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Discussion Starter #1
Few weekends back I took the opportunity to insulate the rear seats and arches area with dynamat extreme. The idea was to quieten down the clunks from the gearbox and stones flinging around the rear wheel arches! Now although it has quietened it down a touch I must admit I was expecting better results.

Has anyone else done this and been disappointed with the results?

Next question, which is the most efficient way to quite the road noise? I think door cards could be the best bet but can’t find any photos of exactly where to apply the insulation.

Some photos of my dynamat installation



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Hi Mike

I thought the idea of it was to help prevent the vibrations/distortions within the car, coming from the speakers to give a cleaner sound, rather than preventing external noise?

I could be wrong, i'm not an expert and not used it in years but that was always my understanding of the stuff and could be why you aren't getting the results you expected
 

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Discussion Starter #3
Yes you could be right there, maybe I would be better adding a thinsulate blanket layer over the top of the dynamat maybe.


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Put deadening on the outer door skins and some 10mm closed cell foam under the door cards.

Deadening under the front seats helps too.
 

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I've used Dynamat Extreme in the same areas as your photo and found it works well, within its limitations - don't forget its primary purpose is for car hifi and stopping resonance from metal panels when the deep bass notes hit (the metal flexes/vibrates). In that sense you can get good results. The marketing of many brands talk about suppressing road noise etc etc which they will to some extent (they normally contain butyl/bitumen/compacted foam to "block" the air carrying the sound) but are better at stopping vibrations from lower frequencies (Hz). In mine, I do still hear the stone chips in the wheel well though and the clunks you describe. Perhaps you could try an acoustic matting material over the top of the dynamat to act as an additional sound absorber? The challenge would be getting one thin enough to fit under the panels but any decent car hifi place should be able to advise, Silent Coat might have something, there's lots of other brands.

Haven't done my door cards, but I assume they will be like most cars - basically cardboard with a vinyl/carpet covering. That's going to to be hard to make a difference to sound isolation. IF you can get to the inner door skin and be patient applying strips of Dynamat etc that will make a difference. There used to be (ahem, 20 years ago!) a company that made a product you could spray on (was it Stinger Roadkill, does anyone know??) which was great for doors and boot areas so might be worth a Google - would save a lot of hassle.

The car hifi specialists on here will be able to help, I'm sure.
 

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Its easy, just remove transmission and fuel tank then clean underside of floor so its perfect and stick away !!!!
 

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Discussion Starter #9
Thanks for the replies, I think next will be to do under carpet and door cards and report back. I'll also try to find a sound absorbing material to put on top of the dynamat in the rear seat area.

Does anyone have any photos of deadening on the doors?
 

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It goes on the inside of the door skin and some people do the inner frame where the membrane goes.
 

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Discussion Starter #11 (Edited)
Just an update: over last weekend I sound deadened the floor panels under the driver/passenger seats.

I used sound deadening then an acoustic matting material/blanket and I also added this on top of the sound deadening I had already applied on the back seats. I took the car out for a spin straight after and it makes a very noticeable difference to on lowering round noise! Especially at cruising speeds 60-70mph.

On Sunday I removed the door cards and applied sound deadening followed by 10mm closed form sound proof on the door skins, unfortunately I ran out of material but I’m sure this will make another big difference. Another bonus I found the annoying rattle in the drivers door!! A loose bolt in the window regulator.

Happy with the results!




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Where did you get the white material from dude thats what ive been looking for? Nice job BTW, ive also goot some spray on stuff ive used under the car, always noticed a difference on import supras to UK with stones underneath, once underbody sealed they were then a lot quieter.
 

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Discussion Starter #16
25mm and any areas where you can fit more I just doubled it up


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Very detailed job there. Glad to hear it makes a big difference. Does anyone know if the model year 2017 on GTR is much quieter?
 
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