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Thread: Fiberglass scoop on Metal hood

  1. #1
    Join Date
    Jan 2011
    Location
    Sonoma, California
    Posts
    2

    Default Fiberglass scoop on Metal hood

    Does any one have any good tips and instructions on mounting a fiberglass hood scoop onto a metal hood. I have tried 3M 8115 Panel Bond and the expansion/contraction rates of that material sandwiched between fiberglass and metal caused cracking and ghost lines. The car is black so it get's hot. Is the Dura Bond any better than the other products and if so, what are the actual stages of successfully using this product to mount the scoop? The local paint shop is of little help as they recommended the 3M 8115 Panel Bond and now they say that the 8115 cannot be outside of the actual margin of the scoop and then fiberglass has to go around the seam, then short strand fiberglass bondo, then flexible poly bondo. By the time I get all of that crap on, the hood will be above my windshield. I would appreciate some real advice here please. Thanks. Thomas Little Wolf (Littlewolf1109@aol.com)

  2. #2
    Join Date
    Nov 2005
    Posts
    27,115

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    Quote Originally Posted by Little wolf View Post
    Does any one have any good tips and instructions on mounting a fiberglass hood scoop onto a metal hood. I have tried 3M 8115 Panel Bond and the expansion/contraction rates of that material sandwiched between fiberglass and metal caused cracking and ghost lines. The car is black so it get's hot. Is the Dura Bond any better than the other products and if so, what are the actual stages of successfully using this product to mount the scoop? The local paint shop is of little help as they recommended the 3M 8115 Panel Bond and now they say that the 8115 cannot be outside of the actual margin of the scoop and then fiberglass has to go around the seam, then short strand fiberglass bondo, then flexible poly bondo. By the time I get all of that crap on, the hood will be above my windshield. I would appreciate some real advice here please. Thanks. Thomas Little Wolf (Littlewolf1109@aol.com)
    Everything used to bond, fill and coat the metal/fiberglass seam need to be flexible to prevent cracking. The hood scoop is tricky because it's in a place that gets hot from underneath and also take the full blast from the sun. With any products you can get a "read through line" in extreme temperatures but using the proper stuff you should not get cracking.

    We trace the scoop onto the hood and grind the metal where the hood and the scoop come together and we also grind the edge of the scoop. We sit the scoop where we want it then drill holes about every 3 or 4 inches around the scoop and screw it down to the hood. We then remove the scoop and apply the Dyna-Weld to both the hood and scoop by pressing it into the grinding scratches. Put the two panels together and tighten the screws enough so that the DW starts to creep out but not so tight that it all pushes out because the DW is where the strength of the bond is between scoop and hood. Allow the DW to harden.

    After hardening remove the screws and counter sink the holes and also grind off the edge of the seam so that you have a somewhat blending of one surface to the other. Mix more DW and apply it around the seam and in the screw holes by pressing your first pass in then building on top. Allow the DW to harden.

    You can grind or sand the DW so that it creats a good transition then apply a flexible filler/putty to finsh the leveling job. Once your filler work is complete spray a flexible filler primer, guide coat and block sand. Once you're happy with the prep work apply your top coat but realize that ANY hardened paint like single stage urethane or clear coat need to have a flex additive to help stop if from cracking.

    If you want this to look good for a long time use high quality products. Don't buy cheap paint because it usually won't stay flexible as it ages.


    The next one of these jobs that I do I'm going to try Fusor Cross Bonding Adhesive to bond the glass to the metal but I would probably still use the Dyna-Weld to finish the job because the Fusor is not a filler product it's a glue.


  3. #3
    Join Date
    Jan 2011
    Location
    Sonoma, California
    Posts
    2

    Default

    Quote Originally Posted by Len View Post
    Everything used to bond, fill and coat the metal/fiberglass seam need to be flexible to prevent cracking. The hood scoop is tricky because it's in a place that gets hot from underneath and also take the full blast from the sun. With any products you can get a "read through line" in extreme temperatures but using the proper stuff you should not get cracking.

    We trace the scoop onto the hood and grind the metal where the hood and the scoop come together and we also grind the edge of the scoop. We sit the scoop where we want it then drill holes about every 3 or 4 inches around the scoop and screw it down to the hood. We then remove the scoop and apply the Dyna-Weld to both the hood and scoop by pressing it into the grinding scratches. Put the two panels together and tighten the screws enough so that the DW starts to creep out but not so tight that it all pushes out because the DW is where the strength of the bond is between scoop and hood. Allow the DW to harden.

    After hardening remove the screws and counter sink the holes and also grind off the edge of the seam so that you have a somewhat blending of one surface to the other. Mix more DW and apply it around the seam and in the screw holes by pressing your first pass in then building on top. Allow the DW to harden.

    You can grind or sand the DW so that it creats a good transition then apply a flexible filler/putty to finsh the leveling job. Once your filler work is complete spray a flexible filler primer, guide coat and block sand. Once you're happy with the prep work apply your top coat but realize that ANY hardened paint like single stage urethane or clear coat need to have a flex additive to help stop if from cracking.

    If you want this to look good for a long time use high quality products. Don't buy cheap paint because it usually won't stay flexible as it ages.


    The next one of these jobs that I do I'm going to try Fusor Cross Bonding Adhesive to bond the glass to the metal but I would probably still use the Dyna-Weld to finish the job because the Fusor is not a filler product it's a glue.

    Thanks Len. I appreciate your direction in this and will keep you updated on the progress. Be well. Thomas Little Wolf

  4. #4
    Join Date
    Nov 2005
    Posts
    27,115

    Default

    Quote Originally Posted by poisonivy24 View Post
    Thanks for the great tips, I had the same problem with my car's hood. I am wondering what happens to your car now after you use these products?
    By using the correct repair techniques along with the correct products you should get a repair that is stable and holds up well over time. A job like this can crack up over time is the correct method and products are NOT used.

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