C7Driver

Active Member
May 7, 2014
252
2
London
VetteCoins
600
Car
2014 C7
Knew that I wanted to do this mod this spring so got at. Had read with interest all the threads on the forum , had done my previous sports car with guidance from an expert in sound deadening in vehicles.

I used Dynamat Extreme (butyl rubber) as a I prefer it over asphalt based products such as with Fatmat. Butyl always remains pliable, will never dry out. Over the Dynamat I added a closed foam cell application (Frost King Duct Insulation available at HD or Lowes ) to sound proof the bulkhead behind the seats and the rear of the car. Dynamat or similar products stop the low frequency noise best thru absorbing vibrations in the panels, closed cell foam absorbs the midrange and higher frequency sound waves. Put down the Dynamat first then the foam, the Frost King foam has a sticky side as well.

I focused a lot of time on the wheel wells as we all know the tires generate a lot of road noise up into the trunk area. Aside from the Dynamat and foam I also put acoustical insulation (Roxul insulation) in behind the sidewall speaker wells to fill those gaps.

Those speakers are just behind your head and there is a ton of open space that can echo sound up directly from the wheel well, that is now closed up. Odd that I noted on the right side they had already put some acoustical material in the space but none on the drivers side, almost like it got missed during assembly. Obviously GM recognized this area transmits sound from the wheel well up to the driver, too bad they wouldn't be a little more generous with the insulation they put in and apply it to both sides. I literally filled the cavity, bonus of better sound now from those speakers as well.

The noise elimination is significant. My wife who has no play in the game , no panacea effect, she couldn't believe the difference when I took her out yesterday. I would say the road noise from the rear is half of what it was and now very comfortable. No I haven't measured it with a DB meter but don't need to it was a substantial improvement no doubt. Stereo , you hear a lot more depth , more base. The doors and hatch a little tougher to close as the car is tighter so far as air movement. Well worth $250 and about 6 hrs of my time. Here some pics... I took the last pic before applying the Frost King over the Dynamat in the trunk. The wheel wells took by far the most time.

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Looks good, great job. I would like to do something like this but my biggest worry is messing up, ripping the carpets and not being able to put everything back as it was before I began. I'm somewhat OCD and it would bother me if I screwed up the carpets. Any pointers as to the best way to proceed without messing up the OEM matting/carpet? Thanks
 
I posted this reply on another forum with similar questions about this mod probably answers your question... the plastic non mar prybars are available at Princess Auto for $15. I used 20 sq ft of Dynamat (their Trunk Kit) and a roll of Frost King.


The carpet fits fine after putting this in , there is a backing on the carpet that is also for sound insulation so there is room for it to compress a bit. You wouldn't know that I did this mod by looking at. The wheel well covers have a ton of room under them.

The carpet is very easy to remove , pulls right out. Start at the front behind the bulkhead for the trunk section. The piece that wraps over the bulkhead behind the seats just flips up and over the bulkhead. You need to remove the right and left wheel well covers to do this easily though for the trunk section as the carpet goes underneath the edges of these plastic pieces. I have a small plastic pry bar that gets under the edge of both the plastic wheel well covers and carpet to get it started. The wheel well covers are just clipped in , sames as most all car trim, they pull out and you can put them back in by lining up their clips with the receptacle and push in , maybe hit them a bit with your hand. You do have to play with the covers a bit to get around the roof holder bracket but they are flexible. There is actually a second clipped insert in the wheel well cover that can come out to get over these brackets but I found I didn't need to remove it.

When you put the Dynamat in it and Frost King it is nice to be neat , make it look good but reality is nobody ever sees it so as long as you get decent coverage perfection is not required.

This is a bit time consuming as you need to cut , measure a bit for the sound proofing, press it all on. Removing the carpet , wheel well covers , speakers is the least of it probably of the 6 hours I spent at it taking them in and out is no more than 1/2 hour of that. You don't have to be mechanically inclined to do this.
 
C7Driver thanks for the write up, I too was worried about messing up the carpet, after reading your write up maybe it will be a winter project to do....Question did you take out your front seats to do the bulkhead?
 
Nope , no need to take out the seats, move them as far forward as possible and decline them forward. Lots of room to work behind them in the C7.

I may do the floor and door panels next year, my last sports car I pulled the seats out to do that. Not that big of a deal.
 
I did the same using Dynamat. After the install I continued to do the research and learned that an open cell insulation is better and lighter for reducing the sound. The Dynamat works nice but I wish I would have read more about the the open cell stuff ... oh well, still pleased with the results.
 
Dynamat stops resonance/vibration, the lower end of the sound spectrum, foam will stop the higher and mid range frequencies. They work well together but if I had to do just one it would probably be Dynamat as the body panels transfer sound from the moving parts thru vibration into the cabin. The combination works well reducing or trapping sound.
 
I did my car shorty after buying it should have taken pictures. I was trying to cut down on a bit of road noise and heat coming off the tunnel as my feet would get hot wearing runners on warmer days, Gf liked it kept her feet toasty warm all the time. So I applied B-Quiet ulimate 1.6mm thick to cabin area, doors, trunk and inner fender wells then I used B-Quiet V comp 3/8" thick ( rubber backed product with foam glued on it) to all horizontal surfaces cabin and trunk area. Upgraded stereo at same time, doors close with more of a solid thump sound. Tunnel area seems a little cooler not as much road noise now. Putting some of the plastic trim floor and trunk pieces was a bit of a challenge but they all fit back on without breaking anything.
I have some of both products left over will post in for sale section on the weekend
 
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