My lightweight sound deadening project

+ Reply to Thread
Results 1 to 25 of 25

Thread: My lightweight sound deadening project

  1. #1
    SupraForums Member warranty's Avatar
    Join Date
    Nov 2003
    Location
    Silicon Valley, CA
    Posts
    159

    My lightweight sound deadening project

    It all started after I took apart my front doors to install the 6.5" speakers (documented in this thread). Having insulated the door by dampening the front door metal skins with Second Skin Audio damplifier CLD's, lining the interior door panel with 1/4" thick closed-cell foam (to diffuse the sound), and adding another 1/8" thick closed-cell foam in between to further diffuse/block sound, it then became very obvious the majority of remaining noise came from the rear wheel well/fender area. I could clearly identify tire roar/road noise as coming from the rear wheelwell area at highway speeds (it's as if the rear speakers are playing these noises). As somebody theorized, the rubber rear brake duct (which runs inside the rear fenders and is completely uninsulated so it's acting like a "horn") is probably a major source of road noise so I went about quieting that area down.

    Actually, I believe the wheel arches themselves are dampened relatively well from the factory: on top of the interior wheel arches Toyota engineers added a second metal sheet on which the wire harnesses are clipped/secured, and foam is sandwiched in the space between this sheet and the actual wheel arch to dampen vibration. I added some damplifier CLD tiles on the actual brake duct itself, on the outer fender skin, and on top of the wheel arch just inside the fenders. You can see those black-faced CLD's in this picture:



    Once that's done I stuffed the area immediately surrounding the brake duct and on top of the "outside" wheel arch with fiberglass wool insulation material (from Home Depot), some of which you can also see in the above picture (the yellow stuff is the fiberglass wool). I also completely stuffed the lower part of the B pillars with fiberglass wool since the Toyota engineers had already stuffed a little bit of foam material there:



    Once that's done I cut a piece of mass-loaded vinyl (MLV) sheet to completely cover up the outer wheel arch and the brake duct to act as a noise barrier since MLV weighs about 1 lb per square foot. Basically, it's MLV sitting on top of fiberglass batten sitting on top of the wheel arch. This you can see in this next picture (the black shiny stuff you see is MLV):



    You can also see in the above picture that I covered the access hole at the bottom of the B-pillar with black 1/8" thick closed cell foam.

    BTW my 93.5 hardtop doesn't originally come with those braces/gussets that triangulate the B-pillar to the floor (which are apparently standard on targa tops), but some of the mounting holes are already drilled/tapped on the floor. I had to enlarge/drill 3 more holes (2 on the B-pillar and 1 on the door sill), installed M8 nutserts (rivet nuts), and installed those braces which I had bought from a parted out Supra. Along with the mass-loaded vinyl sheet that I cut, I'm only adding about 3 lbs on each side of the car with those braces so I figure it's a very small weight penalty to pay for some additional chassis stiffness.



    Pictures of the nutserts I installed, at the bottom of the B-pillar:

    Nutsert on the door sill:


    Again, I lined all the interior plastic panels (rear quarter window surround & rear speaker surround) with 1/4" thick closed cell foam to diffuse sound, and adding 1/8" thick closed cell foam whereever I could sandwich them in between the body and the interior panel.

    Finally, before I put all the interior panels back I added another layer of 1" thick cotton-based duct insulation (I found this stuff at Lowe's: Frost King "no itch" natural cotton duct insulation), which has a reinforced aluminum foil back, with the fabric side facing "outside" to muffle/diffuse whatever noise that's still getting through. I chose natural cotton insulation for this so if little fibers got loose they wouldn't cause itches/allergic reactions or other undesirable health side effects. I didn't take any good pictures but here's a picture of what this duct insulation looks like (the roll I got is wider than this):



    I used exactly 15ft of this stuff, completely lining the entire rear perimeter wall of the car (from B-pillar back to the rear hatch sides to the trunk, and then back to the other side of the car to the opposite B-pillar). I also stuffed the rear fenders BEHIND the wheel arches with more fiberglass wool (sorry, no pictures, but I did have to remove the power antenna and the fuel pump ECU to get my hands in there), and I covered up the driver side rear fender access hole (where the fuel pump ECU is mounted) with 1/8" thick closed cell foam.



