Soundproofing (Or Dampening/Absorbing/Blocking)

[iSOBigD]

Hey guys, let me start off by saying that hyundaitechinfo.com is not free as mentioned in some other posts, so I'm hoping I can get some help with the following:

- Removing door panels
- Removing the felt material at the top inside the trunk (under the sub)
- Removing roof liner to get to the bare metal

If anyone has tips or links, please let me know!

Background:
I find the Genesis is a great car and very quiet, but it could be better. Compared to my Maxima, it has quieter glass and the aerodynamics/plastic/felt bits help a lot, however it still has more road noise (which I'm sure the tires have a lot to do with) and exhaust noise. I checked and the trunk basically had 0 soundproofing and dampening materials and this is likely the case for most of the car, so I feel like there's room to improve here. Since the nice design means no visible bolts/nuts/screws in most places and I couldn't find any videos or instructions on how to get to the door metal, subwoofer, roof and floor without guessing my way around and breaking things, I figured I'd ask here. I did see one crazy 600+ pic soundproofing job on a Genesis but I didn't see how he actually removed the covers to get to the metal.

What I did so far:
After obsessing about cheap soundproofing and learning about it for a month: In the trunk (bottom and lid), I ended up using some Dynamat style material for vibration absorption (Covered the middle of any large flat area that vibrated easily) then foam over and around the spare wheel to absorb sound, then a layer or MLV to block sound (Covers the same area as the default trunk felt liner). It worked very well, it killed any echo in there, ate up some vibration when I turned up the music, and it made it so I hear my engine a lot more than my exhaust when I floor it. (I love the way the V6 sounds, but I used to hear the exhaust at the back of the car a lot better than the engine right in front of me which made no sense for a big sedan)

^^ I cut the sound blocking material to the shape of the trunk and added foam under it since this pic.

^^ There are hollow areas I could fill up with foam but I didn't find much sound really ends up in there nor does it vibrate that much so I didn't spend much time on this.

What I would like to do:
- Same thing to the doors (at least MLV as I hear they're padded nicely already), floor, roof, wheel wells and under the floor mats if doing the entire floor is too complicated.

 

[BrazGenesis]

Quite impressive!
My car is a leasing., Otherwise I would do at least what you did.
How do you rate the effectiveness of it so far?

 

[Rey]

With all due respect to Dynomax, it is expensive.
For years now and with several cars, including Genesis and Equus, I have used a cheap alternative, which in my opinion, is not materially lesser than Dynomax. It is aluminum coated butyl rubbber household rain gutter repair tape, found in roofing sections of Lowes and Home Depot for about $16 a roll. Each roll is about six inches wide and 25 feet long. Once applied, it really sticks. For instance installed it on a trunk lid of a black car - sun, heat, etc has not loosened its grip.

 

[iSOBigD]

With all due respect to Dynomax, it is expensive.
For years now and with several cars, including Genesis and Equus, I have used a cheap alternative [...]

Absolutely, and after lots of research I did the same thing. Unfortunately, finding these cheap products (as well as MLV) is really tough in Canada so I had to get it online and get MLV shipped to a US Home Depot then drive there, etc. It was a hassle but still a fraction of what composites and dynamat would cost.

Quite impressive!
My car is a leasing., Otherwise I would do at least what you did.
How do you rate the effectiveness of it so far?

Thanks! Unfortunately it's hard to measure these things since every car is unique and so is every application, and I didn't do DB measurements before/after.

From an unscientific point of view, I got rid of some rattle around the subwoofer during some songs with hard kicks so I have 0 rattle now at the same volume. I also went from hearing the exhaust a lot when revving the engine to hearing the engine only. That's not to say it muted the exhaust, but from the driver's seat it overwhelms the exhaust sound instead of the opposite.

I got exactly what I expected and I paid $50 Canadian in total for the materials, and I still have about half a roll of the roofing stuff. I also ordered MLV and acoustic foam for another $100 for about 100 square feet so overall it's cheap not counting the work you put in and I should have enough to do the roof, doors and floor if I wanted. Things like Dynamat just to dampen some vibration would cost 200-400$ for enough to cover maybe the trunk.

Now I still would need some help removing the door covers if anyone's familiar with how that's done.

 

[iSOBigD]

So I watched some guys pull out the fender covers in the trunk and under the car as well as the sides of the carpets (during rustproofing)... It looks like with some dash/trim removal tools and a basic screwdriver it's pretty easy to pop everything off.

However, I noticed bolts covered by plastic caps under the car seats - can anyone confirm if removing 4 of those per seat is enough to lift it up and work under it? I got some days off next week so I want to add more foam and MLV and make this the quietest Genesis around.

 

[BrazGenesis]

I had something of the kind done in my cars in Brazil.
The progress I got from floor treatment was so modest that it was hard to tell.
The trunk, however, responded very well in the road noise area.
I did not use expanding foam at all. (but definitely like the idea)
Just a car vibration deadener (not the expensive brand - but automotive) and a plastic foam with closed bubbles (aiming to create a sealed air barrier) (looks like a thick light carpet)
I fact I starting giving up with the difficulty to improve the engine firewall deadening and (shame on me) a thorough work on the doors.
Please keep reporting your progress.

 

[iSOBigD]

Thanks for sharing! I'll be working on it this week and get as much as I can done with pictures.

I know that if you only use closed cell foam and vibration absorbing material you probably won't hear much of a change (except less rattle if you had any) because there's no material to block or absorb/dissipate sound yet. I plan on replacing the CCF with acoustic foam wherever possible and also adding mass loaded vinyl, so we'll see how it turns out.

For now the only testing I did was having my phone play music and putting a layer of foam or MLV on top to see is it lowers the volume and it did.

 

[iSOBigD]

Alright, big update on the way. I worked on the floor under the front seats (I'll post those later) and the rear seats/bench.

Rear Bench
Tools needed: Size 12 socket wrench (x2 screws)

The rear bench takes just a few minutes to remove and I attached pictures including the tools I used. There are 2 screws in total behind the left and right seats.

- Remove both by sliding the tool between the bottom and back rest parts and be careful not to scratch anything. (4 more screws hold the back rest part in case you need to remove that too)

- Pull up on the front edge of the bench but don't pull it out completely! (It's held in by 2 clips that slide in and out)

- Detach the power cables (x2 on each side) by squeezing one side and pulling it out. (I'm assuming these are for heated seats so cars without that feature may not have these)

- Bench removed. Notice the stock vibration dampening material in black. I'm not sure what it is, but it's very hard like plastic. This is also used in parts of the trunk near the fenders and near the firewall. The edges of the panels don't vibrate at all as they're attached to the car frame (near the sides and rear of the seat) so I left those alone.

- Added some vibration dampening material. I made sure not to cover wires and removable parts.

- I pressed the acoustic foam against the surface and drew lines where I needed to cut off parts.

- To cut the MLV, I just put the foam over it, drew outlines and cut along them.

- Foam cut to fit around any bolts, holes, wires

- Put foam then MLV in the car, it fit pretty well. I tried to cut them enough to not be visible once the seat goes back in.

- Seat back on looking stock. The only issue I ran into is the right side of the seat popping up a bit because the clip doesn't hold it down very well. I'll need to compress the foam a little more around that area so it stays in place perfectly. Right now we have metal, acoustic foam, MLV, the stock foam under the seat and the seat itself to block sound so this should be one of the hardest areas for sound to penetrate. I didn't do the back rest area because I sound proofed the trunk so I'm not sure it would make any noticeable difference.

 

[iSOBigD]

For the rear, I found removing the entire carpet was a lot of work and I would end up covering the same area as the rear carpets did, so I just pulled out the carpets and cut foam and MLV to match. This ended up covering the entire rear floor and up to the vents under the front seats.

 

[iSOBigD]

Since I had so much acoustic foam, I decided to revisit the trunk as it was a little lumpy due to the thick memory foam I had used originally.

I ended up stuffing thick (3") memory foam around the walls / spare tire, then cut acoustic foam and MLV to match the trunk liner. It ended up looking stock while keeping the trunk super quiet.

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[iSOBigD]

I had spare memory foam so I basically filled up space like this around the tire to cut down on exhaust noise:

The fenders were hollow and sounded it too, so I decided to work on them as well. Getting to the fenders:

I used some Vibration Absorption material on the large flat areas (on both sides) then put memory and acoustic foam to fill up the space between the fender and trunk liner. This absolutely killed echo inside there and made it sound like you're knocking on wood if you knock from the outside. (Due to the thick foam pressing against the fender)

The right side has less room due to more wiring being there, so I had to be careful not to damage anything or have foam rub against weak wires. I used 2 layers of acoustic foam as the memory foam was too thick to go all the way around that box.

Right now I have no foam in the trunk lid, but if I play music on my phone at max volume and close the trunk, I almost can't hear anything. I also had my phone record audio from the trunk while I played music around the car on a second phone to check for weak spots...From the sides (fenders) it's almost impossible to hear anything. The weakest/loudest point is now the license plate area where you could hear a bit of music, but it's literally 10-20x louder once I open the trunk.

 

[RN2X]

Did it help?

 

[iSOBigD]

Did it help?

Absolutely. By far the loudest parts of my car now are the engine and windows.

This is how I would recommend or rank soundproofing on a Genesis Sedan:

1. Middle Column (exhaust) (Hard difficulty, left it alone)
- Hyundai did a great job of using CCF + MLV across the middle of the car, front to back, cut to match the shapes and curves. Under both front and rear seats they also have minimum of 1+ inches of some sort of foam. (Similar to hard memory foam) so I didn't bother adding anything to this area. Remove these materials only if you want a super loud car...

2. Trunk Floor (Easy difficulty)
- This reduces exhaust noise noticeably. You will mainly hear the engine when revving it, not the exhaust, which is a big change.
- It helps slightly with road noise, though that's not the main thing you'll notice.
- No noticeable effect on music quality/rattle as this is under the subwoofer. I thought killing trunk echo may have affected bass quality at first, but then I realized I had a lower bitrate version of some songs. At ~320k they sounded the same.
- If you have rattle, it can be the subwoofer cover or window shade. (I plan on putting foam or rubberized material between the cover and speaker)

3. Driver/Front Passenger Floor + Firewall (Medium difficulty)
- This is a bit harder to get to, the driver's side has the pedal you need to remove, the seats have to come out (I just leaned them onto the rear seats) and space is tight
- Mainly you will hear the window noise more than usual due to less sound coming from under you.
- It makes a difference in road noise but not so much in terms of the engine. The firewall already has a lot of material from Hyundai between you and the engine.

4. Rear Seats + Floor (Easy difficulty)
- Adding Acoustic Foam + MLV under the seats and behind the seats separates them from the trunk and fenders quite a bit so it helps with overall road noise and especially exhaust noise coming into the cabin.

5. Doors (Medium difficulty)
- The doors each have 2-3 screws but there are multiple wires and speakers to cut the foam/MLV around as well as having limited space
- I have not done these yet but already I find the windows to be noticeably louder than the doors, so they do a good job of blocking sound already. When I get around to it I will add a layer of acoustic foam in there and report back.

Overall, the thing you notice most is any weak point. I hear engine sound from my vents and road noise from my windows above all else. If I'm parked, the second I close the door I hear nothing except loud trucks. It's hard to measure the exact results as I couldn't drive and record in the same exact conditions, but that is the main result of all this. I have no problem whispering to my girlfriend in the passenger seat but if I crack open a window the noise level goes up 100x.

All of these changes also help with sound quality overall because less sound escapes the car and there is about 0 echo. This may not matter to people, but basically with the windows up, others won't hear your music much. Lastly, my goal wasn't to fix any rattles because I only have some around the Sub at times, but adding vibration material on any panels likely to vibrate can't hurt and they do feel/sound nicer if you knock on them.

 

[srobak]

Excellent tutorials. Thanks for doing this!

I have one question though....


Dafuq is this splatter?

 

[iSOBigD]

Oh, all that crap is grease from the rustproofing I had done on it. They sprayed every bolt and metal edge inside and out of the car, so I actually had to wipe it off the surfaces I glued stuff to. It doesn't look pretty, but it's all hidden away and it should help in case salt and water get in there.

You may think it's overkill but to give you an idea, here's what I found while doing my floor around the front seats (This was not visible without removing the Genesis name sills):

All that white stuff is dry salt on and around the carpet, right next to the bare metal of the car, so in a couple of years that can easily rust the underside. I went all over and cleaned up the salt before re-assembling things.

 

[iSOBigD]

Genesis Front Seat Removal

This was easier than I expected, and I had to do it just to pull/roll up the floor carpet in front of the car. I left the power connected as I just needed to lean the seats back to pull up the carpet. I'll post instructions for that later.

 

[iSOBigD]

Removing Name Sills (To detach the carpet)

- Use trim removal tool or your hands to pull up about 1-2 inches. The side closest to the front of the car needs to be pulled out horizontally (away from the frame).
- Remove corner piece as well (1 screw then pull out and to the left, away from the fender)
- This applies to both front left and right sides. The left side just has one more screw for the hood release handle.

 

[OneFunGenesis]

This is awesome. I am going to grab some peel n seal from Lowes and go at my trunk and back seats soon. This has helped immensely though...thank you

 

[iSOBigD]

Carpet Removal

 

[iSOBigD]

This is awesome. I am going to grab some peel n seal from Lowes and go at my trunk and back seats soon. This has helped immensely though...thank you

My pleasure. I'll post everything I did in case people search for this stuff in the future. Just remember Peel n Seal helps with vibration/rattle but you'll need some acoustic foam or thin closed cell foam + MLV for noise reduction.