C7DriverOnt

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. For information on sound deadening he provides a good resource here... http://www.sounddeadenershowdown.com/

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.

LanceVette

Man, that's gotta be the quietest riding C7 in the world.

Vetteman Jack

You did go all out, but a nice, quiet ride is a good thing.

One question though - with all that added insulation, did you have any problems getting the carpeting to fit tightly when you re-installed it?

kenrobb

I did the Frost King on my C6 coupe and it made a tremendous difference. Have conv now so haven't gotten around to doing it.

rmorin1249

How difficult is it to remove the carpet and then reinstall it? Lots of trim to remove? Any special tools required?

10mm_

Want

C7DriverOnt

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.

Mike Mercury

gotta love it. All I want to hear is the rumble of the exhaust, not road/tire noise.

Frost King is quite good as a light weight solution, but unless the mfgr has changed the formulation recently... you will find that it is open cell foam, not closed cell. On one hand, the open cell nature is part of the reason it works well, good sound absorption. But the drawback in it being open cell is that it will absorb water. You'll only want to use FK on the interior due to this.

I already have a roll of FK sitting in my shop; waiting until I am able to remove the rear coupe carpeting.

rmorin1249

This will be a good project for this autumn. Thanks to the OP for his information.

C7DriverOnt

Most of the Frost King products are closed cell foam but you could be right about the duct foam insulation. Used in interior it will be fine. It has a sticky back coating on one side, aluminum on the other so pretty hard to absorb any water even if exposed.

When you pull out the bulkhead area and the rear subwoofer enclosure GM has installed a bunch of foam products for sound insulation. Probably did the minimum amount required based on their computer simulations of sound transmission.

I think it cut down about 50% of the tire noise , no way to eliminate it just improve on it. Funny story about this, I had a a first aid kit in my storage area at the back with a zipper with two long metal pull ends on them to close or open it. I had put it back in a way that the two zipper pulls were vibrating together on the hiway at higher speeds, thought what the hell is that noise after doing all this work. My wife climbed into the trunk area while on the hiway to investigate (that in itself was pretty funny) , figured out it was coming from the storage area. Next stopped I figured it out and fixed the issue. Doubt I could have heard that before I did this mod. Now of course eliminating all that noise from the rear you hear noise coming at you from other areas, maybe the door panels are next , never ends

EcoBrick Bob

I have Dynamat Extreme in the trunk area in my 2 G8's. This time I went with Fat Mat Rattle Trap. Frankly couldn't tell the difference in the look of the material or how it installed in my Vette. Then I added their butyl rubber product Mega Mat, over the top. My installation looked just like these pix, as I also did all the areas I could around the sides, by the speakers, and some on the back side of the trunk area. NO asphalt smell, just lots of the original glue smells we all have! It's amazing how much quieter these products make our cars. For those who have the Lexan roof, a padded sun blocker also helps lower road noise on long trips. I can't hear my exhaust anymore, unless I open the NPP. Radio sounds much better and has considerably more bass.

There are many products at various prices that are available. Do your own research and pick what looks like the best value and possible combination of products for your needs/pocketbook. Install and enjoy!

I bought considerably more than I needed. Now have enough to install in the back of my EB Flex with the horribly loud exhaust noise when riding in the rear (3rd) seat. You can't hear anything back there!

flynhi

Has anyone tried a product like this:

http://store.secondskinaudio.com/spectrum/

to deal with tire noise when applied to the wheel wells outside the cabin?

flynhi

C7DriverOnt:
Looks like Roxul only comes in large sheets which is way more than I need. Is there an alternative that works as well?

alamo1974

If all that took you 6 hours, it would probably take me twice that amount of time.

rmorin1249

Is ebay the best source for Dynamat Extreme? I plan to only do the bulkhead behind the seats. How many sq. ft. will I need? Thanks.

flynhi

I installed two layers of Damplifier ( eq to Dynamat) and could not tell much difference. On certain types of paving like chip seal, all the road noise I hear is frpm the wheel wells.
So the full treatment is in order

rmorin1249

Interesting as I don't seem to have a lot of road noise. Maybe it's because I swapped out the OEM runflats for non-runflats. I also have a Lloyds Luxe cargo mat in the rear. I'm having second thoughts and may just skip any further sound deadening for now as I'm not displeased with the noise levels in the car as it is.

flynhi

That could be it
I'm running OE 19" and 20" Michelin run flats
Whar are you running?

rmorin1249

18" and 19" Continental DWS O6 non runflats on OEM wheels

nmvettec7

Yes, eBay or Amazon is the best source and a 25 sq ft roll will handle the bulkhead behind the seats. The Fatmat Rattle Trap Extreme 80 mil thickness is what I used in my C7. You don't want anything thinner.

Suggest you make sure product description states 80 Mil in thickness or better. Ebay ads can be misleading while Amazon clearly states it is a 80 mil thickness.