Do the C7's have a plastic wheel well liner like the 5's and 6's? I insulated the underside (facing the cabin) of the liner on these models which helped reduce noise. A lot of road noise is tranitted throughout the cabin through vibration. The objective here is dampen surfaces exposed to the road surface...door panels, floor, sides, etc.

 

waunavet:

Once I pulled the rear hatch carpet it was easy to determine that the floorboard panel under the hatch carpet is a plastic material. I was quite surprised. However, the bulkhead in back of the seats appeared to be an aluminum or metal sheathing material. So, I double layered the Fatmat material in back of the seats.

The wheel wells that are exposed once the plastic covers are removed from inside the hatch are a plastic material as well. It is quite appearant that sound can be easily transmitted into the cabin of the C7, as GM has no insulation or sound proofing in that area of the wheel wells. The wheel wells and rear speakers are cleraly visable in my photos above as well as the plastic floorboard of the hatch area.

 

nmvetteC7: great write up and pics, thank you. I'm getting ready to order either what you did or the 'extreme kit'. Is what you ordered similar to the extreme kit?

I'll post before and after sound readings.

BTW, my '15 Z51 coupe registered 79-80 decibels at 75-80 mph. My '14 Caddy SRX Premium just registered 71 on the same stretch of freeway, same speed. I hope the sound deadening works in the vette - sounds like it did for you!

 

Wow! 79 - 80 db's is loud. According to an online loudness chart, 80 db is like the noise from a diesel truck going 50 mph from 50 feet away. I'll be very interested in what you get after you do the extreme install.

 

The wheel well and rear tub have the same resonance as the older models, add some vibration dampening and noise insulation to take care of it.

 

I agree that it sounds high, and the funny thing is that it doesn't seem that high, but that's what my meter read. Could be the meter, but it's relative and my SRX read 71 on the same stretch, same speed, and that's a huge difference. I'm not really terribly unhappy with the sound level in the vette, but I would like it to be better and it sounds like several have had good luck with the various solutions. I don't expect I'll get near my SRX, but mid 70s would be great.

 

Hopper12:

I am not sure I would call this a "Kit". However, it did come with a cutting knife and roller wheel to press down the backing of the sound deadening material. The product is sold by Fatmat, but the product is labeled as Rattle Trap Extreme. So you may be looking at the same material.

I also corrected the quanity I bought which was 50 sq ft, NOT 100 sq ft for a price of $109.00 from Amazon.

In some areas of the C7 cabin, like the bulkhead in back of the seats I used a double layer. I would think you may be able to get away buying the smaller roll of 25 sq ft. I have material leftover to complete the trunk area in my Jaguar XKR Portfolio Edition.

 

Extremely helpful info and photos. However, it's disappointing that GM would be so cheap in making a $70K car. From all the responses that I am receiving so quickly, I can't understand why the company would fail to address this problem that is bothering so many C7 owners and putting them to so much trouble.

 

IMO you are receiving comments from people who want their Corvette to sound as quiet as a Lincoln Town Car. I, like many others, have owned Corvettes for umpteen years and actually want more noise (like exhaust sound) so we always installed aftermarket exhaust systems. The Michelin run flats are much quieter than the Goodyear's of past years so no complaint from me there either.

Chevy was not cheap in making. $70K car, they absolutely made an outstanding $70K sports car.

 

Good info on installing insulation for those who need to reduce noise however was surprised by you "Cheap" comment!" The Vette body is made from advanced composites that GM indicates is getting almost to a density that it will float on water! Aluminum is 2.5 times more dense! If it's good enough for the body why not the floor and inner panels? Perhaps they could make it thinner by using carbon fiber like the hood but they couldn't keep the car cost under $60,000. They could replace the aluminum frame with carbon fiber as well, it would be lighter. You can buy a McLean P1 made from all carbon fiber, body chassis etc but it cost 1 million dollars! The Vette has used innovative materials from 1953 including the floor and inner panels. Here is a pic:




Corvette has used innovative materials since 1953!

 

JerryU:

I was surprised to see the composite material or plastic floorboard in the hatch area, as the bulkhead behind the seats appear to be aluminum skinned.

I have a 2009 Jaguar XKR Portfolio Edition which is a $108,000 vehicle and also a 2014 Porcsche Cayman 981 which is a $74,000 vehicle. None of floorboards or floor panels are composite material, they are metal. So I made my statement on my thoughts v. the 2 other premium sports cars I own in addition to the C7. I would personally feel better with a metal floor panel in the hatch area, thus my comment made. Sorry you didn't like it.

 

NMVetteC7: thanks so much for the info. I'm going to order that instead of the kit - much more cost effective and it sounds like it worked for you. BTW, XKR PE is NICE! Almost bought the F-Type R coupe. Just didn't have quite enough room for our road trips.

 

Well said. I bought a sports car like my other Vettes’, my 260Z that also had no sound deadening nor did my trucks that I added Flowmasters! The C7 is much quieter than my ’34 street rod! I love the sub-woofer in the C7, it was too hard to add to my C6. I don’t hear any noise when listening to Janis Joplin singing “Cry Baby!” My sound system is on when I get in the car and is seldom off, just crank it up a little if on some funny highway pavement. Guess us “young folks” look for different things when we buy a sports car - I’m only 72!
I also support mods (have over ~25) and installing insulation is straight forward and inexpensive (certainly compared to my carbon fiber side skirts!) I’m sure those that want to add it gain from the great info on these threads, however let’s not expect GM to make the Vette into a luxury sedan. I don’t expect them to include my mods!

 

I’m a bit sensitive to the Vette materials since I worked in Ashtabula Ohio for 7 years where they made the 1953 Vette from fiberglass and according to GM, Morrison is still making the composite material panels. (I did not work in that field at all, I managed a welding R&D lab.) Had a technician who worked at the Morrison plant making the ‘53’s and when GM produced the cars themselves he made the prototypes for the ’55, and ’56 Vettes as I recall.
I believe the aluminum you're referring to is part of the chassis. It is a structural member and adds to the rigidity of the car. I’m in the welding business so aluminum and the new ultra high strength steels being used on cars are of a lot of interest. The Vette uses some 7000 series aluminum that is not weldable so they use rivets etc.! Granted they make the Vette with materials that function as needed at the least cost, thank goodness.
Believe the Porsche and Jaguar are more like unit body construction and the aluminum is probably structural. Recall seeing the all aluminum Jag chassis on display at a trade show and instead of welds they used mostly self piercing rivets and clinching.





Panels behind the seat are stuctural





Very neat welded, and riveted chassis.

 

Very helpful info and perspective for me. I have little problem with exhaust sound. I still fail to appreciate road noise, however. But, at bottom, realize that it's all a matter of trade-offs and personal preference.

 

I've learned a lot from all your expertise. BTW, during my 2 rides in a friend's 2013 Cayman, I seem to have heard as much road noise as in a new vette. I assume that, while sound deadening may help some, there's no avoiding a certain amount of road noise when your head is so close to the rear wheels with little in between.

 

Sound insulation and non-runflats would probably make it very quiet.

 

Question: Was it easy to get the carpet back in place in the hatch area and around the wheel well? A few folks in the past said it was difficult to get the carpet to lay back down in the back.

 

bevo_87:

Answer to your question......Yes, it is ultra easy to get the carpet back into the hatch area. The reason others had a rough time, is because they did not remove the side plastic panels that cover the wheel wells. As you will see in my photos above, I removed the plastic wheel well covers and I actually installed the sound deadening material over the wheel wells. If you don't remove the plastic side covers it would be very hard to replace and push the rear carpet back into place. The only effective way to remove the carpet and complete the job properly is too remove the side covers over the wheel wells and speakers.

If you don't remove the plastic side covers then noise from the wheel whine and spin will continue to enter the cabin area.

1) remove all the tie downs on the hatch carpet...takes a T30 Torx bit. Also remove the tie downs on the sides of the wheel wells. Remove the small plastic cargo net fasteners, just twist and remove.
2) remove the left and right plastic wheel well covers from the inside. (They are just clipped into place). They just pop out of the clips. There i a separate piece to eemove that has 2 clips on the top and 2 clips on the bottom which is the plastic piece that sits on the targo top holder when placing the target top in the hatch. They are easy to see on each side.
3) remove the rear hatch carpet..(it comes out in one piece). The tiny door in the carpet (left side rear chubby) also has clips to hold it in place. Gently put your fingers under the plastic rim and pull up.
4) remove carpet cover that sits inback of the seats.
5) Install Fatmat (Rattle Trap Extreme)...double layer suggested in back of the seats on the aluminum bulkhead. Double layer suggested over the wheel wells.
6) replace carpet that goes in back of the seats 1st.
7) replace the rear hatch carpet 2nd.
8) Reinstall the plastic wheel/speaker covers, they just snap back in place.
9) reinstall the carpet hatch tie downs.
10) take the C7 for a ride and notice the significant difference in noise level then turn on the audio system and enjoy the new sound.

In order to make this project effective, you need to remove the wheel well/spealer side panels.

Don't be afraid of the side panels. Just slip your fingers under the bottom to start and pull the panels out. The clips will release, then you can work around the sides and the top of the plastic panel.

Email or ask if you have any other questions. I am a proven testimonial that this project can be done as a DIY project. Takes about 6 hours with a few breaks to rest your back from bending over.

Here's a photo of where the clips are attached to hold the plastic panel in place.

 

Rattletrap Xtreme + Lloyds Ultimat