44070dart
How the hell did I get this old..
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Looking for what kind of bonding material to use to bond a scoop to my trucks hood.
Bond a fiberglass scoop to a steel hood
- Thread starter 44070dart
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MidnightSwinger
Well-Known Member
Subscribed, I’m about to do the same thing.
Bet 3M has something, I would call them.
Trace around your fiberglass scoop on the hood to mark it's location.
Then grind back the paint on that area with 36 grit, same rough up the mounting surface of the scoop with 36 grit.
Then cut long pieces of fiberglass matting 1" wide soak them in catylized fiberglass resin and apply them to the hood in the area that you traced out for the scoop. 2 layers of the fiberglass matting.
Now brush fiberglass resin to the mounting face of the hood scoop and set that onto the Fiberglass matting and let it dry overnight.
Follow up with body shop procedures for filling and shaping to contour, prime and paint.
Can put some weights on the scoops to hold them down while they are curing the bond.
Not drilling holes in the hood for mounting is a good thing. If things would ever change you can strip them off with paint stripper without destroying your hood in the process.
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Then grind back the paint on that area with 36 grit, same rough up the mounting surface of the scoop with 36 grit.
Then cut long pieces of fiberglass matting 1" wide soak them in catylized fiberglass resin and apply them to the hood in the area that you traced out for the scoop. 2 layers of the fiberglass matting.
Now brush fiberglass resin to the mounting face of the hood scoop and set that onto the Fiberglass matting and let it dry overnight.
Follow up with body shop procedures for filling and shaping to contour, prime and paint.
Can put some weights on the scoops to hold them down while they are curing the bond.
Not drilling holes in the hood for mounting is a good thing. If things would ever change you can strip them off with paint stripper without destroying your hood in the process.
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The best bonding products will eventually crack because of the different expansion rates of metal and plastic. I'd use some cool looking bolts.
It's called panel bond, 2 part adhesive and it is expensive.
If it works is all that matters. I have had scoops bust at rivets and bolts as they get old and become brittle.
I like Norton speed grip line of adhesives, seam sealers, etc. Expensive stuff but its very good. However, I agree that you should use hardware with a layer of seam sealer.
ACME SS
Well-Known Member
There is a problem here. There are two types of resin and they are not compatible. Epoxy and Polyester. Epoxy will not adhere properly to polyester and vice versa. If you sand a part of the scoop and it has a floral smell it is polyester and you must use polyester resin. If it has no smell it is epoxy and you must use epoxy resin. It may "work" but it will almost surely crack or fail otherwise.
Epoxy will bond just fine over cured and prepped polyester but not vice versa.
Kendog 170
Let the boy go !
Mine's bolted with caps.
dodgedifferent2
Well-Known Member
I riveted scoop to hood then fiberglassed for smooth transitions and to hide the rivets.
Has not cracked in the 6 years since I did it, but has not seen many miles the last few years.
Has not cracked in the 6 years since I did it, but has not seen many miles the last few years.
Is polyethylene and polypropylene a polyester?
I talked to the AAR representative several yrs ago at the Mopar Nats about glass hoods and scoops. He said the SS/AH guys did not bond their scoops because the joint will eventually crack.
Steel hood and glass scoop? NO Way! You can have the most beautiful paint and it will crack. Studs and nuts like the factory did on the twin scoop semi-snorkel style in the early 70s.
Steel hood and glass scoop? NO Way! You can have the most beautiful paint and it will crack. Studs and nuts like the factory did on the twin scoop semi-snorkel style in the early 70s.
Get some fiberglass resin on a steel putty knife, and then try to get it off....
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Dartswinger70
Well-Known Member
what about that body panel adhesive eastwood sells it. I think i ts a 2 part adhesive.
44070dart
How the hell did I get this old..
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Guys I know say Crestabond but nobody has used it so not a actual piece to see. Thinking rivets and some bonding agent.
Phreakish
Well-Known Member
I've had a few projects which included load-bearing add-ons for aircraft. The installers always used Hysol as a 'liquid shim' and panel bonder. In the past, I never had any kind of resin permanently stick to metal, and things eventually cracked - until I used Hysol. It's serious stuff and has some pliability to it which resists cracking. It takes paint and primers well, and doesn't feel 'gummy', but isn't so hard as to be super brittle either.
