I recently installed an MTX 12" in a box in my trunk and of course I'm noticing some rattling. I'm thinking about getting some Raammat and sound proofing the trunk. But i have a question. Does this material absorb sound or simply add firmness to the sheet metal? In other words if I apply the material to the top of the rear deck will that help the sound waves that hit the deck from inside the trunk? Or do i actually need to apply the material to the underside of the deck (inside the trunk), so it absorbs the waves. Hope that question makes sense.

 

Hey Mark:

I recently soundproofed my rear deck. I used a combination of Dynamat and carpet padding. In one of my earlier posts on free air subs, Ali SC4 provided a link to a site where the dood cut a large piece of carpet padding to fit on the rear deck. This solved about 50% of the rattling. I used the dynamat to fine tune the 4 or 5 trouble spots that were especially annoying. Im no expert, but I believe the dynamat primarily adds firmness to the sheet metal and only truly absorbs sound to a minor degree. Either way, its very effective. The trick is to take the entire back seat apart, crank up the subs, and do a comprehensive guess and check. All told, it took me about 5-6 hours to completely sound proof my car. Some areas of attention were the rear deck, interior roof panel, moonroof switch assembly, and both doors. PM if you need any more help.

 

Thanks for the info. I think I might give a shot at dynomat or raammat in the next couple weekends. Hopefully i can get rid of the rattling. The guess and check method sounds great!

Mark

 

The sound deadening/sound proofing does not really absorb sound, it basically adds thickness and rigidity to the metal. So if you add material to the top of your deck it's the same as adding it to the bottom. I think that if you added some foam to the inside of the trunk that would actually absorb some sound. To find the rattling it is definitely a guess and check thing as sportythief79 said. Here's what my RAAMmat job looks like, click the previous button to see the rest of car job, lot's of pics.
Rear Deck
Oh yeah, and raammat is almost the same as dynomat, just not so pricey. I've used both products I like raammat altogether.

sportythief79 - how in the world could you sound proof your entire car is 5-6 hours?????? You must be a very fast worker. I don't even know how much time I spent, more like 40+ hours!!!!! View my gallery to see exactly what I did, pretty much everything but the roof of the car.

Earl!

 

Earl:

Jeez, sorry for such a late reply to this post. . After 5-6 hours on a weekend, I solved about 99.9% of the problem. As stated, I used only carpet padding ($5 from home depot or lowes) and a small amount of Dynamat ($50 on Ebay).

The major problem area was the rear deck. I took the back seats and rear deck out to start from scratch. I played the song "Close My Eyes" by Astroline to search for the rattling. The beginning of this song has about 30 seconds of very clean, very steady bass notes. Needless to say, I had to play it OVER and OVER and OVER again. There were only about 4-5 spots on the rear deck making noise. I literally sat in the back seat the whole time to listen for the exact source of the rattle. They werent too difficult to find after about 2-3 tries.

I custom cut some pieces of dynamat w/ scissors and just stuck it to whatever was rattling. The dynamat has an adhesive backing, so no heat gun required. . There was one loose wire that was causing the majority of the rattle. You guys wouldnt believe how much frickin noise can come from just one loose wire! I just taped it down with a piece of dynamat and poof! No more rattle. After I fixed the rattle on the rear deck, I put the panels and backseats back together ONE PIECE AT A TIME, and played the song again...just to make sure I didnt mess up the work while putting everything back.

The next problem area was the interior roof panel. Specifically, the rattling was coming from the area where the interior roof panel meets the top of the rear windshield. A very nice tech from Ft. Myers Lexus showed me that the roof panel is connected by simple clips. You can very easily grab the edge and pull it down just enough to slide a piece of carpet padding in there. The dimensions were roughly 2 ft. long by 6" wide. Very simple.

Then came the moonroof/domelight switch assembly. This was kinda tough. I had to unscrew the whole thing and and custom cut about 10-12 small pieces of dynamat and stick them in various places. Again, I played Astroline about 45 times in order to perfect it .

Last but not least were the doors. To be honest, they werent much of a problem to begin with, but I figured what the heck. For those of you who have never taken the door panels off of your lexus, I recommend finding someone who's in the know and WATCHING them do it once or twice. Believe me, this will save you some time. Once the door panels were off, I just stuffed another piece of carpet padding in there and it was solved.

All told, this process took about 5-6 hours to do and it solved the huge majority of the problem. The quality of the sound has improved 10 fold. If anybody needs more detail, please PM me.

Doug

 

I'm glad you've solved your problem Doug . That carpet padding sounds like a really good idea, I may have to head over to HomeD and get some for my doors and wheel wells. What did you use to stick the padding onto the car with? I would think that 3M Super 90 spray glue would work well.

 

I used dynamat across my rear deck and cut a piece of bubble wrap to slide in between the roof and roof liner.