wood or foam for sound deadening which is better for a z partition?
does spray rubberized undercoating help the road noise behind the seats of a Z and over tires and trunk area, daily driver need to get quieter as roads horrible here for noise. thanks.

 

i installed a pre-cut insulation kit really didnt do much, i just swapped tires from Dw's to RE760's and that helped out a lot i'm also looking in to a partitions this is my daily also and its loud ges to me on the longer drives

 

I installed the RE706s and saw a reduction in the noise level right away. Added the partition and tray and made it even better. I have been told that the under carpet insulation will lessen the unwanted noise also, but I haven't used that. Every little bit helps. I was not trying to get the car silent, just a bit quieter. I'm happy with the results that were achieved with the partition and tires. Hope this helps.

 

The car was designed in a manner that "quietness" was way way way down on the priority list if on the list at all. If you're looking for a more mild mannered Vette this is probably the worst choice, IMO the noise isn't so bad really....I had a G8 GT that started out much quieter than any corvette out there and by the time I was done modding it (intake/throttle body/full headers 2.5" exhaust no cats etc) it didn't really matter how much insulation came from the factory it still was loud as hell.

My point is you're starting point is a super light all out race car with no sound deadening to speak of from the factory, and it has a "loud" exhaust from the factory and very wide short side walled tires...you're kinda backwards engineering it- it's never going to be a "quiet car" if you put on "quiet tires" you are sacrificing a lot of performance. More sound deadening equals more weight, before you know it you got a Z06 that weighs the same as a base coupe and tires that underperform.

I'm adding the partition just to keep stuff flying around, but I'm not happy about the weight gain- my $.02 the most noticeable sound improvement you'll find is by ripping out the seats and carpet and laying down some dynamat- the improvement will be staggering I'm sure.

 

well then i'm 1/2 way there, I like RE760's quiet and better ride quality imo but the Dw's did give the car a slightly better handling but the front was 275 so i think that played a part


C5Dobie sorry if it pains you to see us want to enjoy are cars more but i'm not a pro driver and its not a track ***** its a daily driven street car and the little performance we are giving up for comfort for me its worth it and by the time i'm done modding 20/30 lbs will only help with traction

 

I bought my '04 Z as a street/track car with, with track being the primary use of the car. For the first 3 years, that's how it was used but now I am driving it on the street more. On the track, I want it as light and loud. However, on the street when I want to take a road trip I found it to be really noisy and annoying after awhile. I've added a wood board partition along with the tray and that helped a lot, but it's still loud. In some defense my headliner is out right now and that's not helping.

However, my point is I don't think trying to quiet it down on the street is a bad thing. I don't really notice the added weight on the street and take all the heavy stuff out when I track it. It would be much more enjoyable on trips if you weren't listening to load back ground noise the whole time.

Just my $.02. Maybe I'm getting old.

 

In that case - what I think would help you starting in significance #1 exhaust (if you got an exhaust that drones), #2 tires - softer tire = quieter tire, the RE760 may be helpful in that regard, #3 - the dynamat would be a big reduction as much of the noise (and heat) comes from underneath from what I can tell.

 

You have to look at it as making a number of small changes and the net result is that it all adds up.

There are several things you can do to significantly reduce the noise.

First you need to understand that there are two major noise sources, the rear tires and the exhaust. Acoustics are such that if you reduce a specific source a good bit, then the other source predominates and you need to attack it to get any further improvement. For that reason you go after the biggest noise source first and then when the other predominates, you go after it.

As others have noted, the rear tires introduce a lot of noise and the plastic wheel wells don't do much of anything to stop it. Since the rear tires are close to your ears doing the wheel wells is important. If you have an aftermarket exhaust and it's loud then attacking the rear wheel wells isn't going to do much. Pick the thing you hear the most first and go from there.

If you have a stock exhaust, then the tires are the loudest and you need to go there first. In that case it means adding a higher mass damping material to the wheel wells and floor. The floor is just thin plastic and by adding 10 pounds of Dynamat to that area will help a lot. The second area that you want to add some Dynamat is the area of the back wall of the trunk area near the exhaust. In the frequency range we are talking about here, mass stops sound, so light stuff doesn't get the job done.

The second thing is you can do is block the sound path, that is the partition and it works. An important point is if you are blocking the sound path you want to make sure the fit is good (minimize gaps around the partition) and then have a partition with some mass. The frequencies you want to stop are low frequencies and mass is what stops them. For that reason a wood or fiberboard partition is much better than foam.

Lastly you want to stop the reverberation in the trunk area and in the cavities ahead of the rear wheels. When you add the partition the noise in the trunk area actually increases. That's because the sound reverberates in the trunk and while it is more quiet in the cabin, if you don't attack the reverberation in the trunk it's not as good as it could be. You want to find an acoustic foam and line the inside of the trunk lid as well as any areas that aren't carpeted. The foam I used weighs nothing and deadens the trunk area. Also make sure the back side of the partition has a foam or carpet on it so that it's dead too. Bottom line is that a partition works better if the cavity is dead. Same thing for the tire noise. If you stop tire noise with Dynamat, but don't deaden the cavities ahead of the rear wheels the Dynamat doesn't do much good.

Do all of the above and you won't have 15 pounds added, but you'll have a car that is a lot more pleasant to drive on a daily basis. I did all of the above and before I couldn't use my cell phone in the car because it was so loud. Now it isn't Cadillac quiet, (heck it isn't even Chevy quiet), but it's enough better that I can hear and talk on the phone so it's definitely better.

 

^What he said, and I hope to do all that this winter on mine. Have the kit already, just need to do it. Same time replacing the "Blows" speakers with Infinity Reference and a Sub. I'll have a much better sound stage and will be able to use the mobile phone as well. And since I'm tall and skinny, a few added pounds don't concern me much.