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Soundproofing a 2018 Grand Sport

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Old 12-28-2017, 12:56 PM
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Hollingswerth
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Default Fantastic Results Soundproofing a 2018 Grand Sport

THE CAR: 2018 GS coupe with 2LT, M7, Comp Seats It is my only car and year round daily driver.


THE PROBLEM:

Way too much unwanted noise coming inside the cabin. I love hearing the engine and exhaust note, but not all the damn road noise, tire noise, rattles, vibrations, gravel constantly spraying the underbody and rockers, ticking of the direct injectors, etc. In other words, the NVH (noise, vibration, harshness) in the GS is way too high for me……especially after having owned Japanese and European sports cars which were more refined.
Another related, but minor problem is that the 6.2L engine & tranny radiate a ton of heat that permeates the cabin and makes the car hot a hell inside during the warmer months. I hate having to always run the damn AC when it’s a cool 60 degrees outside, just to keep the interior comfortable.
As one who wants to drive an ultra-high performance daily driver, the Grand Sport, IMHO, is the best performance bang for the buck out there (except for maybe the ZL1 1LE.) So, how to have my cake and eat it too - without having to spend $180K for something like a Porsche Turbo S??? My solution - buy a GS with the intention of soundproofing / insulating the crap out of it. And, while the interior trim was out, I would proactively fix all the known rattle / vibration issues that have been widely discussed on the forum.


DISCLAIMER:

Before a bunch of people start chiming in, “you bought a sports car, what did you expect?” or “I’ve had corvettes since 1200 BC and the noise, etc. never bothered me.” -----well, this is my sole daily driver and for that I want a car that is more refined and free of unwanted noise. One in which I can comfortably talk with my passenger or listen to some good music, or more importantly, fully enjoy the pure sound of the V8 and exhaust without extraneous noise pollution. For long highway trips, I want a quiet cabin, free from the roar of excessive tire and road noise.
I’m one of those types who likes to modify and improve upon things, and prefer to do stuff once, do it right and be done with forever…when possible. Since this project would entail the pain in the *** process of ripping out the entire interior, I was determined to get maximum sound deadening results for my labors and cash outlay…in other words, the car had better be significantly quieter when I am done.


THE PRELIMINARY RESEARCH:

I read everything I could find online…on the Corvette forums, other car forums, car audiophile forums, industrial soundproofing sites, etc.
I studied up on products like Block It, Exotic Vettes insulation package, products by Dynamat, Noico, Fatmat, Second Skin etc. …and found all of them lacking.
My conclusion: the most complete resource for auto soundproofing can be found online by Don Samford. His website is Sound Deadener Showdown (SDS). https://www.sounddeadenershowdown.com/ IMHO, Don is the guru of auto sound deadening. His website has detailed tutorials on the proper products to use, and the proper layering process. I ended up getting all my products from Don at SDS.
A big thanks goes out to all the posters on the forum who shared info on removing the rear carpet, removing interior pieces, fixing rattles, etc, etc. Especially, thanks to mdiiulio for doing his excellent sticky, “C7 Sound Deadener Install”---when it comes to sound deadening, he clearly understands the proper way to do it..

[The Cliff Notes abbreviated version of this post is simply this: Go to Sound Deadener Showdown Website and read absolutely everything….and you will then know how to properly sound proof your vehicle, and actually get fantastic results for your time and money]


PRODUCTS USED:

Constrained Layer Dampening (CLD) Tiles, 1/8” Neoprene Closed Cell Foam, Mass Loaded Vinyl (MLV), some Hydrophobic Melamine Foam, Velcro strips, a hand roller, and some HH-66 Contact Cement.
All this was purchased from Sound Deadener Showdown Website…..their CLD Tiles are considered to be some of the best in the audiophile industry, and have no odor. Their MLV is virgin vinyl, so there is no petroleum odor. Their prices are reasonable and customer service was top notch.


WHAT I DID:

I removed the entire interior trim and carpet in the rear hatch area.
Up front, I removed the seats, all the carpet, and completely removed all the trim work to expose the entire transmission tunnel.
Nothing was done to the doors.

