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Thread: Sound dampening material FATMAT installation in my XJ

  1. #1
    behemothxj Guest

    Sound dampening material FATMAT installation in my XJ

    Over the years of upgrading my Jeep to the bigger and better parts has been a learning curve to see what parts work better than others.

    This is my daily driver, and the quirks have made me become neurotic. Now that I have installed a RockKrawler front and rear longarm setup, I have eliminated all of the bushings in the suspension, and now have heim joints. I have 23 of 24 suspension points that are heim. With that all connected directly to my unibody has amplified the vibrations.

    The list of new parts I have installed to eliminate the vibes is extensive. And yet they were only a sliver of the problem.
    As of right now I have replaced:
    1)Both Driveshafts
    2)T/case
    3)Both axles with all new bearings (Completely different problems)Ball joints
    4)New Fox shocks installed
    5)New MTR/K 35s
    6)New rims (to eliminate the possibility of being bent.. and unbalancing the tires)
    But all of the issues are not old worn out parts, it is the harmonics of ALL of these parts spinning above 60mph together into a tin can(My XJ)I know it is like an empty soda can.
    Plus a DB meter at 65mph peaks at 92db (even with the carpet inside)
    I spend 4 days researching what to buy... And due to the cost, and amount I chose FATMAT..(It is made here in the USA).<--- always a plus!!!
    On Ebay, I bought 100square feet of 80 mil material. Dynamat was 3 times more expensive

    Here is the before and after photos.

    Amazing how much dirt creeps below all of the carpet.


    Here is the floor started.



    Last edited by behemothxj; 02-02-2011 at 06:02 PM. Reason: Because this web page doesnt have spellcheck... But needs it.

  2. #2
    behemothxj Guest

    Re: Sound dampening material FATMAT installation in my XJ

    The doors were easier. But I chose to cover the outer skin, and inner panel as well.



  3. #3
    behemothxj Guest

    Re: Sound dampening material FATMAT installation in my XJ


    Here is the floor. You can see how little of factory dampening material there is. I would guess that the factory stuff is 35 mils.
    I doubled the transmission tunnel, and tripled up on the sections where your feet go.




    Last edited by behemothxj; 02-02-2011 at 07:37 PM.

  4. #4
    behemothxj Guest

    Re: Sound dampening material FATMAT installation in my XJ

    Now here is why Cherokees are not good long term vehicles. I KNEW this long ago, but I like the body style. This problem is exagerated because I have coilovers in the rear of my XJ. Here is my suspension. And since I shortened the stress points into the body, I have accelerated the stress in the weak point.

    This is the crack in the sheet metal below the rear seat. This is bigger that any other XJ I have seen so far.




  5. #5
    Join Date
    Jan 2006
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    Chandler
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    1,337

    Re: Sound dampening material FATMAT installation in my XJ

    So are you happy with the resuts? Roughly what was the cost?

  6. #6
    behemothxj Guest

    Re: Sound dampening material FATMAT installation in my XJ

    Here is the Roof. I had to buy 25 square MORE to cover the top. I bought (by mistake) 50 mil pads. Between the spars, I doubled up the Fatmat above the front two of the three sections. 50 mil has no markings.


  7. #7
    behemothxj Guest

    Re: Sound dampening material FATMAT installation in my XJ

    I even did the front fenders, and under the hood. I used a total of 125 square feet total inside of the XJ. The shipping weight was 47 lbs.
    And I spent
    $160 for 100 sq ft of 80 mil
    $ 44 for 25 sq ft of 50 mil
    This has made the biggest difference in my Jeep.
    The doors sound more solid when shutting the doors.
    The harmonic is almost completely gone.
    The Db meter at 65mph only reached 82.5 db (And you can actually talk without yelling when the windows are down.
    The speakers have better sound,and more bass (because when you seal the door, you are creating an almost semi sealed enclosure)
    The engine is quieter from what I put under the hood.

    I hope this will also insulate the sheet metal during the summer sun. The black Jeep is a dutch oven that bakes you like a potato.
    But this has been the best money I have EVER spent on comfort. I highly recommend that you come and go for a drive to hear the difference for yourself. I will let you be the judge on the improvement.

    Here is a selfish pile of the latest "Posed photos" YES, there is 2 quarts of Armor-ALL Haha
    Last edited by behemothxj; 02-04-2011 at 02:54 PM.

  8. #8
    Join Date
    Jan 2008
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    Prescott Valley
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    545

    Re: Sound dampening material FATMAT installation in my XJ

    Nice write-up. I don't have as modified XJ as you but I have the harmonics issue. It drives me crazy. I've spent a lot of money and time trying to figure out the harmonics I get above 60 but nothing has helped.

