Fibreglass tank repair

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Apr 2, 2008
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Hi All, my Norvil tank has developed a hole on the inside(frame tube side), I have some JB Autoweld cold weld & it says will repair plastics, does anyone know if that includes f/glass? I have tried their website with no success.

Easy... well sort of

Fiberglass is somewhat easy to repair, just rough up the area next to the "hole" and put a few layers of fiberglass cloth soaked in resin on it, sand a bit and it should be as good as new. Use woven cloth if the hole is big, it spans better. You can buy repair kits at most auto parts store which includes everything you will need. Make sure to read the directions carefully before proceeding, wear gloves and do it in a well ventilated area.

I don't know about using a few thin layers of 'glass repair on a tank that has multiple layers with an aggregate thickness over 1/4". However, I also don't have first-hand experience either positive or negative, so pay no attention to the little man behind the keyboard.
Of course, thicker is better...

You are right, thicker is better, but some of the thickness of the tank is required for structural integrity and it's not done the same way, they used chopper guns which shoot fibers laced with resin, the same way it is done for boat hulls. The chopped fiberglass has less structural strength than woven cloth, that is why it is thicker (they also had to account for some idiot sitting on the tank trying to get the back end lighter to burn up that rear tire and this is something I will never admit having done in my early years of ownership of my 1969 blue Commando S :lol: )

What I would do is open up the hole by grinding a very gradual slope, then put as many layers as it takes to get it flush with the original bottom, then sand the surface smooth without forgetting to fix whatever caused the hole in the first place.

I know one thing, Dunstall tanks are build with multiple layers of sheet 'glass laid in a mold, no chopper gun there. MUCH stronger.

Admittedly, a really solid structural patch would be a nightmare, where a suitable patch can be done just as you suggested.
Many thanks all, nothing was rubbing on the tank, it had blistered from the inside so suspect dodgy fabrication process.
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