I followed the instructions/tutorials on SDS website, which basically is: First put down CLD Tiles everywhere. Next, a layer of 1/8” Neoprene Foam on top of the CLD Tiles. Then on top of the foam, the Mass Loaded Vinyl (MLV.) For vertical surfaces, use Velcro strips to hold the Neoprene / MLV layers in place…as explained at SDS website.


*****READ THE SDS WEBSITE FOR DETAILS ON EXACTLY HOW TO DO ALL THIS***


MODIFICATIONS, EXTRA THINGS I DID, AND TIPS:

-For the flat, carpeted floor in the rear hatch area, I did not use 1/8” Neoprene foam between the CLD Tiles and the MLV. I was afraid the total thickness of CLD Tiles + 1/8 “ Neporene foam + MLV would be too thick under the thickly padded carpet, and that the carpet would not properly fit back in place. I decided to utilize the existing carpet, instead of Neoprene foam, as my isolation barrier between the CLD tiles and MLV. So here is the order of components for the flat rear deck area: CLD Tiles, OEM carpet, one solid sheet of MLV, and then on the very top is my Weathertech cargo mat.

- Be sure and totally cover the rear wheel well arches completely with the MLV layer since this area transmits a lot of noise into the cabin. Any gaps left between the MLV pieces will allow sound to come through.

- I placed CLD Tiles on the back of all the interior trim pieces to decrease rattles and vibrations / resonance. I also did this for the interior roof trim pieces covering the targa bar area, and put some Melamine foam under there also.

-With the trim removed, I preemptively employed all of the solutions that people on the forum had devised to eliminate the known, problematic rattle issues.

- Where possible, I stuffed Hydrophobic Melamine Foam behind the all the trim pieces, and packed all open cavities with the Melamine Foam.
Note – Melamine Foam actually blocks sound, which is why I used it in the cavities and behind trim panels. The Neoprene foam, by nature, does not block sound - it is only used as a layer to isolate the MLV from making contact with the CLD Tiles.

- For the MLV over the transmission tunnel, use MLV that has aluminum backing on it in order to decrease heat transference. I used just the plain (unbacked), and less expensive, MLV for the rest of the car.

- While you have the transmission tunnel exposed, it would be a good time to install an MGW shifter….for those who are so inclined.

- I removed the entire subwoofer box, covered it with CLD tiles.


THE LABOR:

I did the rear area on one weekend and then did the front area on the next weekend. Be sure to use a good trim removal kit. I took my time and ended up breaking only one clip in the process. Overall, it was fairly easy and straight forward, it just takes time. I’m 60 and did it by myself. I’m sure the younger, more limber folks could do it much faster and especially if you have someone to help you.


THE RESULTS:

Fantastic. There is absolutely no question the car is significantly quieter. My wife, a classically trained musician with great ears, who drives a Lexus IS350 AWD F-sport, was blown away at the difference. I am overjoyed. It feels like a totally different car. Before, the NVH was irritating the hell out of me, and now the car is just right. As on old audiophile, I initially thought the Bose stereo sounded like pure crap.…now it actually sounds fairly decent and requires far less volume input to achieve a particular sound level. Most of all, the car now feels of much higher quality - closer to what a $75K car should be like. When you eliminate the rattles and vibration, it creates a more solid and vault like feel.

For those who’d worry about diminishing the sound of the exhaust: 90% of the time, I keep mine set to “sport” and it sounds great to me - perfect level of exhaust note inside the cabin. The engine and exhaust sound is more distinct and prominent.… ie. more pronounced now that the cacophonic racket of unwanted competing noises are reduced. I do still hear the injectors ticking, but it is less now.
Further, when driving up and down my street, I no longer hear the pebbles flying off the tires and continually spraying the underbody and rockers. I run my clear targa top most all the time….I expect the car will be even quieter with the solid, insulated top on. Road & tire noise on the highway is dramatically decreased – and this could be reduced even further were I to soundproof the doors – but at this point I’m happy with my results, and too lazy to undertake it.

