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Thread: How not to install MLV

  1. #11
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    the thing to worry about is the glue. good glue, as much contact surface area you can get and you are good to go.

    You are gonna get a few posts below this one potentially explaining why the weight needs to be suspended between a foam layer, but that's the way it's supposed to be. steel/foam/vinyl.

  2. #12
    gyroscopes and infrared FoxForce's Avatar
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    The point of the foam is to decouple the barrier (MLV) away from the resonant surface. A barrier is only as good as it's resonant frequency. Gluing MLV to a stiff surface makes it stiffer thereby increasing it's RF. Floating it keeps it limp and decreases its RF and increases its ability to block road noise (RF 50 - 250 hz).

    I have a floating barrier similar to what's pictured (could be the exact same thing) on my outer door skin on my rear doors. Went in in two pieces, one above and below the horizontal crash/support beam. Glued down with construction adhesive. It was a little tricky, but not impossible. Been there for years, hasn't moved AFAIK, and I live in the a weather extreme climate (95*F in the summer -30* in the winter).

    Again, if the barrier on the outer skin failed, start over and do it right.....or put it (or something else) on the inner skin. Think outside the box for materials. I don't think velcro is a good idea, but then I've never tried it in such a manner.
    Last edited by FoxForce; 03-29-2011 at 01:40 PM.

  3. #13
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    Quote Originally Posted by earthtodan View Post
    Interesting. Don recommends industrial strength Velcro, which I bought on Amazon. What would you suggest instead?
    I really have to make that clearer - the "Industrial" part of the name refers to the hook and loop. The PSA on the stuff you buy other places is not the same at all. It will not hold on vinyl and doesn't have the heat tolerance you need in a car. I noticed somebody somewhere posting that people could either buy it from me or from Amazon. I thought it would be petty to correct him, but several other people have had the same problem.

  4. #14
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    Now that I've read through the entire thread, I'll add a little bit more. I've got sheet metal / CCF / MLV on both the inner and outer door skins. Extra CCF on the inner skin between the MLV and the trim panel. Even though there are small breaks in the inner skin coverage:

    It's actually blocking more noise than the barrier on the outer skin. At least in this car there is an amazing amount of noise entering inside the outer skin - top, bottom and sides. If you have speakers mounted to the inner skin, the MLV will acoustically reinforce the baffle.

    Here's the secret:

    It's really important to fit the MLV before you attach the CCF. The Velcro makes this easy because you can make small adjustments in registration and because you can easily peel it off and lay it in the trim panel as you go along. I'd guess it took 20-30 test fittings to get the trim panel to fit back on in its original position with the MLV in place.

    DO NOT GLUE ANYTHING TO YOUR SHEET METAL! There's no reason to do it. Yes I've done it and yes I started this project by first removing 6 layers of crap from every surface in the car. What happens if you get a ding in your door? What happens if it's completely someone else's fault? Insurance will pay for the body work needed to repair it. They won't pay for the time required to make it possible to do that simple repair. PDR is out. Welding a dent puller to the skin is out. All of that stuff needs to be cleaned off first. It's probably going to be less expensive to replace the skin and you'll pay the difference in either case.

  5. #15
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    Thanks Rudeboy for the photos and explanation.

    How were you able to get the door to fit back on? Many of us would never be able to get a factory fit from a door like that. Even though I see the panel poppers hollowed out on the piece you made there, on many of our doors the fit and finish between the metal and card is far too close to achieve the level of coverage you have here.

    Is it worth going through lengths this far if the coverage will not exceed, say, 80%?

    Some of us don't want door cards that are bulging beyond the ability of the card to fit properly.

  6. #16
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    Quote Originally Posted by Whiterabbit View Post
    Thanks Rudeboy for the photos and explanation.

    How were you able to get the door to fit back on? Many of us would never be able to get a factory fit from a door like that. Even though I see the panel poppers hollowed out on the piece you made there, on many of our doors the fit and finish between the metal and card is far too close to achieve the level of coverage you have here.

    Is it worth going through lengths this far if the coverage will not exceed, say, 80%?

    Some of us don't want door cards that are bulging beyond the ability of the card to fit properly.
    The door card fit back on in its original position. when I was done, there was a considerable amount of 1/4" CCF on the side of the MLV facing the trim panel. A few things are critical. The first is that you put holes in the MLV for the clips that are large enough to for the shoulders of the clips to pass through and make contact with the inner skin. The other is that you have to be really patient. Having done this on many cars now and having watched as others did it, what gets cut away is usually not what is in the way.

    I use the trim panel as a template to do a rough cut of the MLV. Turn it over and fill the hollow areas with crumpled paper or something to make it fairly flat. Lay the MLV in the trim panel an trim the edges of the MLV to fit inside. I do this with the clips removed. Put the clips back in and press the MLV down on them to mark their spots - stretching the MLV turns it whit. Cut small holes so just the points of the tips show through. Now you have references for registration. Follow the same process to cut openings for the things that will need to pass through and contact the sheet metal.

    Move the MLV to the door and hang it with Velcro, using the clip holes for alignment. Enlarge the holes to exactly match clip receptor holes. Take the MLV back to the trim panel and cut the clip holes so the clip can pass all the way through. You may have to accommodate the little towers the clips sit on. Every manufacturer is different, so you'll have to improvise, but if some part of the trim panel made contact with the inner skin, you have to let it pass through.

    Rehang the MLV and test fit the trim panel. Before you cut MLV, slide a piece of paper between it and the trim panel to be absolutely certain you have correctly identified the obstruction. To five you an idea of how precise this has to be, I built access hole covers out of fiberglass. The were held in place by self tapping screws with heads that are about 1/8" thick. In a few spots I had to cut tiny holes in the MLV for the screw heads.

    It really is a huge pain in the ass, but when the trim panel finally seats, it is great.

    I don't know how much you lose with 80% coverage. Some doors have steel brackets through which the panel screws fit. Cutting the MLV behind a heavy steel structure like that shouldn't hurt. I've been in Mustang doors that had a much denser vapor barrier than we usually see. It's pretty clearly there for noise and it covers a lot less than 80%. Limited coverage at the inner skin probably makes covering the outer skin more important.

    Some cars really won't let you do anything on the inner skin. BMW's have an elaborate barrier already that is very convoluted and mates tightly with the trim panel. It also mitigates the need for another barrier. Newer Mazdas, Minis and some VW's have removable inner skin inserts that also make this tough.

  7. #17
    Founding Member earthtodan's Avatar
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    There are enough surfaces on my Audi door skins that contact the metal that after cutting away about 25% of the surface area I decided it would be ineffective to do it that way.

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