Tech: Sound Deadening, Rattle Insulation

[rogue]

While the 300c may be a well built machine, throwing a subwoofer in the trunk sounds like team of monkeys shaking maracas. Rattles are severe on the inside, and evident from the outside. There are two parts to silencing rattles, Sound Deadening, and rattle isolation.

Frequently asked questions:

Why should I sound deaden?

1. decrease road, engine, and exhaust noises
2. experience a less stressful and/or fatiguing drive
3. decrease rattles and vibrations
4. increase the resale value of your vehicle
5. increase SPL (how loud your stereo plays)
6. increase dynamic range of your stereo system
7. decrease resonance and coloration from speakers

Which Sound Deadener should I use? Which is best?

There are various manufacturers of Sound Deadening, and many people have their preference, but they all accomplish the same goal. Sound deadener simply adds mass to a body panel to reduce resonance. Choose whatever fits your budget best. I have personal experience with Dynamat, Dynamat Xtreme, Brownbread, eDead, and Fatmat. They are all about the same thickness, material, and weight. If money is no object go with Dynamat Xtreme. The rest are all equal performers, but the Xtreme tends to stick to panels really well in my experience.

How much deadener do I need to use to be effective?

You can apply deadener in patches (25-50% area coverage) to keep a specific panel from resonating or you can apply it over an entire area (such as the floor, doors, or trunk) to create a sound barrier and thermal insulator.

What kind of tools do I need to install Dynamat?

Installing deadener requires only a few tools: razor knife or scissors, heat gun (optional, but helps get it stickier), roller tool, rags and a solvent-based cleaner (rubbing alcohol also works). You also need basic hand tools for the disassembly and reassembly of your car.

How much weight does a full Dynamat install add?

It depends how much you choose to use. I only dynamatted the trunk area and uses around 50square feet. I'd estimate it weighs about 40lbs.

300c Specific Rattles:

1. The Trunk cardboard "Speaker tray"-
Remove this tray and throw it in your trash can. It causes rattles on the factory system and provides no audible benefit. Removing this piece will also allow the bass from your aftermarket subwoofer to enter the cabin. Removing the factory subwoofer is also recommended.

2. Interior Trunk Panels-
These panels are hollow and therefore resonate like nobodies business when bass slams into them. I sprayed 4 coats of rubber Fenderwell liner to the interior of these panels to add mass. This helped, but the thing that really made a difference was filling the panels with household carpet padding. You should be able to find some at any carpet shop in the dumpster or for purchase. Cut it to fit and apply it using 3M spray adhesive of some kind. Make sure to note the trim clip holes so you don't cover them up. I had issues with these panels rattling against the metal they were mounted to. I used thin speaker carpet to fill the gaps between the panel and the metal they are mounted to. This cushioned the panels and reduced any rattling to a minimum.

3. Rear Deck lid behind the seats-
This section of the car was the largest source of rattling on my 300c. It is also the most difficult to work with and gain access too. It requires the removal of the lower and upper C pillar trim behind the rear doors in order to remove it. I will write a tech post in regards to accessing this. Keep an eye out for "Tech: Removing Rear Deck Panel." Once the deck lid is removed and layed out on the rear seat, close your trunk and play the subwoofer at a decent volume. Place your hands on the various parts of the metal deck to narrow down specific rattles and apply the deadener where needed. I also recommend using rubber or foam weather stripping on all the edges of the deck trim that make contact with the metal deck. This will eliminate the panel rattling against the metal. I also filled the deck with carpet padding to further decrease my chances of rattles once it got all back together.

4. Third brake light-
This specific rattle may have been specific to my 300c, but it was quite evident after all the rest of the work had been done. I removed the unit from the rear deck, and padded the mounting locations with deadener. I also used clear silicon glue to secure the LED circuitry to its casing. The circuit board is loose from the factory.

5. License plate-
Line the back of the license plate with deadener. It took 2 layers on mine.

6. Overhead Console Lights-
The clear lenses of the overhead lights are rested within the console and have a tendency to rattle during heavy bass lines. I cut off the tip of an old credit card and shoved the tip in between the console and the lense to the side. This tightened the fitment just enough to stop the rattle and is not visible.


Some deadening insulation pictures for reference: Courtesy of Anton (Whats your screen name here?) off sounddomain.com

Trunk after deadining:

Floor After:

Front Door After:

[BilboCameron]

Another great sound deadening product is Raamat. Raamat's new BXT mat offers the same perfromance as Dynamat Extreme at nearly half the cost.

http://www.raamaudio.com/index.htm

Rick McCalum is the owner Raamat and his passion for sound deadening was born out of car audio sound competition. He has an extensive installation tutorial on his website.

http://www.raamaudio.com/installing.htm

Rick is also very helpful with questions even if you are not using his product. I you have sound deadening questions feel free to contact him at raam@raamaudio.com

[ktan23]

can you post a pic of the interior trunk panels or where they are located because i don't know what it is.. sorry.. thanks in advance...

[rogue]

Originally Posted by ktan23

can you post a pic of the interior trunk panels or where they are located because i don't know what it is.. sorry.. thanks in advance...

The interior trunk panels are the carpeted surfaces in the trunk. The sides, the panel on the trunk lide, the panels on the lower back trunk. Basically anything with carpet is a panel.

[II kings 9:20]

rogue, how well do the carpet and panels fit after the mat is installed.

[rogue]

Originally Posted by II kings 9:20

rogue, how well do the carpet and panels fit after the mat is installed.

I made sure all my sound deadener fit within the space that the panels occupied and didn't stick out. For instance on the trunk lid, the deadener isn't placed over the entire surface, only where it can be hidden.

After putting the deadener down, you have to poke holes where the trim pins go in to get the panels back on. When you put the panels back in place, the trim pins have to be pushed through the deadener. It actually makes for a more secure fit to the metal than the factory install.

[mikew2069]

What's a fair price for a shop to install dynamat? I went to a local 'Cartoys' (not sure if it's nationwide, but it's pretty well know in Texas) and they quoted me $700 for labor only!!!!!! I thought that was rediculous, but then again, I have no idea what the going rate is.

[II kings 9:20]

Originally Posted by mikew2069

What's a fair price for a shop to install dynamat? I went to a local 'Cartoys' (not sure if it's nationwide, but it's pretty well know in Texas) and they quoted me $700 for labor only!!!!!! I thought that was rediculous, but then again, I have no idea what the going rate is.

Also Dynamat is very expensive which is why I am going with Fatmat.

[mikew2069]

Originally Posted by II kings 9:20

Also Dynamat is very expensive which is why I am going with Fatmat.

Yea, but the 700 was just for the LABOR!!! Does that seem high?

[rogue]

Originally Posted by mikew2069

Yea, but the 700 was just for the LABOR!!! Does that seem high?

Expect a maximum of 4 hours of work from a qualified professional. $80-100 an hour in labor? $200 in deadener. I'd say $400-500 is fair as long as they isolate every rattle and it sounds great when you pick it up.