    It's worth noting that the metal panel just above the muffler is made of very thin gauge steel (Toyota engineers were saving weight so they obviously used the thinnest possible gauge steel where structural integrity isn't needed), so I added some damplifier CLD to dampen it, and on top of that I added another piece of MLV to help block the noise from the muffler. (This you can also see in the picture above)

    So, what's the verdict with all that stuff I did?

    Well, it all worked, VERY WELL I think. Whereas previously I could clearly identify tire roar/road noise broadcast from the rear wheelwell area, that noise source is now completely gone, replaced by just the "general background noise" that doesn't seem to come from any particular direction (note that I didn't do anything on the trunk floor). In fact, I *think* I can identify road noises from the front wheelwell area now, so that's an area I plan to tackle next.

    Since my goal is to add sound deadening where they are most effective and not go completely crazy with adding weight indiscriminantly, how much weight did I add to the car? About 13.5lb so far. Here's my estimate:

    - About 4.5lb of Second Skin Audio damplifier CLD sheets (3 lb of which went towards dampening the front door skins)
    - About 2lb of fiberglass wool insulation (about 3 rolls of this material) that got stuffed into the rear fenders/brake duct area
    - ~3 lbs total: mass loaded vinyl. I used MLV to cover the area just above the rear muffler and the outside wheel arches.
    - About 1lb of foil-backed cotton duct insulation for the rear perimeter wall of the car
    - About 3lb of various 1/4" thick and 1/8" thick closed cell foam (front door and interior door panels)

    The car is obviously still not as quiet as a Lexus (without adding some major weight) but all that work I've done has made quite a noticeable improvement with not much weight penalty, which is easily offset by the 20lb rear seat back that I removed. (I kept the rear lower seat cushion--which weighs only about 10 lbs).

    When I have some time I think I'll go tackle the front wheel wells. I'm hoping I can cut that noise down while adding about 4~5lb of weight--we'll see if that's possible...
    Last edited by warranty; 04-10-2012 at 11:30 AM.

    1993.5 6MT hardtop, hybrid GT28Rs
    2008 6MT M3 sedan (DD)

  2. Remove Advertisements
    SupraForums.com
    Advertisements
     

  3. #2
    SupraForums Member
    Join Date
    May 2007
    Location
    Rolla, MO
    Age
    42
    Posts
    4,988
    ^^^ nice write-up. Thx for sharing with the community.


    Craig
    Government cannot give anything to anybody that it doesn't first take from somebody else. Whenever somebody receives something without working for it, somebody else has to work for it without receiving. The worst thing that can happen to a nation is for half of the people to get the idea they don't have to work because somebody else will work for them, and the other half to get the idea that it does no good to work because they don't get to enjoy the fruits of their labor.
    - Adrian Rogers

  4. #3
    SF Contributing Member Tayousei's Avatar
    Join Date
    Jun 2009
    Location
    Winnipeg, Canada
    Posts
    2,082
    Nice write up. I added , cld tiles, ccf and mlv to all accessible interior surfaces so far except the roof, including door panels. Makes a huge difference. Im not sure fiberglass is a good idea because its harmful to inhale ive heard. I used roxul batting and others use cotton.
    1994 Supra, 3.25L Stroker, BW S363, ProEFI, Titan S2 trans/stall, OS Giken LSD, S1 cams fully built by Eden (me.) - 636RWHP @ 20PSI on E70
    My Build Thread


    www.TheraVape.net
    www.facebook.com/theravapeinc

  5. #4
    SupraForums Member
    Join Date
    Dec 2011
    Location
    NW
    Posts
    169
    Nice work. I'd love to see some decibel sound numbers but too bad you didn't record those before upgrading.

  6. #5
    SupraForums Member warranty's Avatar
    Join Date
    Nov 2003
    Location
    Silicon Valley, CA
    Posts
    159
    Yeah, believe me, I thought long and hard before adding the fiberglass battens, but (1) compared to cotton they're less likely to grow mold in places that "could" be exposed to moisture, and (2) in my installation they're all covered up with closed-cell foam sheets, MLV, and the interior panels. These are the same material we have in our homes (in walls, attics, etc.) so I think as long as they're "properly installed" it's no more "dangerous" than living in our own homes.

    I think fiberglass is primarily an irritant (causes skin itches and sneezing, etc.) more than anything else, according to people who worked in environmental safety committees of processing plants of those fiberglass material, so I think as long as we don't leave it carelessly exposed it's probably okay. I thought about Roxul but I didn't want to get an entire gigantic pack for the little amount that I needed.