Regarding any thermal/heat reduction improvements, I will have to report back this coming summer when it is hot again.

For those wondering – No, I didn’t go to the trouble of doing any before and after sound level db readings.


THE NEGATIVES:

The only real negatives were the costs $$$, my time, my labor……and…. god forbid, the fact that I added probably 75+ lbs of weight to the car. I know that’s a lot of weight, but it was worth it to me to have a super comfortable, quiet, solid daily driver. An unintended consequence is a decrease in fuel economy, seriously -in general, I think it’s due to driving the car more aggressively, running higher revs, staying in lower gears longer, and just enjoying the engine / exhaust note more.


BOTTOM LINE:

I love this damn car! Every day it makes my day. Best toy I ever had, and it’s utilitarian to boot….what more could you ask for? Right now, I can’t wait for Michelin to get their rear All-Seasons available for it - I intend to have a separate dedicated set of wheels & All Seasons to run during the freezing months to enable me to drive as aggressively & confidently in the cold as I can with the MPSSs in the warm months.

Hope this helps all of those who would prefer their car to be a bit quieter, refined and rattle free.


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Last edited by Hollingswerth; 12-28-2017 at 01:19 PM. Reason: More accurate title
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Old 12-28-2017, 01:17 PM
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Kevin A Jones
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WOW! You obviously don't like noise and I like your tenacity in attacking a problem!
My '17 GS (convertible) is very quite.
Old 12-28-2017, 01:50 PM
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mdiiulio
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Thanks for the shoutout! The install looks good too!

SDS is an outstanding source and I wish more people around here knew about it.
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Old 12-28-2017, 02:04 PM
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DWillys
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Hollingswerth,
Thx for the writeup. I plan on doing exactly what you did. I've had my C7 for about a month and noise level @ 70mph makes the stereo useless. Not an issue if I'm just running through the gears but occasionally I do drive sanely and then the noise level above about 50 starts to get to me.
Old 12-28-2017, 02:34 PM
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MerakiAutoworks
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I totally understand your view on the road noise.

So you would say it added about 75+ lb of weight..

About how much did it cost you?

And how long did it take you?

-Josh
Old 12-28-2017, 03:18 PM
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ea327
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Originally Posted by Kevin A Jones
WOW! You obviously don't like noise and I like your tenacity in attacking a problem!
My '17 GS (convertible) is very quite.
All convertibles are very quiet!
Old 12-28-2017, 03:52 PM
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quick04Z06
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This would never be a priority of mine (it is a sports car, after all; I have a '17 GS; I wasn't aware the car even had a stereo ), but that is your call and since it is a DD, I understand what you want.

My question is weight--do you know how much weight you added? Perhaps you have before and after numbers? I still lament from time-to-time the stock GS's weight, longing in this respect for the 3100 pound curb weight of my old C5Z06.

Of course, weight and luxury features go hand-in-hand....A Bugatti Veyron weighs somewhere north of 4,162 pounds....

Last edited by quick04Z06; 12-28-2017 at 03:56 PM.
Old 12-28-2017, 04:10 PM
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Originally Posted by MerakiAutoworks
I totally understand your view on the road noise.

So you would say it added about 75+ lb of weight..

About how much did it cost you?

And how long did it take you?

-Josh

I'm estimating about 75-80 lbs...no actual body weight measurements before/after

I also did some soundproofing on my wife's car and brother's car, so I placed one big order. but the dollar amount that went towards the GS was approx $440

I spent a whole weekend doing the rear, and the next weekend doing the front. I took my time
Old 12-28-2017, 04:22 PM
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Originally Posted by quick04Z06
This would never be a priority of mine (it is a sports car, after all; I have a '17 GS; I wasn't aware the car even had a stereo ), but that is your call and since it is a DD, I understand what you want.

My question is weight--do you know how much weight you added? Perhaps you have before and after numbers? I still lament from time-to-time the stock GS's weight, longing in this respect for the 3100 pound curb weight of my old C5Z06.

Of course, weight and luxury features go hand-in-hand....A Bugatti Veyron weighs somewhere north of 4,162 pounds....

Guessing 75-80 lbs, sorry but no actual before /after body weights.

I miss the old days of far lighter weight cars.....who was it, Colin Chapman, who said the most important thing to add is lightness???

I've always modified my cars and will never forget upgrading from a 2000 lb car to a 2700 lb one - the weight difference at the time felt huge. Nowadays, cars are so big, bloated and heavy that I'm happy the GS is a light as it is.
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Old 12-28-2017, 04:27 PM
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What a quality post!

Thanks for sharing OP. I love, love, love my Z51, but the noise from the rear is quite annoying at times. Something like this I would be interested in doing myself. I drive my car not quite everyday, but I do drive it at least a couple times a week at minimum including some 1 hour trips. This would be greatly appreciated as I do listen to podcasts a lot as I drive.

A shame you weren't able to measure dBs before and after!

Last edited by BaconWrappedSushi; 12-28-2017 at 04:38 PM.
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Old 12-28-2017, 05:37 PM
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^^^
With all that effort and time to make an excellent write-up too bad there is no quantified before and after.

My Grand Sport is my 5th Vette Coupe, all have been my DD and fine for me! Like the added sub-woofer in my 2014 and 2017. Helps drown-out the road noise. Have my sound system playing >1000 songs in shuffle mode from the time I start the car. Considering the environment in a car, the sound quality is all that is needed to manage the noise!

Seldom have a passenger and have my iphone set for do not disturb when driving. However appreciate those who have a problem trying to make it better. This feedback appears to be better than others I have read.

Last edited by JerryU; 12-28-2017 at 05:39 PM.
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Old 12-28-2017, 06:23 PM
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Avanti
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"Weight is the enemy." (Ramond Loewy) I don't know what Colin Chapman said.
Old 12-28-2017, 06:34 PM
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DUDE...GREAT POST..ACTUALLY I'M SPEECHLESS..I like the detail's, be it in your descriptive of attack and or pic's...name it...NICE WORK.
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Old 12-28-2017, 07:03 PM
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DWillys
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I've been reading through the sounddeadenershowdown site. Under the testimonials someone did a Toyora FRS. They got about a 30db reduction. That's huge!
Old 12-28-2017, 07:06 PM
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Next time buy an electric Car since you love the “quiet” so much😉
Old 12-28-2017, 07:36 PM
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DWillys
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Still adding people to my ignore list.
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Old 12-28-2017, 08:10 PM
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Gonzo
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Thanks for the great write up!! . ... When I get back into a Vette I will only do a few mods this will be one of them.
My question is where would I find someone to do this for me???
I know I would break a bunch of stuff myself. Where would you search for someone who could do the install?
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Old 12-28-2017, 08:39 PM
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Gearhead Jim
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Originally Posted by Avanti
"Weight is the enemy." (Ramond Loewy) I don't know what Colin Chapman said.
Fred Stout, designer of the Ford Trimotor airplane back in the 1920's, said "Simplicate and add lightness."

Old 12-28-2017, 09:32 PM
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DWillys
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Originally Posted by Gonzo
Thanks for the great write up!! . ... When I get back into a Vette I will only do a few mods this will be one of them.
My question is where would I find someone to do this for me???
I know I would break a bunch of stuff myself. Where would you search for someone who could do the install?
Local car stereo shops, if you can find someone that knows what they're doing. Look at it this way - if they don't know what they're doing you'll end up with a multitude of broken mounting tabs and cracked plastic that could cost hundreds if not thousands to fix. This is one thing you really have to do your homework on beforehand. Yelp is a start, but you really need to talk to some customers that have had the same thing done.
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Old 12-28-2017, 10:04 PM
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HA..I was gonna say,It's a Sports Car..You got that covered.All Good as long as your Pleased.That's all that matters..Good Job.
Sure plenty here will be thinking...
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