Nissan 370Z Forum - View Single Post

Guard Dad · 11-02-2010, 06:02 PM

Sorry to hear of your disappointment with the upgrade. I'd like to offer the following for your consideration.

Noise can be a real problem and simply turing up the radio or getting a loud exhaust in no way addresses the very real problem of noise fatigue and it's negative effects on driver performance, fatigue and comfort. Having said that, the 370Z will never be a quiet car unless extensive measures are taken, measures that most owners would feel compromise the sports car experience that the Z offers.

Based upon my modest experience and the experiences of several others on this forum you should be able to achieve an acceptable sound environment without draining your wallet.

The most common first step is the application of a Dynamat Extreme type product on the hatch floor and fender wells in the hatch area. Often included in this upgrade is the application of the same product on the doors, as much for improved speaker performance as for sound reduction. The widely available technical information advises that the Dynamat is primarily for reduction of sheet metal resonance (and noise suppression/reduction to a significantly less extent) and really needs to be applied to only about 25% of the area of concern. Then the entire area, including the Dynamat, should be overlaid with a layer of sound absorber/suppressor like Luxury Liner Pro. In reality, most forum members, myself included, simply buy a big box of Dynamat and cover everything in sight with the Dynamat, check the 'Mission Accomplished" box and move on to the next mod. This might not be the sophisticated approach but the benefits are real, it's simple to do, the sound levels are down and the harshness of the sound is reduced as well. If you drive with the windows open this may be all you need. Why? Because the altered acoustics (the cockpit is no longer a sealed enclosure) of the interior change, favorably in my opinion, the character of the noise and no, the improvement isn't simply the wind noise masking the cabin noise.

For me, I wanted greater improvement. Shortly, I will be installing Luxury Liner Pro over the Dynamat and I'll post my results here as soon as possible.

I suspect that a lot of the road and tire noise is the result of the suspension bushings installed by the factory. My guess is that they are on the firm side to accentuate Z's crisp handling, a choice which in my opinion is appropriate for this car. However, firm bushings often transmit significantly more noise than soft bushings. An aside, a number of years ago I upgraded to a urethane transmission mount on 99 Camaro SS M6, I was blown away! What a noise! No joke it sounded like the transmission was actually IN my brain. Needless to say I reinstalled the stock mount. Different tire brands and types can have a similar impact on cabin noise.

You said you noted no improvement after the work was done, I am curious as to exactly what was done, perhaps you could elaborate. If you can still clearly hear every pebble and bit of sand hitting the underside of the car it would make me wonder if they did much of anything to the car. Dynamat is a very popular choice here, and for good reason, however the application of sound deadening mastics have yet to find many fans here. Do you know much about the products that were used? If they had just done the 100% Dynamat treatment (material cost for 36 square feet is about $140.00 from Amazon) I would have expected you to post that you noted a significant (not dramatic) reduction in noise levels since numerous other posts, and my own experience suggest that this would be the expected result. Undercoating the fenderwells hasn't been shown to be especially effective but sound absorbers like Luxury Line Pro do seem to be effective. Application of these products is not difficult but requires a certain attention to detail to get good results. Dynamat installation is well documented on this forum, not so much information is available on Luxury Liner Pro, acoustic mastics and undercoating in the 370Z. I plan to add to that knowledge base in a few days.

If you're interested, you might duplicate my previously mentioned experiment with the blankets, pillows and cushions PACKED into the hatch area. If you feel that this doesn't yield an acceptable improvement, the Z may not be the car for you. Short of loading 100+ pounds of sound deadeners in the car, I don't expect a sound environment dramatically better than I achieved with the Dynamat and the blankets etc. in the hatch. My pending installation of Luxury Liner Pro is simply my attempt to reduce the sound level to that achieved with the blankets without actually having to drive around with a car full of blankets.