  7. #6
    From the land down under Mr Ree NZ's Avatar
    Join Date
    May 2008
    Location
    Wellington, New Zealand, 6023
    Age
    40
    Posts
    2,809
    As a precaution, just be sure to use a mask and gloves when working with it to avoid inhaling the glass fibres, and getting itchy forearms.
    1996.8 JDM SZ JZA80 NA-T 310RWKW

  8. #7
    SF Contributing Member Tayousei's Avatar
    Join Date
    Jun 2009
    Location
    Winnipeg, Canada
    Posts
    2,082
    Lol yeah i ended up giving the leftover roxul away i think or garbaged it. It was a lot wasted thats for sure. I also stuffed the whole back area under my subwoofer floor with it. When you do this extensive a job, you can be parked beside an active lawn mower and not hear it. Also i can crank my sub up and you cant hear a thing outside my car. No vibrations to the exterior

  9. #8
    Stock Twins King Stu Hagen's Avatar
    Join Date
    Jan 2002
    Location
    Kirkland, Wa.
    Posts
    3,959
    ha ha so doing instrument cluster stuff wasnt enough "fun" huh~! Jeesh... the love for the supra! Nice work. BTW.....I am going to attach a link to another member here that had done an extensive job doing this and recorded sound savings and weight gains. I kept the link cause I really wanted to do this as well. Even though it added like 250#s or something.

    http://www.supraforums.com/forum/sho...pening-Project

    (PS: You never got back on the LED boards)

    stu

  10. #9
    SF Contributing Member Tayousei's Avatar
    Join Date
    Jun 2009
    Location
    Winnipeg, Canada
    Posts
    2,082
    Stu, I haven't put the new Zener (spelling?) diode in yet. My car is in pieces undergoing a complete upgrade to 3.2L single and body :P I still have it in the package but I fully intend to install the new diode you sent me once the car is about to go for paint and tune. I will for sure update you and haven't forgotten As for price and weight from my own sound deadening job, it must have added at least 100lbs, cost about 1000$ in materials, but definitely worth it for a street car.

  11. #10
    SupraForums Member warranty's Avatar
    Join Date
    Nov 2003
    Location
    Silicon Valley, CA
    Posts
    159
    Heh believe it or not I'm a step ahead of you. With some el-cheapo decibel meter I bought on fleaBay (it measures in dBC, not dBA) I measured 97dB @ 70mph, 67dB @ idle a while ago...long before I did these insulations. (Just for reference, right now in the quietness of my room I'm getting ~58dB so don't try to compare the numbers to what you read in magazines..it's the relative numbers that matter)

    When I get a chance I'll drive around with this decibel meter and report back the new decibel readings...

    Quote Originally Posted by D.Rated View Post
    Nice work. I'd love to see some decibel sound numbers but too bad you didn't record those before upgrading.

  12. #11
    SupraForums Member
    Join Date
    Oct 2003
    Location
    Hawaii
    Posts
    464
    I read some of the new features of the '97 model is the added sound dampening in the rear of the car including some sort of cover over the the rear quarter panel opening near the side duct? interesting.
    Attached Images

  13. #12
    From the land down under Mr Ree NZ's Avatar
    Join Date
    May 2008
    Location
    Wellington, New Zealand, 6023
    Age
    40
    Posts
    2,809
    Quote Originally Posted by green_banana View Post
    I read some of the new features of the '97 model is the added sound dampening in the rear of the car including some sort of cover over the the rear quarter panel opening near the side duct? interesting.
    I can confirm this for you. Mine is a Series 2 chassis and it has all of the sound dampening material, and the flexible plastic quarter panel covers too.

  14. #13
    SupraForums Member warranty's Avatar
    Join Date
    Nov 2003
    Location
    Silicon Valley, CA
    Posts
    159
    Any chance you could take a picture of what the plastic cover under the A pillar looks like? I know all the electrical junction/fuse boxes are there, so I'm kind of curious what the Toyota engineers actually covered.

  15. #14
    SupraForums Member
    Join Date
    Oct 2003
    Location
    Hawaii
    Posts
    464
    maybe if the ideas behind the revised sound dampening the Toyota engineers came up with on the '97 chassis could be applied to the '93-'96 chassis instead of haphazardly adding unnecessary sound dampening material to the entire car. I'm sure they studied the car in detail to see where improvements could be made. I like the idea of quieting the interior sound levels of the car but with the minimal amount of sound dampening material.