We used it on various other sub-assemblies for a while, but went back to rivets because at least they could be drilled out. We could never separate any sheet metal or other components which had been bonded without destroying the parts involved. It's also highly chemical resistant.
We would typically sand both the bonding surfaces with 25-40 grit, bond with hysol, then use a skim layer to fillet/blend the panel line if desired. I think the stuff typically works up to .250" thick too.
I believe that we used Hysol 9394, but it could have been another. I know we tried two, and one was much preferred for it's longer pot life and superior bond strength.
I've never used it for a scoop, but in all the applications I did use it for we never had an issue with it flaking or cracking. When I do eventually install my scoop, I plan to use hysol for that reason.
We used it on various other sub-assemblies for a while, but went back to rivets because at least they could be drilled out. We could never separate any sheet metal or other components which had been bonded without destroying the parts involved. It's also highly chemical resistant.
We would typically sand both the bonding surfaces with 25-40 grit, bond with hysol, then use a skim layer to fillet/blend the panel line if desired. I think the stuff typically works up to .250" thick too.
I believe that we used Hysol 9394, but it could have been another. I know we tried two, and one was much preferred for it's longer pot life and superior bond strength.
I've never used it for a scoop, but in all the applications I did use it for we never had an issue with it flaking or cracking. When I do eventually install my scoop, I plan to use hysol for that reason.
Rivets will always show through.
Think about someone who riveted on a quarter panel in the sail area or below, they always show through. (Because they were not confident enough to use a wire feed).
Rivets and skinning over them will fail, especially if you are cutting out inner structure in the process.
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Dragonsteel
Well-Known Member
Well I guess I broke all the rules after reading this thread! My hood is cut out and my scoop was riveted on when I set it in fiberglass putty, but I did grind off the rivet heads after it had set up. I laid fiberglass cloth over the top, then body filler to level everything out. I did this in September 2015 and it still looks good today. Worth noting that I did brace up the edges of the hood after cutting out the opening. I also used the metal I cut out of the hood to brace up the hood scoop and incorporated a support brace in the center of the scoop to cut down on the flexing from the wind.
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Fusor
has the best bonding adhesive out there. expensive but it works
has the best bonding adhesive out there. expensive but it works
harrisonm
Well-Known Member
Maybe I am missing something, but I don't see where @George Jets mentioned epoxy.
ACME SS
Well-Known Member
You are correct, I was simply trying to help out since when I wrote that I believed what I had said and wanted to make sure there wasn't an adhesion issue. It's not like I hijacked the thread so I don't understand this comment at all. However...
Since then (as of a couple days ago) I have learned that I was given bad information years ago from a couple friends whom I was involved in making composite RC aircraft. I'm currently working on a Smyth Performance car to truck kit and it involves using panel bond to adhere fiberglass components to the steel body of the donor car. After extensive research and talking to Mark Smith (owner of Smyth Performance and founder of Factory Five Racing) I realize that my buddies had steered me wrong. The only thing I can think is that they hadn't properly removed the wax that floats to the surface of Polyester resin during curing and that caused adhesion issues for them. Based on all this, I would suggest using 3M panel bond 08115.
TrailBeast
AKA Mopars4us on Youtube
This is a fiberglass scoop on a steel hood.
It has 6 mounting studs.
I drilled the hood for the studs and set it on, the used a magic marker and outlined the scoop.
Then I took it off and while staying inside the marker line, removed the paint 1 inch inside the line and sanded it hard with 60 grit, and the same with the scoop where it contacted the hood.
I drilled 1/8 holes every inch or so where the two would mate up.
Where that contact area was going to be I buttered the scoop and the hood before placing the scoop on and tightening up the the 6 nuts. (Before the Bondo short strand set up)
Once it was on and tightened down I started working on the contouring from the scoop to the hood.
It’s been 6-7 years now with no cracks or delaminating.
It has 6 mounting studs.
I drilled the hood for the studs and set it on, the used a magic marker and outlined the scoop.
Then I took it off and while staying inside the marker line, removed the paint 1 inch inside the line and sanded it hard with 60 grit, and the same with the scoop where it contacted the hood.
I drilled 1/8 holes every inch or so where the two would mate up.
Where that contact area was going to be I buttered the scoop and the hood before placing the scoop on and tightening up the the 6 nuts. (Before the Bondo short strand set up)
Once it was on and tightened down I started working on the contouring from the scoop to the hood.
It’s been 6-7 years now with no cracks or delaminating.
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