Let me start by saying I have had lot of Infinitis and Nissans in the last 10 years:

2008 G35S sedan (my first and favorite Infiniti)
2011 Maxima SV (temp car for 5 months)
2012 G37S Coupe (wrecked)
2012 EX35
2012 FX37S
2014 370Z roadster
2014 Q50S
2015 Q70S
2015 370Z coupe
2016 QX70S
2018 Q70S

Other notable cars:

2011 V8 Vantage
2016 Audi S6
2016 Audi S5
2018 Audi Q7
2015 Jeep Wrangler Unlimited

I've had/have other cars...but I have always liked the above Infinitis because you can customize and play kind of cheaply. Customizing Audis (and in the past MB and BMW and Volvo) are insanely expensive.

My main complaint with all of them has been road noise. In every car except the G37S and Q50S I had some type of sound deadening put it. Most of these cars were in LA,where the road surfaces are actually pretty good. So I usually just did a tire swap to address the noise which helped. We all know the stock RE050's in any iteration are loud.

I am in Dallas for a bit and roads here are a combination of cement and asphalt. And they suck. So incredibly loud.

On my new 18 Q70S, I swapped my stock sport tires to 255/45 20 PSS 4S. I had done that on my new 16 S6 the day after I bought the car, and on my QX70S. This time I got the newer version. I swear the old version was quieter. The roads here in Dallas are so much worse than in Los Angeles. And because they use cement versus asphalt on 1/2 the roads they are really loud. I just checked my old files (I keep a file on every car I have had) and on my '15 Q70S I put on Bridgestone Potenza S-04 Pole Position. While I was in LA, they reduced the road noise immensely.

My main complaint with the car is the amount of noise transmitted via road. I already have sound deadening in the trunk, doors, wheel wells, and under back seat. My next attempt will be to do the rest of the cabin. We now have a new Audi Q7 - and both it and my S6 had double laminated front and side windows. So it was really quiet.

I've been to 3 stereo shops and they all quoted about the same to do interior...which is around 1600. Seems so high for such a small area. Yes - I know pulling the seats is a pain. My fear is that iI will do the interior, and then find that the noise is really about the cheap single pane glass in the doors.

I had to drive to Oklahoma City one day for a meeting. The noise was to bad I could not even take a call on bluetooth...the other party could not hear me.

Has anyone been successful in addressing this...and if so, what what your process and what was the end result? Did you find it worth it?

I'll be back in LA early next year, so it probably won't be an issue. I remember my first Q70S, as my daily driver then, was very peaceful on my drives to and from work. I'd like it to be the same now.

thx

I think you probably have the most sound deadening of anyone on this sub-forum :p.

Depending on where your preferences lie on the looks vs. road noise/ride quality spectrum, have you considered downsizing your wheels to get larger profile tires?
That would be the single most effective change as most other aspects of the car are locked at design/manufacture.

The Infinitis I've experienced are generally more sporty versus other premium brands... and it could be tricky to balance both super luxurious and super-sporty, especially at this price point of vehicle.
So, the double pane glass and ultra-dampened firewall etc, would be nice, but it might need to be custom as you have done.
What we get is a very sporty (read strong and rigid) construction, BOSE active noise cancellation and a slap on the butt - "good luck out there kids, have fun with the family sports sedan"

My 2012 M37 is the quietest car I have ever owned (except for the nice noises the engine makes), including a 1966 Lincoln Mk III, 1973 Cadillac Coupe deVille, a 1989 Mercedes 300E and a 1991 Toyota Cressida...

In my opinion, the two primary causes of noise in the M and Q series are the lack of double glazed glass and road noise from the wheel wells. I was at one time considering removing the doors, rear seats, and trunk lining, and adding Dynamat to all the surfaces. I have no doubt it would reduce the cabin noise, but it wouldn't do a thing to reduce the road noise from the wheel wells. I have seen some people spray an undercoating to the bottom and wheel wells and get great results, but we need to remove parts of the wheel wells to replace headlamp, etc. Mind you, I do not consider the noise in my cabin to be 'loud'. I just wish it were quieter. And I am a bit squeamish about dismantling the doors and removing lining as the various clips and retainers involved will likely be cheap and break, leaving me with a whole new issue. I decided to just leave it be and I am used to it now.

