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Thread: fiberglass and aluminum

  1. #1

    fiberglass and aluminum

    Attempting to modify some fiberglass body panels with aluminum. Can I cover aluminum with fiberglass resin and cloth without it coming apart over time. Will I have to skim with filler first. Anyone who has tried this before your input would be appreciated don't want problems later. this is my first build and Im kinda winging it.
    thanks

  2. #2
    Senior Member MacGyver's Avatar
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    In my experience. Fiberglass does not stick to aluminum very well at all. Primary I will use aluminum within a fiberglass panel in order to give strengthening for bolting other panels to it. Post some photos of what you are trying to accomplish and Iím sure you will get some good feedback.

  3. #3
    Senior Member Don's Avatar
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    Like Sean said, fiberglass doesn't do well against Aluminum. You pretty much need to use the aluminum encapsulated as a strengthener as Sean states or use the aluminum as the base to give the cloth and resin shape while it cures and then peel off/remove the aluminum off afterward. Not a good idea to put glass over the aluminum and hope it stays to the aluminum long term. It will separate at some point, usually sooner than later.

    Post some pics or an explanation of what you want to do and we can help.

    Cheers
    Don
    308 Ferrari replica
    Prova Countach 5000QV

  4. #4
    no pics yet but i am trying to make a non removable canvas top for 355 spider rep. similar to mcgyvers removable 430 fiberglass top but non removable.
    made shape of top using thin gauge aluminum sheets. wanted to apply layers of fiberglass cloth for extra stiffness and strength before covering with canvas. have heard that alum and fiberglass not best combo wondering if i can skim alum panel with body filler and apply fiberglass cloth to the filler, then cover with canvas.
    thanks guys

  5. #5
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    Wouldn't recommend that you just try to glass over the aluminum. I would be better to bond the aluminum to the fiberglass using something like Marine Tex, JB Weld or one of those other two part epoxy products.

  6. #6
    Senior Member Don's Avatar
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    You still have a few options using the aluminum but just don't expect the aluminum and fiberglass to live a long life stuck together. They will separate at some point in the future. You can do one of three things if you are looking for more stability:

    1. Skim coat and sand the top with body filler to get the smooth shape you want. Take a mold of the aluminum top you have built and pull a fiberglass piece from that mold and not use the aluminum at all.

    2. Add reinforcements to the aluminum from the underside using aluminum square, L or T bar etc. and use the body panel glue that has been shown here a few time and not use fiberglass at all. Still skim coat the top part to get the final shape you want and then cover with the fabric.

    3. Put the fiberglass over the aluminum with enough thickness (2-3 layers) to not flex and then cover the inside of the top with another couple layers of fiberglass to sandwich the aluminum. To help counter the aluminum/fiberglass separating, you can drill 1" or so holes in the aluminum top every several inches before covering with glass. This will put a connection between the inner and outer fiberglass surfaces to help keep the inner and outer fiberglass pieces together and not worry about the separating that would arrive with a full aluminum sandwich. You will need to sand and smooth the fiberglass anyway so any dips created by the holes can be sanded and filled anyway.


    No magic answer unfortunately. Just a bunch of work........

    Cheers
    Don
    308 Ferrari replica
    Prova Countach 5000QV

  7. #7
    thanks for your input fellas
    Don your first suggestion is obviously the best but im not skilled enough at this point, so it looks like you second or third suggestion or a combination of the two is how i will go.
    thanks again.

  8. #8
    Senior Member MacGyver's Avatar
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    Looks like Don has gave you some good suggestions.
    As you know, I decided to use the original top sheet metal and modify it for my needs. That’s another option you may want to consider. If I was planning on making a non-removable top I would probably do about the same thing except for adding bracing and welding it to the rest of the car. When using the original top inner structure, you also have the benefit of having all the correct angles for your weatherstrips and etc. (in other words – why reinvent the wheel) I think I paid about $75.00 from the bone yard for the inner Fiero structure. Large fiberglass repair shops also carry sheets of foam that you could add to it to create just about any shape you want before covering it with fiberglass. Much easier than trying to shape aluminum. Aluminum is great in many situations. It’s light weight and strong. Although it has a lot of drawbacks. You can’t weld it to the steel chassis. That’s the biggest one.

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