Sound Proofing Project-Phase 4: Firewall, Floor and rear speakers

[travisgarrison]

Phase 4: Firewall and floors
- Materials:
- 1/2" Closed Cell Foam (like Ensolite)
- 1/4" Closed Cell Foam (like Ensolite)
- Polyfil
- 92 Tack Spray Adhesive

- Tools:
- 10mm socket
- 12mm socket
- 14mm socket
- 8mm socket
- Socket Wrench
- Latex gloves
- box knife
- exacto knife
- measuring tape
- #2 Phillips screwdriver
- Flathead screwdriver

Goals: The total project should be under $100, under 50lbs, reduce road noise by 3-7dBA and eliminate rattles

Intro: Since the front wheel wells and road noise from the floor arguably generate the most combined noise in the car, this part of the project is absolutely essential. Almost half of the front wheel wells sit right against the firewall.

**This is an all day project and you won't be able to drive the car until it's done so keep that in mind when starting.

**Disclaimer: I am not responsible if you should damage your car in any way following these instructions. I am simply writing down what I did. If you should choose to mimic these instructions, you do so at your own risk.

Step 1: Prep
You will be pulling a lot of screws and pop-in plastic rivets. I highly recommend labeling sandwich baggies with locations and keeping things seperate. It will save you a lot of heartache.

The prep part of this phase is the most difficult and time consuming. Start by removing the glove box and center dash cover. You can remove the dash like I did to fix rattles but I won't cover that in this project since I found out it adds at least 2 hours to the project. I did fix my rattle though!

Remove the stereo head unit and then attack the seats. There are four bolts to each seat and you will need to remove the seatbelt bolt on the side of the seat.

Remove the plastic molding that covers the seatbelt assembly and the one that is on the bottom of the doorway. If you have rear speakers you will need to pull those. You will need to remove the covers over the emergency brake and the shifter boot.

next pull out the pop-in plastic rivets behind the seats that keep the carpeting in place. The storage net can be removed by carefully prying off the plastic covers (be careful, if you pry the wrong side they will break). Behind those plastic covers are small screws. Pull the carpeting covering the speakers and back panel... I just drape it over the back. I believe there are 8 10mm bolts that you will want to remove to get at the compartment to fill with poly-fil.

remove the carpeting which covers the floor and firewall. Rather than unbolt the center consol from the floor I recommend using your exacto knife to cut a slit in it to remove... it will be covered later by the shifter boot/cup holder.

once you get everything out, take a vaccum cleaner and remove all the dirt and grime. Wipe down the floor and firewall with a damp rag, then dry it.



Step 2: Firewall
Ok, now starting with the driver side firewall, place 1/2" closed cell foam all the way up. If you place a pillow on the seat beam and lay on your back you should have access to the firewall all the way up. Just like with the rest of the car, spray down the existing sound deadening material with the high tack adhesive then let it set for 5 minutes. Cut your foam in 6" strips, spray it with adhesive and fit it.

**There are two areas on the drivers side that you need to leave open. One is the 1" strip behind the clutch pedal. To find this, depress the clutch pedal to the firewall and then using your knife, cut out that strip so that the clutch pedal can be pushed all the way to the firewall. The second area is behind the gas pedal. Push the gas pedal to the floor and cut out a little block where it goes so that the gas pedal is not obstructed.

On the passenger side, cover the entire firewall except the black metal plate. Behind this is the Ecu and it should not be covered so that later someone can get access to it if need be.



Step 3: Center island and below the doors
Using 1/2" foam custom cut and place foam. You might note the position of the e-brake cover and cut a notch in the foam around this. It will allow the cover to sit properly. I had to put another screw into the front of this cover to get it to not obstruct the e-brake. Cover the sidewalls below the door panels with 1/2" foam as well.

**with any extra 1/2" foam you have I would recommend starting at the front floor and working your way back until you run out. If I hadn't run over my budget and did the project again, I would probably use 1" thick pad on the floors.

Step 4: floors
Apply 1/4" closed cell foam to the entire floor area. Do not cover the beam that the seats bolt onto. Start at the back 4" up the backwall and place the foam. On non-vertical sections you can save yourself adhesive by just spraying down the matting and immediately placing it rather than spraying both the floor and the matting.

Once you've worked yourself up to the firewall, use remaining foam to place a second layer on the floor. I ended up with a 1/2" layer everywhere and 3/4" in a few spots.



Step 5: Polyfil
Stuff poly-fil into the rear compartments until it starts spilling out. Then bolt up the two bottom corners of the aluminum backing and finish filling. Behind the passenger seat there is a plastic duct. Do not obstruct this. Its part of the ventilation system for the battery. Once you have enough poly-fil in there (I used a bag and a half), then bolt up the rest of the aluminum backing and reinstall rear speakers (if you have them).



Step 5: Put it all back together
OK, so just reverse the process that you used to uninstall everything. If you cut holes into the 1/2" foam where the plastic pop-in rivets go then it shouldn't be difficult to find them again.

Results:
OK, so of all the phases so far, I think that by far this has shown the best results. The car now sounds much much quieter during in town driving and significantly quieter on rough roads at highway speed. I would now compare the sound to most other cars I've owned rather than significantly louder. The polyfil behind the rear panel has now enhanced the crispness of the sound system. With all the sound deadening it now sounds like the music is all around me rather than localized. My major rattles are pretty much gone too.

Upcoming
- Phase 5: Rear wheel wells (postponed)

[E27006]

Please tell us about the water on the floor, how was the water entering the car and accumulating under the passenger seat location?

Have you traced and fixed the leak?


malcolm

[boogetyboogety]

Awesome. You must have the quietest Insight on the planet. I may have my next summer project in line now...

[travisgarrison]

The water on the floor wasn't from the outside of the vehicle. THe only way I know this is that it had a slight brown tinge like pop and a faint sweetener smell to it up close but not enough to reek up the whole car. My guess is that it was tea because the carpet above was not sticky like pop would make it. Anyway it most certainly came from the previous owner spilling something back there, which is cool because that showed me that the matting they put down doesn't mold.

Something to note about the sound deadening that I did is that the foam doesn't weigh much compared to some of the other products out there. Everything I put into the car combined weighs 17lbs. The result of that is that not many of the vibrations were reduced. The ones that were reduced were caused by the mat being between two objects that were vibrating.

Since our cars are aluminum framed and almost all plastic, it would take at least 100lbs of sound proofing mats (such as Dynamat) to get rid of a lot of the vibrations.

With that said, I'm willing to bet it's a great deal quieter than other Insights, but I can't scientifically measure that as I don't own a dBA meter and I am too cheap to spend the $22-30 bucks on a 'one-application' item. If someone wants to loan me theirs I'll gladly do that though and report the change.

[jf_cole]

Starting this and will continue over the next two weeks. I hope to improve the sound insulation, but it wont be as good, im still just using mousemats, I bought about 10 sqft of decent sound deadening materials and some wood floor underlay!

[jf_cole]

FINISHED!!!

Thank you for giving me the inspiration to attack this project. The car is SOOOO much quieter now and all i used was about €50 worth of decent sound deadening, a roll of wood floor underlay and mousemats!

I used the expensive stuff on the wheel arches and firewheel, with one layer of mousemat, the rest of the floor got two layers of mousemats. Then I topped it all of with one layer of the underlay.

I have been driving a Jazz for 3 weeks while I completed this at night, and I drove it work for the first time today, its quieter than the jazz now! I'm so happy it now.

I wish I had of done it quicker, the near 10 year old batteries werent feeling great afterwards.

Stereo also sounds better (bass from rear speakers are much improved) and doesnt need to be up as high.

[Cobb]

I am in the process of doing this to the new insight, but with spray on material. Ive used it on my past 2 scions and it makes the car noticable quieter on the highway.

I am just a little cautios about removing the rear plastic pieces because of the C pillar air bags.

Id love to drop the head liner and insulate that as well.

[travisgarrison]

I'm very unfamiliar with the new Insight so I really can't help you here. On the 1st generation insight the majority of the noise was coming from wheel wells, back compartment and firewall/floor. While doing sound dampening higher up would help, it isn't going to be as significant as those aforementioned areas... that's if the new Insights are similar to the old ones.

[pitviper33]

This is reviving a sort of old thread, but I didn't see any need to start a new thread and split up information on the same topic.

Travis or anyone else that did the modifications in this thread (or this series of threads), did you encounter any difficulty reinstalling the carpet after adding all that foam? It seems like you're really changing the shape of the bottom of the floor, so I'd expect the carpet to fit differently. Did you have to modify it any? Does anything look out of place once it's reassembled?

Also, did anyone find an inexpensive, commercially available foam that works well for this? I know Travis said he went to a specialty store, but I'm not sure I have anything similar near me. Is there anything in one of the big-box stores that would be equivalent? I plan to do some investigating, but I thought I'd see if any of you had already done so.

[travisgarrison]

Originally Posted by pitviper33

This is reviving a sort of old thread, but I didn't see any need to start a new thread and split up information on the same topic.

Travis or anyone else that did the modifications in this thread (or this series of threads), did you encounter any difficulty reinstalling the carpet after adding all that foam? It seems like you're really changing the shape of the bottom of the floor, so I'd expect the carpet to fit differently. Did you have to modify it any? Does anything look out of place once it's reassembled?

Also, did anyone find an inexpensive, commercially available foam that works well for this? I know Travis said he went to a specialty store, but I'm not sure I have anything similar near me. Is there anything in one of the big-box stores that would be equivalent? I plan to do some investigating, but I thought I'd see if any of you had already done so.

On the doors, near the pedals and on the sidewalls you need to be careful where you add material and how much. So for example, if you add material directly under where the gas pedal is then you won't be able to depress the gas to the floor and get full accelleration. This is the same with the clutch but not with brake pedal.

The general floor area is not a problem because reinstalling the carpet only has the seats that bolt back in. However anywhere panels or push rivets need to be reinstalled you just need to make sure you're careful not to put material around those contact points.

The specialty shop I went to was a rubber products distributor and I doubt they are that rare. The city I purchased them in is about 300k people so it's not like it was a major metro area. Someone else will need to chime in about something you could find in a walmart or a hardware store. Anything with a closed-cell foam will work. If you get open cell, not only will it not dampen sound well but it will absorb liquids and stink.