I agree its the door glass and wheel wells. I'm not sure about spending the 1600 and then finding that while it helped, its the doors. lol I have sound deadening already installed my a stereo shop in the doors...and when I actually listen, I think its coming thru the glass.

Mainly its the s*** roads in Dallas that transmit so much noise.

I have tried to find someone who can put it on a lift and then do Rhino (or similar) coating underneath...but noone here really wants to do it. :/ To me that is an inexpensive easy way to test it. If you look under the newer Q70's - they have strips of this semi-hard material with a felt like coating along the underneath outsides that I assume is to address some of the road the noise.

I'll just hang tight and do more research...again, it is not so much the 1600, but spending it and then it making little to no difference. That is a total waste.

My side windows and rear windscreen have the most (legal) tint and my windscreen has that colorless 3M coating that blocks most of the UV rays and a considerable amount of heat. I think by adding a high quality (legal strength) tint, I am at least slightly closer to true double glazed glass. Depending on your state laws, you might consider that for the windows. The wheel wells is another can of crap altogether.

I have a high quality tint all around as well...I have been looking to no avail for sound insulating tint. they make it for homes and office buildings but not for auto.

I decided yesterday to do the full cabin with sound deadening...the shop lowered the price to 1100...so why not.

It being done Monday so I'll report back after...

Results are in. So sound deadening the full interior, trunk, trunk lid, wheel wells, and doors did help. But there is still road noise - mainly tire roar. Even with new Pilot Sports. ARGH! Good news is that it is still a big, noticeable difference in noise reduction.

Now when just sitting it is really more vault like inside...it makes the interior feel so much better, richer almost.

My installer said with this car he thinks it is hollow portion where the body comes together where the door sills are. Its just hollow space which acts as a sound chamber. He has a foam Bentley's use in the same area that would fix it. I said I would drive it for a few weeks to see if that is what I wanted to do.

When I got home, in my usual fashion, I started thinking about it. I have sound deadening at my house...so I thought I would try something as an experiment. I installed the Aero kit side skirts on my car, and I remember there being a lot of extra space. So I popped one off to look at it. A super clean and easy place for sound deadening. I then cut sound deadening strips that are 7" wide and not so sure how long. I applied them from the line where the side skirt starts down and around the body. I did this for the entire length of the space front wheel to rear wheel well. Each side takes about 30 min - altho I'm good at this as I did the same side sills on my 15 Q70S.

I then did the other side.

Not surprising, but it cut the noise considerably. Its is much, much quieter. Now I can really tell the remaining noise comes from the cheap-ish side glass. My Audis have double paned acoustic glass all around...so when its not there you can tell. Not much I can do about that with spending 1500 for custom acoustic window film.

When under the car - there are shields on each side that go from front wheel well to rear wheel well. They are plastic with a bit of texturing. I don't remember these on my 15...but maybe I just didnt notice or don't remember. If they were not there on the 15 - then Infiniti added them to cut the road noise. If I had a lift - I would pop it up...remove them...and then use a spray rubberized coating which I'm certain would help even more. I may ask a local shop to rent a lift for an hour. Its such an easy project if you have the right tools. lol.

Just a recap for everyone.

You're going to great lengths on this. I commend you for it. Me? I just crank the music up lol.

I admit I'm a little obsessive. But for me the road noise was my main irritant with the car. I can deal with the old tech (especially coming from a 2016 S6 and my 2018 Audi Q7 with the digital dash, etc.) and long in the tooth styling (altho its still a beautiful design) as a trade for bulletproof reliability and ease of use. So it is nice that I am almost there with this project.

I love that with this car I can just drive it knowing there are so little other hassles, like with my Audis, previous BMWs and Mercs.

I hope Infiniti steps it up with the next version of the Q70 - as I would like to stay with the brand. I'm a little concerned as sedans are going away. And I don't love Infiniti SUVs. In hind sight I should have kept our 2016 QX70S we ditched for the Audi Q7.

