I would have never guessed that was the problem.

I love how you thought outside the box to(hopefully) fix the problem.
 

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2014 Shaker Boosted 392 Stroker M6
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995995
 

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The Bacon Hauler (‘12 Cop Charger)
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Discussion Starter · #4 ·
Wow. I would have never guessed that was the problem.

I love how you thought outside the box to(hopefully) fix the problem.
It took a while to figure it out. I did so many different things to try to eliminate vibrations, but there was still a source for the really low bass notes, and I finally just stood parallel to the lid looking across from side to the other, and I could see a rippling in the lid surface. Then I had my brother press down with both hands over the whole lid, and that stopped it.

I tried various hacks to stop it after that, but no matter what, that metal shell would vibrate against the outer skin. I could never get anything in between them in enough areas to stop the noise.

This spray foam should do the trick, but it’s still just an idea at this point. I will have to swap all the audio equipment over from my 2012 to actually test out my hypothesis on this.

Ive got my fingers crossed, because if this don’t work I don’t know what else might.

And now, more pics of the rest of the trunk (yes I’m going over board here, but I have several dozen square feet to use up):

995996


995997
 

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Nuke how much weight you added in sound deadening material?

Sent from my Pixel 3 XL using Tapatalk
 

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The Bacon Hauler (‘12 Cop Charger)
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Discussion Starter · #6 ·
Nuke how much weight you added in sound deadening material?

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Well, let’s see, each sheet weighs 13.4 oz, and I have used about 5 sheets so far, but I still have more area I want to deaden like the rear deck and such. However, I have 4 sheets left...so I’m sure I’ll use them all.

By the time I’m done, I’ll have added (13.4 * 9) == 120.6 oz of sound deadener. If I remember correctly from my pot days, there’s 16 oz in a pound, so that means I’ll have added 7.5 lbs of dead weight (in sound deadening material).

That doesn’t take into account the spray foam, but I’m not sure how to quantify its weight now that it’s been applied and has dried. Let’s say it is roughly 2.5 lbs of foam in the trunk lid. That brings the sound treatment total up to 10 lbs of dead weight...approximately.

While any extra dead weight is bad, that 10 lbs pales in comparison to the sub and its box I’m installing. That thing has got to be 30 lbs all together, so 3 times what I’ve added in dynomat probably.

Then there are the amps...those are probably another 10 lbs together, plus the power and ground wires and their distribution blocks...another 5 lbs there...

By the time I’m ready to test my dynomat project here, I’ll have added over 50 lbs of dead weight at least, probably closer to 60 lbs if I were to weigh it all out.
 

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So, sound deadening material weighs less or less is used when sound deadening mats. I figured it would add more weight then that.

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The Bacon Hauler (‘12 Cop Charger)
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Discussion Starter · #8 ·
So, sound deadening material weighs less or less is used when sound deadening mats. I figured it would add more weight then that.

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I figured it would too honestly, but my sound deadening material isn’t actually Dynomat brand, it’s some knock-off brand that gave me a double butt-load of coverage for the same price as Dynomat in much smaller coverage area.

IDK, maybe my math is off, how many ounces in a pound, 16, right?
 

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Yep 16 ounces =1lb

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The Bacon Hauler (‘12 Cop Charger)
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Discussion Starter · #10 ·
There were 20 sheets in the original box, and I remember it weighed just over 16 lbs because it struck me how heavy it was when I got it, so I weighed it. 20*13.4/16 == 16 lbs and some change if my back of the napkin math is right.

So yeah, the dynomat stuff only amounts to a little less than 10 extra lbs in this project.
 

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Not bad at all. I might just need to do my trunk now.

Pretty easy to do? Pull out carpet and what not then cut and "paste"?

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The Bacon Hauler (‘12 Cop Charger)
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Discussion Starter · #12 ·
Not bad at all. I might just need to doy trunk now.

Pretty easy to do? Pull out carpet and what not then cut and "paste"?

Sent from my Pixel 3 XL using Tapatalk
The most laborious part is removing the trim pieces and then wiping everything down with some alcohol/water solution and/or degreaser to make sure the dynomat will stick to the surface.

Once all that’s out of the way, marking up and cutting the sheets is all that’s left...well, peeing off the backside and pressing onto the surfaces, followed by setting it with the little ridged roller.

But no, it’s not hard at all, just takes lots of prep work to ensure a good outcome
 

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The Bacon Hauler (‘12 Cop Charger)
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Discussion Starter · #13 ·
This the second one of these I have done, so I’m gaining experience as I go, but I will say the job only needs to be as difficult as you want to make it.

