Sound Deadening Project

[johnloov]

Does anyone know how to remove the rear left and right trunk interior panels?

I'm dampening all doors, rear trunk, over the rear wheel fenders, and the front wheel well also. I noticed the rear wheel wells already have felt interiors.

The FL5 is damaging my hearing badly.

I'll update my findings.

I would really appreciate advice on this. Pics attached. Don't want to break any clips.

Best,

John

 

[Icehawk]

On the right side you need to remove the plastic piece the cover clips onto (there is a hidden screw under a small cover), the left side I assume is similar. From there you just gently pull it up. There are some videos on YT you can probably find that will help if you are unsure.

Bear in mind SPL might not change but the "quality" of the sound may (for the better).

 

[Miksfield]

I'm not sure about the FL5 but on my DE5, wrapping the rear cargo cover with some felt/velvet type material helped. I don't think it changed the loudness, but it muffled the sounds coming from the trunk area.

 

[johnloov]

On the right side you need to remove the plastic piece the cover clips onto (there is a hidden screw under a small cover), the left side I assume is similar. From there you just gently pull it up. There are some videos on YT you can probably find that will help if you are unsure.

Bear in mind SPL might not change but the "quality" of the sound may (for the better).

I removed this clip and the screw I'm pointing at here. Is that the one you are referring to? Then I just pull up? Thanks

 

[johnloov]

Today I will complete dampening the doors.

I'm going to use Amazon basic deadener, and a variety of other acoustic materials.

 

[Icehawk]

I removed this clip and the screw I'm pointing at here. Is that the one you are referring to? Then I just pull up? Thanks

I believe so, I only removed the right side to access the subwoofer but I doubt it's much different. Just go slow and gently!

 

[johnloov]

And so it begins, the journey to murder unwanted noise and a migraine.

 

[tibwolf]

Finished a large chunk of what I wanted to do. Got everything treated and finally got some rudimentary measurements.

The rear doors went about the same as the front. These had a fiber/plastic barrier which was more like other vehicles instead of the neoprene layer in the front.

The outer door skin has much more usable surface area for applying CLD than the front. I used two sqft here and .75sqft on the plastic door cards. Here I used the last of my SM200L thinsulate in two layers similar to the front doors. I also used some butyl rope along the crash bar and the door joints. Of note, the OEM butyl along the vapor barrier is just... nasty sticky stuff. My arms were covered by the time I was finished.

The rear hatch area was pretty simple. I used 6 total sqft of CLD which I forgot to take pictures of, but expertly reproduced with green shapes.

I moved to the back hatch and stuffed it with some of the thicker SM600L thinsulate. Consider working carefully or wearing gloves if you want to manipulate things here. Lots of sharp plastic to cut up your hands with.

I applied the thicker thinsulate to the hatch area and then reassembled the trim pieces.

No adhesive used, but for some of the vertical pieces I slightly wedged corners under wiring harnesses to keep things in place. The only thing that didn't fit flush is the spare tire storage foam. It's raised around .5"-1" because of the foam, so the cargo tray piece is slightly raised in the middle section. Not a big deal.

I tried to capture the change in overall SPL while driving. Here, I found a stretch of road I could consistently test on but temperatures and humidity were slightly off. These measurements were on cruise control at 40mph in 4th gear with no fan. Ignore that the readings are interpreted as 106db... I measured an overall 1db lower level, but didn't grab individual frequencies. A lot of the lower frequency rumbles remain but higher frequency tire and wind noise was cut significantly. Engine noise was unaffected, which probably contributed to the overall levels as well.

Conclusion: Sound treatment is just about finished. Driving is less fatiguing as a lot of the higher frequency sounds have been muted. Lower frequency sounds such as road imperfections and bumps largely remain. The MP4S tires still make odd resonant sounds at certain RPMs, but overall tire noise has been reduced.

I spent about an hour driving around highways in my area. Wind and road noise are better than my previously treated Sierra 1500. Rough road surfaces, potholes, and expansion joints still give you audible feedback. MP4S tires still have weird resonance at certain speeds. The engine sounds kind of weird in the absence of loud driving noises. I have a PRL HVI installed with the OEM exhaust.


Running totals are:

	CLD	Thinsulate
Front fender liners (per side)	1.5 sqft Dynamat Xtreme	4 sqft
Front doors (per side)	3 sqft Resonix Mega CLD	10 sqft
Rear doors (per side)	2.75 sqft Resonix Mega CLD	8 sqft
Hatch door	0	6 sqft
Hatch interior	6 sqft Resonix Mega CLD	30 sqft

Bonus! I tried fitting an SI SQL 12 series 2 subwoofer where the OEM unit was. This driver is 7" deep. If you create a fiberglass enclosure to fit flush at the wheel well, I think you'll be okay with any driver that is 6" deep. You'll need to trim the carpet, but you will only lose about 2" of space.

 

[johnloov]

I went over kill with the doors, fully covered the interior doors with dampening and also acoustic closed seal foam. I’m at about 83-86 decibels on the highway at 65mph. Peak 89. Still hear those p4s resonating noise through the cabin.

 

[TopazM3]

Nice work! Are you an acoustic/sound engineer?

 

[johnloov]

Finished a large chunk of what I wanted to do. Got everything treated and finally got some rudimentary measurements.

The rear doors went about the same as the front. These had a fiber/plastic barrier which was more like other vehicles instead of the neoprene layer in the front.

The outer door skin has much more usable surface area for applying CLD than the front. I used two sqft here and .75sqft on the plastic door cards. Here I used the last of my SM200L thinsulate in two layers similar to the front doors. I also used some butyl rope along the crash bar and the door joints. Of note, the OEM butyl along the vapor barrier is just... nasty sticky stuff. My arms were covered by the time I was finished.

The rear hatch area was pretty simple. I used 6 total sqft of CLD which I forgot to take pictures of, but expertly reproduced with green shapes.

I moved to the back hatch and stuffed it with some of the thicker SM600L thinsulate. Consider working carefully or wearing gloves if you want to manipulate things here. Lots of sharp plastic to cut up your hands with.

I applied the thicker thinsulate to the hatch area and then reassembled the trim pieces.

No adhesive used, but for some of the vertical pieces I slightly wedged corners under wiring harnesses to keep things in place. The only thing that didn't fit flush is the spare tire storage foam. It's raised around .5"-1" because of the foam, so the cargo tray piece is slightly raised in the middle section. Not a big deal.

I tried to capture the change in overall SPL while driving. Here, I found a stretch of road I could consistently test on but temperatures and humidity were slightly off. These measurements were on cruise control at 40mph in 4th gear with no fan. Ignore that the readings are interpreted as 106db... I measured an overall 1db lower level, but didn't grab individual frequencies. A lot of the lower frequency rumbles remain but higher frequency tire and wind noise was cut significantly. Engine noise was unaffected, which probably contributed to the overall levels as well.

Conclusion: Sound treatment is just about finished. Driving is less fatiguing as a lot of the higher frequency sounds have been muted. Lower frequency sounds such as road imperfections and bumps largely remain. The MP4S tires still make odd resonant sounds at certain RPMs, but overall tire noise has been reduced.


Running totals are:

	CLD	Thinsulate
Front fender liners (per side)	1.5 sqft Dynamat Xtreme	4 sqft
Front doors (per side)	3 sqft Resonix Mega CLD	10 sqft
Rear doors (per side)	2.75 sqft Resonix Mega CLD	8 sqft
Hatch door	0	6 sqft
Hatch interior	6 sqft Resonix Mega CLD	30 sqft

Bonus! I tried fitting an SI SQL 12 series 2 subwoofer where the OEM unit was. This driver is 7" deep. If you create a fiberglass enclosure to fit flush at the wheel well, I think you'll be okay with any driver that is 6" deep. You'll need to trim the carpet, but you will only lose about 2" of space.

Hey, how did you get the rear trunk subwoofer panel off?

Nice work! Are you an acoustic/sound engineer?

I did way too much research online ) I am an electrical computer science engineer.

 

[johnloov]

I spoke to several audio shops in the Bay Area here and the top two told me the same thing. The front wheel wells are not inside the cabin, it’s the doors and rear wheel wells you need to address. Also the both said… no offense, the honda civic is a tin can, you would be better selling it, getting a Mercedes or bmw…. They had done entirely stripped honda civics, and only gotten them to honda accord decibels. I’m still going to try.. Many YouTube’rs are claiming you need to dampen the front wheel arches, but that’s only going to remove rock noise hitting the inside wall mostly. I took a look at my wife’s Mercedes Eqe (66-67db -at 80mph one of the top 5 quietest suvs) and it also has plastic wheel wells in front and velvet in the rear, just like the civic. The big difference the Mercedes deployed several sound dampeners right by the rear tire well.
After the overkill on the doors, I was driving and when I leaned forward, I didn’t get the same noise resonating, which means the front tires are not the problem. When I leaned back, the howling and resonance of the rear tires were reverberating the entire rear, This is what’s next! Absolutely eliminate the noise around the rear wheel wells.

 

[tibwolf]

Hey, how did you get the rear trunk subwoofer panel off?

Looks like you got it, but for anybody else wondering, I took off the rear seat side trim at the C pillar, similar to what you'd remove for changing the ADS module. I then removed the plastic trim around the hatch latch. On the silver floor mounted mounting rings you can pry the plastic at the base of the ring to reveal either a screw or a bolt and undo them to remove the folding tray. Next you have some bolts behind the airbag writing on the C pillar trim. Finally you have another set of bolts about halfway up the side trims near where it meets the rear seats.

Remove those things and undo some of the weather stripping and you can remove the final lower rear trim pieces which cover the subwoofer and the opposing side.

The front wheel wells are not inside the cabin, it’s the doors and rear wheel wells you need to address. Also the both said… no offense, the honda civic is a tin can, you would be better selling it, getting a Mercedes or bmw…. They had done entirely stripped honda civics, and only gotten them to honda accord decibels. I’m still going to try.. Many YouTube’rs are claiming you need to dampen the front wheel arches, but that’s only going to remove rock noise hitting the inside wall mostly. I took a look at my wife’s Mercedes Eqe (66-67db -at 80mph one of the top 5 quietest suvs) and it also has plastic wheel wells in front and velvet in the rear, just like the civic. The big difference the Mercedes deployed several sound dampeners right by the rear tire well.

I disagree with the shops input. Plenty of people on diymobileaudio have applied sound treatments to the front wheel wells and fenders with positive results. I myself have as well. It doesn't just cut down on rock noise, it cuts down on any sound waves from the tire hitting your road surfaces which hit the wheel well area.

I still have 2.5sqft of CLD left and a ton of thick thinsulate so I may tackle the rear wheel wells if I ever get around to jacking up the rear of the car.

 

[johnloov]

Sounds good, I’ll try wheel wells next. Send pics of where you dampened.

 

[johnloov]

Does anyone know, can I cover these holes up and seal them up??