11-02-2010, 06:02 PM	#30 (permalink)
Guard Dad Enthusiast Member Join Date: Aug 2010 Location: South Orange County, CA Posts: 422 Drives: 2010 370Z Silver A7 Rep Power: 15	Sorry to hear of your disappointment with the upgrade. I'd like to offer the following for your consideration. Noise can be a real problem and simply turing up the radio or getting a loud exhaust in no way addresses the very real problem of noise fatigue and it's negative effects on driver performance, fatigue and comfort. Having said that, the 370Z will never be a quiet car unless extensive measures are taken, measures that most owners would feel compromise the sports car experience that the Z offers. Based upon my modest experience and the experiences of several others on this forum you should be able to achieve an acceptable sound environment without draining your wallet. The most common first step is the application of a Dynamat Extreme type product on the hatch floor and fender wells in the hatch area. Often included in this upgrade is the application of the same product on the doors, as much for improved speaker performance as for sound reduction. The widely available technical information advises that the Dynamat is primarily for reduction of sheet metal resonance (and noise suppression/reduction to a significantly less extent) and really needs to be applied to only about 25% of the area of concern. Then the entire area, including the Dynamat, should be overlaid with a layer of sound absorber/suppressor like Luxury Liner Pro. In reality, most forum members, myself included, simply buy a big box of Dynamat and cover everything in sight with the Dynamat, check the 'Mission Accomplished" box and move on to the next mod. This might not be the sophisticated approach but the benefits are real, it's simple to do, the sound levels are down and the harshness of the sound is reduced as well. If you drive with the windows open this may be all you need. Why? Because the altered acoustics (the cockpit is no longer a sealed enclosure) of the interior change, favorably in my opinion, the character of the noise and no, the improvement isn't simply the wind noise masking the cabin noise. For me, I wanted greater improvement. Shortly, I will be installing Luxury Liner Pro over the Dynamat and I'll post my results here as soon as possible. I suspect that a lot of the road and tire noise is the result of the suspension bushings installed by the factory. My guess is that they are on the firm side to accentuate Z's crisp handling, a choice which in my opinion is appropriate for this car. However, firm bushings often transmit significantly more noise than soft bushings. An aside, a number of years ago I upgraded to a urethane transmission mount on 99 Camaro SS M6, I was blown away! What a noise! No joke it sounded like the transmission was actually IN my brain. Needless to say I reinstalled the stock mount. Different tire brands and types can have a similar impact on cabin noise. You said you noted no improvement after the work was done, I am curious as to exactly what was done, perhaps you could elaborate. If you can still clearly hear every pebble and bit of sand hitting the underside of the car it would make me wonder if they did much of anything to the car. Dynamat is a very popular choice here, and for good reason, however the application of sound deadening mastics have yet to find many fans here. Do you know much about the products that were used? If they had just done the 100% Dynamat treatment (material cost for 36 square feet is about $140.00 from Amazon) I would have expected you to post that you noted a significant (not dramatic) reduction in noise levels since numerous other posts, and my own experience suggest that this would be the expected result. Undercoating the fenderwells hasn't been shown to be especially effective but sound absorbers like Luxury Line Pro do seem to be effective. Application of these products is not difficult but requires a certain attention to detail to get good results. Dynamat installation is well documented on this forum, not so much information is available on Luxury Liner Pro, acoustic mastics and undercoating in the 370Z. I plan to add to that knowledge base in a few days. If you're interested, you might duplicate my previously mentioned experiment with the blankets, pillows and cushions PACKED into the hatch area. If you feel that this doesn't yield an acceptable improvement, the Z may not be the car for you. Short of loading 100+ pounds of sound deadeners in the car, I don't expect a sound environment dramatically better than I achieved with the Dynamat and the blankets etc. in the hatch. My pending installation of Luxury Liner Pro is simply my attempt to reduce the sound level to that achieved with the blankets without actually having to drive around with a car full of blankets. Last edited by Guard Dad; 11-02-2010 at 08:46 PM.