  16. #15
    From the land down under Mr Ree NZ's Avatar
    Join Date
    May 2008
    Location
    Wellington, New Zealand, 6023
    Age
    40
    Posts
    2,809
    Quote Originally Posted by warranty View Post
    Any chance you could take a picture of what the plastic cover under the A pillar looks like? I know all the electrical junction/fuse boxes are there, so I'm kind of curious what the Toyota engineers actually covered.
    I havent had the kick panels off for a long time, but next time Im where my car sleeps, Ill pop it off and snap a pic for you.

  17. #16
    SupraForums Member
    Join Date
    Nov 2004
    Location
    Union City, CA
    Posts
    610
    I wonder if there is a noticeable audible difference between 93-96 interior and 97-98 because of the new featured sound deadening and insulation materials

  18. #17
    From the land down under Mr Ree NZ's Avatar
    Join Date
    May 2008
    Location
    Wellington, New Zealand, 6023
    Age
    40
    Posts
    2,809
    It would be very marginal, but the improvement would only be noticeable with a DB meter I expect.

  19. #18
    SupraForums Member am527's Avatar
    Join Date
    Jun 2011
    Location
    Redondo Beach, CA
    Age
    30
    Posts
    526
    Quote Originally Posted by shenofjo View Post
    I wonder if there is a noticeable audible difference between 93-96 interior and 97-98 because of the new featured sound deadening and insulation materials
    I've sat in a few 93-96, and own a 97. I cant really tell the difference. My 97 feels pretty noisy on the highway at high speeds, but I'm used to an is300 DD which is VERY quiet.

    I definitely agree that the wheel wells and brake ducts are probably the spots where you'll be able to deaden the most sound. The brake ducts especially funnel the air sound like a microphone, and you can hear it if you have no music on.
    1997 Supra Turbo - Undergoing Build

  20. #19
    SupraForums Member
    Join Date
    Oct 2003
    Location
    Hawaii
    Posts
    464
    maybe covering up the side vents would reduce road/wind noise. I think the vents are more form than function. if anything the vents cool my tires more than the rear brakes. after pulling most of the plastic panels in the rear when I replaced my hatch struts got me thinking of gluing some closed cell foam insulation to the inside of plastic panels and butyl rubber sound deadening material to the metal areas near the rear wheel well. not sure about using the fiberglass insulation inside the car where the fibers could get airborne from constant wind and vibration. not expecting my car to be lexus quiet but something is better than nothing for under $200 and less than 50lbs of added weight. I already added some sound deadening material to the door skin and noticed a little noise reduction.

  21. #20
    SupraForums Member
    Join Date
    Oct 2003
    Location
    Hawaii
    Posts
    464
    I just read that neoprene foam makes a good sound barrier at a cost of approx $5/sq ft for a 1/4" thick sheet. this might work as a good sound barrier behind all the plastic panels in the hatch area.

  22. #21
    Im A Fuking Ninja!!! TonyN's Avatar
    Join Date
    Dec 2007
    Location
    Tucson
    Posts
    4,550
    Quote Originally Posted by green_banana View Post
    maybe covering up the side vents would reduce road/wind noise..

    Nope, I have the Do-Luck side with the deleted duct and its still noisy
    *94 MKIV / SP63 / ATF Stage 3 Auto / FTI 3.5k Converter / CCW SP500 / Meth/Pump 91 = Garage Anchor

    06 W203 6 Speed Manual / Black on Black / stuff = Daily Driver




    More pictures here: http://www.supraforums.com/forum/sho...yN-Version-2.0

    Condition Trumps Mileage: http://www.supraforums.com/forum/sho...dition+mileage

  23. #22
    SupraForums Member warranty's Avatar
    Join Date
    Nov 2003
    Location
    Silicon Valley, CA
    Posts
    159
    Well, just to add my update to this thread, recently I went to a local carpet store and bought 2 x 3 yards of fibrous carpet padding (about 1/8" thick, compressed fiber with a thin plastic backing) and laid a single layer (with a lot of cutting/trimming) on the entire back half of the car: trunk, interior rear quarter area, rear seat cushion and "waterfall" area. The thing doesn't weigh very much (it's 20oz per square yard so the entire piece was only 7.5 lbs, while I used about 6 lbs. of it) and on top of what I've already done it basically muffled the entire rear section of my car. Now it's very clear that road noise is coming from the front wheels and, of course, windows/windshield. I think what I'll do next is to use that carpet padding stuff to line the area under the front seats and front footwell, which shouldn't take more than another 3~4 lbs. of material. This stuff works (trying sticking your cellphone under this padding and hear the ringtone set at the loudest setting), and it's cheap (the guy charged me $5 per linear yard, so in total I spent around $20) and lightweight.

