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:
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
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:
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Floor After:
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Front Door After:
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Frequently asked questions:
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
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.
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.
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.
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:
