DIY Noise Reduction
 

Looked a bit but figured I'd try to put one together. Will Put dB levels in as I get around to it.

Cargo Deck:
Material: McMaster-Carr (1", .75 NRC stuff)

Remove your existing mat. Mine already had an open fiber mat under it. Not sure if all Zs had it or it's something new. Manufacturing date on mine is 7/11/11
Attachment 35531

Trace it out on the foam backing and use a razor blade to cut it out.
Attachment 35532
Attachment 35533

Remove Backing and slide into place. Stretch it around so it fits perfect.
Attachment 35534

Put back your original mat(s) and your done!
Attachment 35535

Took me about 15 minutes.
Measured Improvement 2dB

interesting approach......

How are the results? less road noise?

Just drove around the local streets so far, seems better but that's just qualitative feel. Need to get the dB meter from work and drive it on the couple bad spots on the way to work. Supposed to rain till Wednesday so I drove my old truck in today. Hopefully have some results by the end of the week.

Check out the "Cabin Noise" thread in the General Discussions section for a comprehensive discussion of noise reduction.

LOL Read threw the whole thing before I started. Sounds like you've had some good success with yours after spending some decent amount of $$$. I hate tearing into panels so I figured I'd start off with the easiest one. Wanted to do some controlled sound measurements too so the rest of the people out there can figure out what the biggest bang for the buck is. Also didn't know if nissan has done something with this on the last batch of Zs they shipped out. That's why I showed the picture of the dual mat. Need the dB meter before I really start understanding how best to address the issue.

Please, no just turn up the stereo comments. I know all about noise from my last sports car. 69 Vette, 350SB, performer RPM (heads/intake/cam/lifters), hooker super competion headers with 2-1/2 dual exhaust and single chamber flow masters. I enjoyed it but I'm over the dB levels giving me headaches.

I'm not sure how revealing the db meter will be. I purchased the "db meter pro" app for the iphone 4 and didn't find the information especially revealing. Because of all of the mechanical activity in a moving car I found it difficult to determine the effect of road noise on the overall noise environment as measured on the meter. My readings (after improvements) ran 67-68 db(a) at freeway speeds and the changing road surface didn't make much difference on the meter readings. However I can assure you that the subjective improvement is massive. My hard won advice is to install about 40 square feet of Raamat or Dynamat ($100-$140 if you do it yourself) in the hatch and doors and call it a day. It only adds about 20 pounds and the improvement is worth every pound and dollar invested.

Seems interesting. This should help although technically you need some sound deadening around the wheel wells in the back too to really help.

Right you are! In this context the "hatch area" includes the rear wheel wells, the hatch area floor, the rear bulkhead, the structural reinforcement below the large aluminum cross-beam and the area immediately behind the seats. Interestingly enough, the hatch area doesn't actually include the hatch itself.

Is it difficult to remove the door panels to install the Dynamat? How about for the rear wheel wells? Do I have to remove any panels?

Not hard but a little advance knowledge can save you a lot of heartache.

Do a search on this topic for tips on removing the hatch area trims. The guys doing audio upgrades are always pulling trims, you should check out the audio forum. Spend a little time trolling that forum, you'll learn a lot.

Use plastic trim removal tools (Harbor Freight, about $8) to minimize/prevent damage to the interior.

One member reported a significant improvement and he just did the area exposed after removing the spare tire and styrofoam spacers on each side of the spare. He didn't remove any panels. Check my posts to the "Cabin Noise" thread for what I did, sorry, you'll have to start at the very beginning.

Thanks, I'll look into it.

Just got done doing the road test.
Speed was 65 mph
Data points w & w/o were done in 2 direction on the same stretch of hwy. Attempted to take readings in approximately the same spot to keep it controlled. 2 positions on meter, next to my right ear and approximately 4" off the center of the rear deck. Car was 6th gear, cruise control.

With---Without
74.9---76.8---Head
78.6---80.9---Head
76.8---77.9---Deck
79.0---83.0---Deck

I'll take it.:tup:

Good info. I might just try this :)

Those are substantial drops. The db scale is logarithmic, each 3 db drop is roughly a 50% reduction in sound levels. My reading is 67-68 dba (hit a bump and it goes higher) after all my work, however this can't be directly compared to yours because my meter is an iphone app not a calibrated meter. But for the sake of reference I get about a 66-67 db reading in the house (crickets outside an open window really show up on the dba scale) with the TV off yet there is no way that the car seems as quiet as the house.

Yeah, and if someone coughs 3 feet away it skyrockets. Had to reset it every time I heard a rock bounce off the bottom of the car since I figured it captured it as the peak reading. Still would be nice to get it down a little more. Was looking at getting under the 3 furthest back panels in the back for the next step but mainly focusing on the strut towers.

Also, put the sound meter by the door panels and wasn't as high as the back still. Driver's side was definitely louder. Anyone know why that might be or do you think the road was just rougher on that side?