There’s no need to go all out like I did and try to cover every bare surface back there unless you have lots of extra material you want to use up.

Hitting a majority of each of all the flat surfaces back there would be sufficient, and probably yield just as good a sound from the audio system.

On that topic, I will say the benefit of sound deadening these trunks isn’t so much an increase in the quality of your audio setup as it is a decrease in the ability of the car and the road to detract from your audio setup.

In other words, if you have a marginal system, sound deadening won’t necessarily make it sound better. What it will do is filter out much of the unwanted road noise and exhaust notes that tend to drown out the audio system’s output, thereby making it easier to hear the quality of the audio system.

But if the audio system sucks already, being able to hear that suckage easier isn’t going to be a good reason to do the dynomat stuff.
 

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I have the stock HK set up. For my type of listening the HK set up sounds good. So I can imagine it will be a bit better to my ears.

I know it rattles the trunk though when you are outside the car and I really don't like that. I don't know how many cars I have made fun of when all I can hear is their trunk rattle and I don't wanna be that guy.

LMAO

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The Bacon Hauler (‘12 Cop Charger)
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Discussion Starter · #15 ·
I have the stock HK set up. For my type of listening the HK set up sounds good. So I can imagine it will be a bit better to my ears.

I know it rattles the trunk though when you are outside the car and I really don't like that. I don't know how many cars I have made fun of when all I can hear is their trunk rattle and I don't wanna be that guy.

LMAO

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I heard that. I almost died of embarrassment the first time I heard my rattling after dialing in my system to the way it is now. I didn’t know I sounded like a coffee can full of marbles when I pulled into a convenience store or the street in front of my house.

I will say that if your issue is one of errant vibrations, the sound deadening will be of limited help usually. You may have to just isolate the vibrating piece(s) and focus on making them stop by whatever means necessary.

That’s pretty much where I am now with this 2014. I am doing the sound deadening because I know it will help the sound inside the car, but the spray foam is meant to address a specific rattle I had on the 2012 that I assume I will have on this one too since they are basically the same car.
 

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Well, let’s see, each sheet weighs 13.4 oz, and I have used about 5 sheets so far, but I still have more area I want to deaden like the rear deck and such. However, I have 4 sheets left...so I’m sure I’ll use them all.

By the time I’m done, I’ll have added (13.4 * 9) == 120.6 oz of sound deadener. If I remember correctly from my pot days, there’s 16 oz in a pound, so that means I’ll have added 7.5 lbs of dead weight (in sound deadening material).

That doesn’t take into account the spray foam, but I’m not sure how to quantify its weight now that it’s been applied and has dried. Let’s say it is roughly 2.5 lbs of foam in the trunk lid. That brings the sound treatment total up to 10 lbs of dead weight...approximately.

While any extra dead weight is bad, that 10 lbs pales in comparison to the sub and its box I’m installing. That thing has got to be 30 lbs all together, so 3 times what I’ve added in dynomat probably.

Then there are the amps...those are probably another 10 lbs together, plus the power and ground wires and their distribution blocks...another 5 lbs there...

By the time I’m ready to test my dynomat project here, I’ll have added over 50 lbs of dead weight at least, probably closer to 60 lbs if I were to weigh it all out.
You're going to need to lay off of the TexMex and beer to compensate for all of that weight...
 

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The Bacon Hauler (‘12 Cop Charger)
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Discussion Starter · #17 ·
You're going to need to lay off of the TexMex and beer to compensate for all of that weight...
Neh, I’d rather just remove the rear seat belts and associated hardware instead
 
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be careful with the expanding foam - some types expand quite a lot in volume and could bow the outer sheetmetal skin.

its a common thing I recall on older cars the adhesive filler between the skin and reinforcement would get old and hardened and you'd get rattling - especially on trunk lids.
 

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The Bacon Hauler (‘12 Cop Charger)
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Discussion Starter · #19 ·
be careful with the expanding foam - some types expand quite a lot in volume and could bow the outer sheetmetal skin.

its a common thing I recall on older cars the adhesive filler between the skin and reinforcement would get old and hardened and you'd get rattling - especially on trunk lids.
It’s too late now, if it’s done any damage, I’m damaged!

Although it was pretty much dry by the time I reassembled everything yesterday, and I didn’t notice any swelling on the topside.

Now all I have to do is pull the factory headunit, splice in some bullet connectors to the speaker wires, run two sets of wires from there to the trunk, wire up and mount the amps, mount the sub box, wire it up, and replace all the speakers, which I still need to pull out of the 2012.

seems as though I’m a long way away from being done :(
 

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