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Thread: Fiberglass hood cracked, how to fix?

  1. #1
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    Default Fiberglass hood cracked, how to fix?

    My friend bought a Ram air hood for his Pontiac Grand Am. The hood was dropped & the entire corner has cracks which go all of the way through to the inside. I don't know much about fiberglass & the search forums didn't help. How do I go about fixing this hood?

  2. #2
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  3. #3
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    i have repaired many of the cowl hoods with shipping damage. You have to v the cracks out before repairing, i would start on the back and use a die grinder to cut the cracks to 1/8-1/16inch deep and also grind around these areas so you can "tie in" your cracked area to the surrounding solid area. you can use some chopped strand mat and resin or some of the newer material such as the SMC panel adhesive. finish with a skim of filler. You would be surprised at the new boat hulls i've repaired because of stress cracks from the demolding process. repaired the same way. Both sides of the fractured area has to be repaired.

  4. #4
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    Quote Originally Posted by sprayboy
    i have repaired many of the cowl hoods with shipping damage. You have to v the cracks out before repairing, i would start on the back and use a die grinder to cut the cracks to 1/8-1/16inch deep and also grind around these areas so you can "tie in" your cracked area to the surrounding solid area. you can use some chopped strand mat and resin or some of the newer material such as the SMC panel adhesive. finish with a skim of filler. You would be surprised at the new boat hulls i've repaired because of stress cracks from the demolding process. repaired the same way. Both sides of the fractured area has to be repaired.
    Thanks for the info. Can you tell me where I can get the products you mentioned? I won't need to put down a wire mesh to strengthen the repair?

  5. #5
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    Anyone else help me out? I'm suppose to do the repair next week.

  6. #6
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    SprayBoy is right. I did a lot of fiberglass work when I had an aftermarket body on my Jeep. As for where to get it, you can get polyester resin and hardener at paint supply houses or even Walmart, Advance Auto, etc. Careful with the catalyst.......it can set up fast if it is really warm and you use too much. Make sure to use mat and not fiberglass cloth. Though you could put a little cloth as the last layer on the outside, but honestly a little body filler over the cured and sanded mat will work fine. I used a paint brush to saturate the mat and lay it into the existing fiberglass (after grinding it out) Make sure to force out air bubble with the brush (cut the bristles shorter if needed for a stiffer brush) If you had larger areas they make a roller for this but that is usually for laying up larger areas not for repairing cracks.
    Now, it has been a few years since I have messed with 'glass, but that is how I did it. I am NOT a pro, so take it for what it's worth. LOL!
    When I saw your post I was afraid that your new hood on the Dodge had cracked!
    Jerry

  7. #7
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    Nov 2005
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    When I can get to the back side of the repair I would normally grind it with a 3" 36 grit disk about 2" from both sides of the crack. I'd grind to lower the surface so that I could wet the surface with resin, stick on a strip of fiberglass mat that will be even or slightly below the surface then I'd soak it with resin and allow it to harden. After it hardens I'd lightly grind off the glaze from the mat and bury the repair with body filler and level, prime and paint it. Now the crack is reinforced and the panel is strong.

    Since my surface is now stable I'd "V" out the crack on the exterior side, fill it with chopped glass and resin, level it then apply a coat of polyester putty to tweak the surface then prime, block sand and paint.

  8. #8
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    Thanks guys. I appreciate the help. I was concerned about the sererity of this cracking...it is kinda spderwebbed cracking that goes to the inside. Just wanted to make sure before doing the work. Thanks

  9. #9
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    Columbus, Ohio
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    cummins,
    Len's procedure is correct, but everyone might have missed a very important point. IF, the hood you are talking about is a factory GM ram air hood, then it is made with SMC. It looks like fiberglass to the untrained eye. SMC takes a different resin to repair. Fiberglass makes one called SMC Resin (http://www.evercoat.com/productDetail.aspx?pID=16)

    Hope this helps
    Dan

  10. #10
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    If it has a shattered look..its probably the gel coat.I take a small bur tip on a die grinder and v it out to the bottom of the crack then use short strand fiberglass paste for those but with the deeper structure breakage,do like Len.

  11. #11
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    Quote Originally Posted by dt196
    cummins,
    Len's procedure is correct, but everyone might have missed a very important point. IF, the hood you are talking about is a factory GM ram air hood, then it is made with SMC. It looks like fiberglass to the untrained eye. SMC takes a different resin to repair. Fiberglass makes one called SMC Resin (http://www.evercoat.com/productDetail.aspx?pID=16)

    Hope this helps
    Dan
    Glad you told me this...it is factory ramair hood. Thanks.

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