interior noise

[yerme]

The cabin of my car is quiet, but there seems to be tranny and or tire noise from the rear of my C5 coupe. It's interior noise is much louder then my '87 Coupe ever was. Just wondering if this is unique to my C5 or if others hear this, and if so, if they have found any solution or even improvement to this interior noise. thanx

 

[Don&Kelly]

I had the same problem, in fact I took mine to the dealer because I thought it was the rear end growling ... it was my GY runflats the dealer said - I switched to Firestone Firehawks & my my the rear end growl went away (and the handling improved and ride quality improved - huh - what do you know)

 

[rlb]

The OEM Goodyears are very noisy and the sound proofing in the C5 is marginal. I'm about to tackle the same issue on my 2003 Coupe and have done a little research on the subject. For what its worth, here are few points I picked up.

If you want to reduce road and exhaust noise, the cockpit and rear storage area can be treated with sound proofing material, such as Dynamat, which is specifically designed for automotive applications. High-end mobile audio shops install Dynamat/Dynaliner and competing products. This stuff is quite expensive, so some Vette owners have used low cost alternative materials, such as air conditioning insulation (see link).

There are two different issues involved in automotive sound proofing: controlling vibrational noise emitted from body panels, floor pans, etc., and direct absorption of low/mid frequency noise. Accordingly, specific materials are manufactured to deal with these two sources of noise. A good deal of noise can be reduced with vibrational damping materials such as Dynamat Extreme, while acoustic absorption (stage 2) is necessary to get the very best results.

The most effective "sound proofing" products have a layer (septum) of lead foil, although "mass loaded" vinyl sheets are nearly as good as acoutic lead and eliminate environmental issues. (Extremeliner, a lead composite product, is very very expensive) In any case the key to highly effective sound absorption is denisty. Lead and vinyl soundproofing products are about 1 pound per square foot.

I've estimated the floor, driveshaft tunnel wall, waterfall and rear storage area amounts to about 50 square feet on a C5, so your looking at about 50 pounds of added weight is you use lead or "mass loaded" vinyl. Fortunately, vibrational damping materials (stage 1) are quite light, such as Dynamat Extreme which weighs about 2 ounces per square foot and may do the job without resorting to heavy acoustic absorption materials. I plan to use Dynamat Extreme throughout and layer it with "mass loaded" vinyl in high noise areas.

Some links:

http://www.dynamat.com/
http://www.soundproofing.org/sales/prices.html
http://www.fatmat.com/products.htm
http://www.corvetteforum.net/c5/jochen/sound.shtml
http://mikemercury.home.att.net/sound.htm

 

[99WhiteC5Coupe]

verme,

I agree - the road and tire noise in my 1999 C5 coupe is terrible!

The March 2003 issue of Corvette Fever has an article about a new product that can be used in the rear of the coupe to reduce noise. It is pre-cut and has a tradename of "koolmat". The company web site is www.kookmat.com

Good luck - I intend to purchase this item and install it in my C5.

 

[rlb]

thanks and errata

Thanks for the tip on Koolmat. I tried your link, but it did not work so I assumed you meant: www.koolmat.com

Also, I mistakenly transcribed the weight of Dynamat Extreme and Extremeliner. They are actually .45 pounds/square foot and 1.5 pounds/square foot respectively.

Mea culpa.