I didn't think mine was that bad, of course it is already the quiet vehicle of the fleet. My Camaro is a race car, Yukon and Land Cruiser both have Magnaflow and big tires. That being said one thing I don't like is the hollow sound of the doors. I plan to sound deaden the doors only but maybe I'll try the wheel wells and other key spots. I probably won't do the entire interior but thanks for posting either way, good info.

Really appreciate this thread. Bookmarked!

Might I inquire what side skirts you found, and where could I find them? If a PM is necessary, I'd sure appreciate one. Thanks!

You can search Google for 2011-2014 M37/M56 Aero kit and then hunt thru the listings for best pricing, etc. I found the best price on Ebay here and it was my color code:

https://www.ebay.com/itm/G68E0-1MA2A-In ... 2749.l2649

The kit comes prepainted with your color code - so its a breeze. Only the side skirts fit for the refreshed versions...the Aero front does not for 15 and after. DO NOT PAY retail...these parts are years old and sitting in boxes with almost 0 demand. I also put the Aero kit from the FX on my 2016 QX70S - and the dealer wanted like 2900 and I shopped around and got it for half. But that kit is front, rear and sides and on a discontinued model.

They take about 20 min per side to install...but I've done it before so it might take a newbie a bit longer.

One note - these look great as they are more aggressive and stick out. But due to that...if you use an automated car wash with the roller bushes that are supposed to clean the wheels they will leave vertical scratches on the side sills. Touchless and handwashes or auto without the wheel brushes are fine.

Here is where the sound deadening went behind the side skirts - it wraps underneath a bit...can be stock or Aero skirts. This made a HUGE difference in road noise.

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1BlinkGone wrote: ↑

Fri Nov 30, 2018 10:39 am

Really appreciate this thread. Bookmarked!

Might I inquire what side skirts you found, and where could I find them? If a PM is necessary, I'd sure appreciate one. Thanks!

Thank you, parkstr8tr! Would like to see a pic of them on you car if possible. IMO this car is one of those great cars that the avg buyer just doesn't understand and it gets overlooked. That's ok as I gravitate to those things that aren't so popular anyways!

Follow-up....if you have no photos, thank you anyways. I don't intend to sound ungrateful for what you've submitted here already. This thread is VERY good. BTW, did you find any squeaks or rattles you didn't have before the installation of the sound deadening materials? I pucker at the thought of fasteners/pieces being broken and not holding tight later on.

Let me take some and post later today...no squeaks or rattles whatsoever. On the side sills - you can see I ran soudn deadening just under the where the clips go in - to avoid just what you mentioned.

Crappy pics but here you go...

parkstr8r wrote: ↑

Sun Dec 02, 2018 4:13 am

Let me take some and post later today...no squeaks or rattles whatsoever. On the side sills - you can see I ran soudn deadening just under the where the clips go in - to avoid just what you mentioned.

Thank you sir! Yes I see the sound deadening on the sills. Great car, bro!

Thank you OP for the informative information, I'm also like you in that I'm satisfied with the vehicle except for road noise.

So far I have changed new tires and added additional material to inside of the doors. The tires definitely reduces some road noise but since our doors already come from the factory with sound deadening on the outer layer the results from additional material inside doors was not very satisfying.

From you posts it seems that the biggest noise reduction came from adding sound deadening material inside the side sills.

What kind of sound deadening material did you use? From the photo it looks like a dynamat material that reduces the metal from resonating.

I also think the full interior helped in addition to the door sills. I can tell when sitting still its much quieter, and the Bose stereo also seems better. I think the shop that did the interior used the thickest dynomat or similar. I used a product called Noico in 80mm. My next and final addition will be to pull off the plastic shields underneath the car (they run from wheel to wheel on both sides) and place Noico there. I'm pretty sure that will get me to where I want to be.

I need a lift to do it tho...so when I'm having my 10mm extended stud spacers put on - I'm going to ask the shop to let me under there. lol Or just pay them to do it. There's several 10mm bolts on each shield so its super easy...you just have to be able to get under the car. If I had a lift its a 30-45 min job total.

props to you sir! MASSIVE PROPS! I love it when people find things to improve upon an already great car.