    I may have to do this to mine next....
    99 XJ, 33s GY MTR, RK LA Kit

  9. #9
    Join Date
    Jan 2008
    Location
    Prescott Valley
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    545

    Re: Sound dampening material FATMAT installation in my XJ

    I have done some reading and a lot of peeps are saying that Peel and Seal is basically the same material as Dynamat. In your research what did you determine? Peel and Seal is cheap and if you get the right stuff there is no smell.
    99 XJ, 33s GY MTR, RK LA Kit

  10. #10
    behemothxj Guest

    Re: Sound dampening material FATMAT installation in my XJ

    I disagree with the no smell issue. Peel and seal is made to go on roofs, and what the YOUTUBE videos say,is that is is the same. NOT QUITE!!! The adhesion on peel and seal is not as good as the stuff I usedI do not know how well it would stick to vertical panels(doors) Or the ceiling.Fat mat has a pressure sensitive backing and I almost COULD NOT REMOVE a piece once I used the roller to press it on. It took both hands to pull up a 5 inch by 5 inch piece.
    Peel and seal using 125 SQ feet would make your Jeep wreak something fierce compared to what I used. Fat mat had a slight odor out of the package... but does not smell after 3 days inside the Jeep.

    Don't get me wrong, but if you are going to spend a few thousand bucks on tires,long arms, gears, shocks, and ALL of the little parts to make an awesome Jeep. I wouldnt skimp on this product just to save a few bucks.

    Dynamat is.067 thick,36 sq feet $145 (WAY TOO EXPENSIVE and thinner)
    Fatmat .080 I paid 100 sq feet $160(Ebay 12/10)
    Fatmat .050 I paid 25 sq feet $44 (Ebay 12/10)
    Peel and seal if roofing material sold at home depot) 20 sq feet I guess is around $20(But you get what you pay for)

  11. #11
    behemothxj Guest

    Re: Sound dampening material FATMAT installation in my XJ

    You can do an entire Cherokee with 100 sq feet. I just went overboard using 125 sq feet.
    You could do an entire Wrangler with 50 sq feet and have extra left over.
    I would guess a JK would take around 100 sq feet as well.

  12. #12
    Join Date
    Jan 2008
    Location
    Prescott Valley
    Posts
    545

    Re: Sound dampening material FATMAT installation in my XJ

    Good insight. I have never really taken a whiff of the peel and seal but your point is good. $160 is pretty cheap to do the whole vehicle. I think I will tackle this sometime.

    Thanks again.
    99 XJ, 33s GY MTR, RK LA Kit

  13. #13
    Join Date
    Sep 2009
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    Phoenix
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    114

    Re: Sound dampening material FATMAT installation in my XJ

    Keep us posted about the thermal difference inside. I'm planning on using something like this to insulate the firewalls on the Wranglers. I sweat it's the heat transfer from the engine bay that melts my A/C controls on the TJ.

  14. #14
    behemothxj Guest

    Re: Sound dampening material FATMAT installation in my XJ

    There is a thermal difference already. When I run the heat in the winter as I'm out in the desert at night, and turn off the Jeep, the cab will retain the warmth longer.The concept is no different than your house. I cant wait to see how much better the AC will be in the summer.

    Think of the concept of cast poured walls that are insulated. It keeps the heat out, and then the AC only has to cool the interior space... Not the heat generated from the outside.


    I had an older, 89 Cherokee, It had no carpet. AND I HATED how it would be like a furnace. On the Wrangler, I suggest that you do the floor, and firewall. Make sure you use the 80 mil stuff. I was disapointed with the 50 mil product.

    I dont think you will need any more than 50 square feet to do the entire inside of the Wrangler from firewall to rear taillights

  15. #15
    Join Date
    Oct 2010
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    Re: Sound dampening material FATMAT installation in my XJ

    Quote Originally Posted by behemothxj View Post
    There is a thermal difference already. When I run the heat in the winter as I'm out in the desert at night, and turn off the Jeep, the cab will retain the warmth longer.The concept is no different than your house. I cant wait to see how much better the AC will be in the summer.

    Think of the concept of cast poured walls that are insulated. It keeps the heat out, and then the AC only has to cool the interior space... Not the heat generated from the outside.


    I had an older, 89 Cherokee, It had no carpet. AND I HATED how it would be like a furnace. On the Wrangler, I suggest that you do the floor, and firewall. Make sure you use the 80 mil stuff. I was disapointed with the 50 mil product.

    I dont think you will need any more than 50 square feet to do the entire inside of the Wrangler from firewall to rear taillights
    I might like to use some of that! I have no A/C so I just take my roof off, but still...

    bsns. Just got srs.

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