    Don't get the compressed foam carpet padding (they are too thick and isn't "airtight")--make sure you get the fibrous type, which looks like gray mouse hair. If you lift up the carpeting of a modern luxury vehicle I think you'll find a lot of the same carpet padding (aka "carpet jute") stuff, and I think the top of the line Lexus LS460 will also have the mass-loaded vinyl layer which starts to make things REALLY heavy since they are about a pound per suqare FOOT.

    I also filled the bottom of the front A-pillar cavity (the hole allows access to the door wiring grommet) with some window-mounted AC insulation foam from Home Depot (they're chunky and thick but easily compressed so it's perfect for the job), and covered it all up with some 1/8" closed-cell foam sheets. I think this accomplishes the same thing as what Toyota engineers did in the 97+ cars. Weighs next to nothing at a cost of $2~$3 per side.

    All in all, considering I added around 13.5+6 = 19.5 lbs total, I'm pretty happy with the results.

    Quote Originally Posted by green_banana View Post
    I just read that neoprene foam makes a good sound barrier at a cost of approx $5/sq ft for a 1/4" thick sheet. this might work as a good sound barrier behind all the plastic panels in the hatch area.
    Last edited by warranty; 05-24-2012 at 06:19 PM.

  24. #23
    SupraForums Member
    Join Date
    Nov 2004
    Location
    Union City, CA
    Posts
    610
    any further decrease in decibel readings? a simple picture of the rear with where you put the padding would be great! thanks

  25. #24
    SupraForums Member warranty's Avatar
    Join Date
    Nov 2003
    Location
    Silicon Valley, CA
    Posts
    159
    You know, the el-cheapo Scosche SPL1000 db meter I bought on fleabay didn't register any meaningful reduction at 70mph (it reads around 97~98dB max before and after, according to my notes, with a lot of fluctuation), and I think that's a dBC, not a dBA as typically quoted in car magazines. However, I can definitely tell you that I can now no longer identify any noise as specifically coming from the rear or rear tires (there's always some ambient noise, of course). Now it's almost as if I have two kick-panel speakers broadcasting mid/high-frequency noises from the front tires, and that's what I intend to address next: dampening the plastic front wheel liner (it probably acts as a big drum) and using some fibrous carpet padding in the front foot wells.

    The Toyota engineers already added asphalt dampening sheets on the floor so I don't think I'll add any more unnecessary weight there (besides, it's easy to add if I really think it's necessary).

    Pics: I'll post some later.

  26. #25
    SupraForums Member kane93tt's Avatar
    Join Date
    Sep 2010
    Location
    QC, Canada
    Posts
    858
    Blog Entries
    1
    Another trick to sound proof is to use glad plastic bag inside cavity and to gently fill them with urethane foam. Don't add too much or it will overexpand and can do body damage. Urethane don't trap moisture like fiberglass wool and won't make you scratch yourself all the time if some particle goes inside the car !

    It's also mroe easy to work with and cost less.

    I used the urethane trick in 2 cars we installed audio in and when doing the Surpa it's on the list with the tar and foam sound proofing from eDEAD Audio

+ Reply to Thread

Similar Threads

  1. Sound Deadening????
    By 1A1 in forum Exterior , Interior, and Detailing
    Replies: 9
    Last Post: 12-11-2010, 11:05 PM
  2. Sound Deadening????
    By 1A1 in forum Mobile Electronics (I.C.E.) and Lighting
    Replies: 11
    Last Post: 12-08-2010, 09:24 PM
  3. Sound deadening material - what's best?
    By TurboMatt in forum Mobile Electronics (I.C.E.) and Lighting
    Replies: 20
    Last Post: 08-03-2009, 10:10 PM
  4. Sound deadening spray?
    By ScrewDrvr in forum Mobile Electronics (I.C.E.) and Lighting
    Replies: 10
    Last Post: 11-25-2003, 07:52 PM
  5. sound deadening
    By mk3fold in forum MKIII (1986.5-1992)
    Replies: 2
    Last Post: 03-22-2003, 02:39 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts