What's the best way to bond a fiberglass hoodscoop to a metal hood? My plan is to pop rivet or screw the scoop into place, then glass over the fasteners and all around the scoop. Good/Bad idea? Just looking for some input,
I've done the screw/rivet thing, than 'glass over it. done it on a couple hoods--each one of them cracked within a couple days. There is a "glue" that watercraft and boat companies use to bond hull pieces together, and it's also used to bond the metal engine mount plates to the 'glass hull. A buddy used this stuff (cant remember what it's called) on his 64 falcon sprint, worked perfectly.
I used 3M structural adhesive. I could not find the adhesive Harwood suggested but I found the 3M stuff.So I called Harwood and asked them if they knew anything about that stuff and they said it was a good product.I put screws in to hold it while it set up and them removed them. But the hood is just going back on this weekend so I cant tell you how it will do in the long run. It made a good job of it anyway.filled the holes on the bottom and painted. Looks like a factory hood.
I took a Cobra Jet fiberglass scoop and bonded it to my steel hood about 6 or 7 years ago and it has held up perfectly with no cracks at all. I basically cut the hole in the hood and then laid down a coat of Gorilla Hair fiberglass all around the opening where the scoop was going to sit. Once the scoop was in place and was where I liked it, I let the fiberglass set up and then ran more fiberglass on the top of the scoop where it mated to the hood. It took a lot of sanding and shaping because once the Gorilla Hair sets up, it's hard as a rock. But once it is on, it is waterproof and strong as s***! It has held up great and there are no cracks in it at all (note: fiberglass flexible). I think laying down the fiberglass first and setting the scoop in that probably has something to do with it since it is bonded to the hood from the underside and the top side. I have seen other scoops and they have cracks in them because people just bolt or rivet them and then use Bondo to blend them into the hood. They all crack when done this way. Do it with real fiberglass with actual strands of fiber in it and you will have a scoop that is on there permanetly that won't crack.
Epoxy will hold fiberglass to steel. Polyester filler can be used to smooth the joints but it isn't a good glue. Any long cure epoxy will work so as long as the cure time is about an hour you can pick the least expensive epoxy you can find. DO NOT USE 5 minute epoxy! you will need more time to work with it and it doesn't hold as well as the slow cure epoxy.
have you thought of windsceen bond. i work for a company here in the uk that fits windscreens and that glue is bloody strong! its polyurethane based black sticky muck lol but it will hold anything and i mean anything together, im not to sure if you can paint it though?? probably can with ther right stuff. the company that makes the stuff i use is DOW and you have to use primer paints to make it stick to bodywork and glass - maybe you might be able to get hold of similar stuff over your land.