Writing this mostly as a journal for myself but hopefully it's useful for others. Others have posted about this as well which you can read about here: https://acurazine.com/forums/third-g...arning-980818/

I find the level of road noise on the RDX to be way too high for a "luxury" vehicle and got a quote from an audio shop that they could apply sound proofing to the floor and trunk for about $3500 over 3 days. That price is fair IMO except that their method only involves CLD (dampener) and no mass loaded vinyl which is where the real impact shows up so I decided to do it myself (To read more about the types of soundproofing see: https://resonixsoundsolutions.com/re...e-information/). I'm using Second Skin Audio for the 3rd time and ordered about $700 in materials and I expect to spend anywhere from 25-40 hours on it for the doors, floor, and trunk.

As a point of reference my noise readings before any changes on my local roads are:@60kph, average smooth road: ~63db
@100kph, fresh asphalt highway: ~63db
@120kph, fresh asphalt highway: ~65db
@120kph, coarse concrete highway: ~72db

Yesterday I started on the trunk which is pretty easy to take apart - including the subwoofer and the removable carpeting you could have it ready to go in under 30 mins even if you're not skilled - most of the parts are tight fitting and I learned a couple lessons about where to leave room. There's a bit of dampener on the floor of the trunk but the panels there are big echo chambers - tapping on it reveals a lot of hollow sounds and the trunk tray doesn't come with any sound insulation so the floor likely lets in a lot of sound. The panels that cover the wheel wells have a fair bit of fluffy padding intended to muffle noise from the wheel well while the very rear quarter panels have a thin (1/2") carpet in place. The rear quarter panel is very tinny and is another echo chamber but it's awkward shape means it's going to be tough to properly sound proof. There's lot of little holes and screws and bolts sticking out along with a lot of wiring harnesses which means getting 100% coverage of the space is not going to be realistic (100% is the goal for mass loaded vinyl). The wheel wells are also very awkwardly shaped so that I can't just drape a single piece of vinyl on top but at least they aren't tinny and seems pretty solid.

The last photo shows the closed cell foam that I'm using to separate the vinyl (didn't take a picture of the vinyl install). I worked for about 6 hours and only managed to get half the trunk down and had to reassemble things - the side panels were tricky to re-install and I should have paid more attention to how exactly they came out (I broke one clip and wore a couple ones out a bit). I think my plan now for the trunk is to just finish the floor as the rear quarter panel and wheel wells were just too labour intensive to be worthwhile (I've applied dampener on it already), I'd rather do a good job on the floor and move on to the doors and cabin floor. I hope to get all this done over the summer as I have a road trip to Seattle in late August and I-5 is a horrible, noisy highway to drive on. More updates as I get through the install.

 

Thanks for sharing! I admire the effort. Look forward to the before/after comparison.

 

Small sample size - while I've only done half the trunk my wife, who has remarkably sharp hearing, says that she's already noticed the difference. Says the trunk sounds less hollow and tinny - she didn't know what I did to it.

I've taken a couple days off next week to take the interior out so the real action happens then. I've learned that applying mass loaded vinyl is a much bigger job than just applying dampener so I'm not sure if 2 days is gonna be enough time for this. Fingers crossed.

 

How's the oem sound treatment on the doors? Have a couple box's of sound treatment just sitting in the closet. Been thinking about maybe putting them to use.

 

They're just hollow shells so you can make a nice impact if you add deadening in there. I'm hoping I can also put some mass loaded vinyl between the door and the door card but the fit might be too tight for that.

You can see photos of it in this thread: https://acurazine.com/forums/third-g...arning-980818/

 

Checked out the link, and wow. Figured it would have a little something on there for deadening. All bear metal. Now I'm definitely gonna do it. Thanks for the info 🤙

 

Anything that hold or trap water in the doors might not be the best idea🤔🤔🤔🤔😳😳😳😳😳😳😳😳😳
Like around the door beams, bottom to the door at the seams and drain holes.

The deadening on the floor plan from the factory is not hit and miss………....believe or not there’s actually a strategy.

 

Took a couple days off work to do the big job which is the main cabin. 5.5 hours today with a bit over 2 hours for taking out the interior and the remainder was to apply sound deadener and sound decoupler (closed cell foam).

Taking out the interior turned out to be surprisingly easy - other than a sticky bolt to release the passenger seatbelt everything else came right out with relative ease. The Torx screws for the seats require a T50 which will feel loose when you're using it but the next size is definitely too big. I chose to not take apart the centre console - didn't want to risk putting it together poorly.

Rear seat bottom was two latches and one screw - it was out in 10 mins (need to take out the rear cargo tray). All the plastic panels popped right out with no broken clips. The seats took a good 45 mins due to the seatbelt bolt being sticky - didn't want to screw that bolt up. It's possible to take the seat out by yourself especially if you're strong but it's an awkward manoeuvre especially on the driver's side, better to just ask for someone else to help you move it around. To get the carpet out you have two choices - you can cut some slits out as needed (around the rear seat bar and around the centre console) or you can take the silver bar and console out. I did the former - no one will ever see you cut the slits in. The carpet has some foam pieces on it and has a fair bit of padding - I'm surprised it doesn't work better than it does for sound deadening. This is also easier with a friend to take out. You do not need to be very handy to do this part, no need to fear.

I'm doing 3 layers in total and set a goal to not put on more than 70-80lbs of materials into the car which means I'm using less deadener than other people use - I felt that since there was already deadener that I could end up on the lower end of recommended coverage (~25%) and be fine. It's relatively easy to put in deadener and foam in the cabin - less holes to or awkward surfaces like in the trunk. I'm about 80% done with the foam today - I have about another hour of adding foam tomorrow before I do the hard stuff which is applying the mass loaded vinyl. MLV is where the real action is for sound treating a car - it's a sound blocker that weighs about a pound per square foot. It's a bit rigid, bulky, and to get the best results you ideally need 100% coverage of whatever you're covering - like no holes as sound knows where to find the holes.

My goal is isn't 100% coverage - I just don't have the time and energy - but this is where more careful workmanship from me will make a big difference so I expect this to take a good 10 hours just for the cabin.

 

Another 5 hours today and I've got about 75% of the vinyl in. While a bit laborious the vinyl wasn't too bad to work with - cuts easy and just need a bit of patience as you test each cut carefully lest you cut it up too much as each cut will let in more sound. I've chosen not to tape the vinyl down as it's pretty secure as is - will only tape pieces together as needed. Did a test fit of the carpet and it fits okay - will need to let it settle but there are no obvious issues with it. Just need to add vinyl over the rear seat bottom and the interior will be ready to go back in. I may or may not add foam to all the plastic trim - depends on time as I need to get the car back together by mid afternoon tomorrow.

 

The vinyls look badass! If all of these do not make your RDX as quiet as a Lexus, I would be surprised.

 

So I put things back together on Saturday after I finished putting some mats around the fuel tank area and taped down most sections of the mats to create a better seal. Reassembling the interior proved to be remarkably EASY - I think I had it back together after about an hour and in total I spent 16 hours handling the cabin area. If I were in better shape and the weather was cooler I think I could have done it in 12 hours to the same quality or just spent more time on getting the details right. I also took the time to add closed cell foam to all the plastic trim I reinstalled to help reduce vibrations. My goal wasn't for perfection as I have time constraints and I also don't want to add too much weight to the car.

I did hit a problem when the car wouldn't start - turns out having the battery disconnected for 2 days leads to bad things. I did have to get it towed to the dealer (for free) but the fix was simple - just a really hard push on the brake pedal during the start to trigger delivery mode. Next time I'll just reconnect the battery after taking out the seats.

How well does sound proofing work in the cabin? Traffic was too heavy today to test on the same roads I had done my original readings on but I was able to drive on a couple roads in similar conditions that I had anecdotal data on and it appears that I have knocked off 3-4db of sound at city speeds (from 63db to 59db at 60kph). I was consistently getting readings below 60db as I drove on city roads (with the sunroof shade closed). I expect a bigger difference at highway speeds particularly on rougher streets. A more scientific test will come next weekend. My wife also rode in the car and said she noticed a difference - her word was the car felt more "claustrophobic" being that it felt more isolated.

Still left to do:

• Half the trunk
• All four doors.

 

Finally got around to doing the doors this past week. The doors are a piece of cake to do - if you're just doing sound deadener then you can do each door in an hour easy (you'll need 4-8 sheets of deadener depending on how far you want to go with it), if you add sound blocker like I did then add about another hour to it (I didn't take any photos of the door with the sound blocker on it - sorry!). If you do sound blocker (MLV) you'll need 4 sheets for it - one for each door and you'll have lots of leftover to put in the trunk.

Adding dampener is super easy - the holes in the door are plenty large and the insides of the door are pretty flat with little to get in the way of things so I was able to use pretty large sheets of dampener. For the inner door skin I installed the dampener on the "outside" of the door so it would be hidden away. You could get away with just 1 sheet of dampener to get 25% coverage but I 'd recommend at least 1.5 sheets per door to get good coverage.

For sound blocker, you can start with a sheet measuring 24x36" and trim from there. I wasn't sure how much space the door had for it so was too conservative with the first one I did and trimmed more than I needed. In reality you can pretty much cover the whole door right to the edges and the door panel fits right over it. It was much easier to work with than I expected and if you're going into the doors I'd recommend you do this as well while you're in there. I don't quite have enough sound blocker to do the rear doors so I'll likely order a couple more sheets and do those when I get a chance - it'll just too easy to pass up and plenty effective. In total, the doors are a 1 day job (8-10 hours) if you do the whole thing and you don't need to be handy to do it. 2 sheets of dampener and a 24x36" sheet of MLV works out to about 8lbs added to the doors.

Results? I haven't road tested it with my sound meter yet but anecdotally it makes a nice difference - my comment to my wife was "It sounds like nothing is getting through the door anymore" and I noticed that I can turn up my sound system one extra notch b/c the audio is coming in cleaner/clearer.

I still have one more door to do, my trunk isn't complete yet, and I think I might have some remedial work to do on the floor (I was too conservative and was too concerned that the carpet wouldn't fit back in) - after that I can call it a day and can do some final road tests.

 

amazing work ! keep us updated on the results.

 

Re-opening this thread.

When removing the covers/seals for the holes to access the outer door skin, did you have to purchase new covers? I noticed on mine that the covers are attached with strong foam adhesive and deforms when removing it.

 

Did you ever get to repeat the noise level test on the same roads?