Molding in a hood scoop

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1BadDodge71

1BadDodge71

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I have a fiberglass six pack hood scoop on the way for my Duster and although I have been in the auto body industry for some time now,Im still not afraid to ask for opinions so here it goes.Ive molded in a couple of these in my life.One was a cowl induction on a Chevy s10,turned out great but years later saw the truck for sale at a used car lot.SO I went to check it out and saw it was barely starting to crack( I guess it never cracked for the original owner even though I told him I couldnt guarantee it would never crack)The other car was a snorkel hood scoop I did on my brother 74 Duster and that one lasted for 3 years but started to develop a small hairline crack up front.Ive even molded in ground effects for peoples ricers(yuk,but I needed the money,lol)and I even told them there was no guarantee it would never crack.On the hoods,I stripped the hoods down to metal first,made sure the scoop was lined up correctly,revited on,and then I roughed up the surrounding edge of the scoop so the filler would bite.I then spread kittyhair around it,sanded it until it blended in,skimmed it with a light coat of Evercoat filler,then finished it with some glaze putty ,and primered it.
I want to know what some of you use or what methods because I plan on keeping the car for along time and do not want it cracking so soon,or ever.Im thinking slamming the hood too hard contributes to cracking,and the heat of the sun and the cold.
Im open to advice,thanks!:cheers:
 
Maybe a mettalized body filler would be less prone to cracking. It's what I use to fill in the factory gaps once all the lead has been removed. Everything you mentioned sounds great,it's the way I would have done it and I have been in and out of body shops for years.
 
Thanks.I may look into a metalized filler,but will it adhere to the fiberglass?A friend suggested I use 3M panel adhesive but Ive been told its a pain to sand.I originally wanted a fiberglass hood with a scoop already molded but those are way beyond my budget,lol.
 
Panel adhesive is good stuff. Just do your clean up right away after glueing whatever on and you wont have anything to sand.I like this idea. Rivets tend to losen up after a while so could make crackin g worse
 
My old man used to use this stuff called alumiglass and he never had a problem with it cracking over the years like kitty hair does. Like mentioned earlier in the thread its a metalized filler. This stuff was aluminum and fiberglass mix. If I was gonna mold a scoop on I would go that route with some type of metalic and fiberglass mix.
 
thanks for the input guys,I really appreciate it.:thumbrig:I will look for that alumniglass tomorrow,hopefully my paint store carries something like that
 
 
The way i would do this is to glass the scoop with a inside flange and make it a bolt on scoop you can put a piece of plastic sheeting on the hood lay out some glass and place the scoop on it and let it dry it will fit the hood perfectly .remove it and reinforce it on the inside with some layers and you have a inner fange to bolt the scoop to the hood .
 
Why go to all the trouble of making a fibreglass inside flange? Wouldnt aluminum for the inside flange make the whole area stronger?
 
needsaresto said:
Why go to all the trouble of making a fibreglass inside flange? Wouldnt aluminum for the inside flange make the whole area stronger?
Click to expand...
what u r doing is is altering the scoop so it is a bolt on useing the same material . the problem you deal with when you bond a scoop to a metal hood is you have too diffrent materials metal and fiberglass that with the change of tempature heat and cold will expand and contract diffrently and add in the vibrations over time stress the bond and it cracks .
 
I've always heard that there is NO WAY to smoothly bond fiberglas to steel without cracking. May last 3 months or 3 years, but cracks will happen. I think you are right about slamming the hood exasperating the problem, but think about the temperature changes a hood goes through. In cold weather when the engine warms up (or overheats) that's the hottest part on the body, then you shut it down and it cools off very quickly, fiberglass and steel expand and contract at different rates and BAM a crack. If someone comes up with a method that works, I'd love it, until then just plan on re-doing the scoop area every few years.
 
Here is what I did and I am yet to have a crack. I used body panel adhesive and bolts. Fiberglass filler and then a skim coat of mud. So far so good.
 
nice,you guys are doing great on those scoops.:cheers:
Well,my scoop arrived today but damn,i wonder if its too big:dontknow:Ill post some pics and hear your opinions
 
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The body line on the hood makes it difficult too.This scoop is not flimsy or flexible at all,its very solid
IMG_0330.jpg
 
if the scoop fit the hood really nice i wouldnt try to go for the seamless look. its always going to be a steel hood with a scoop added. why hide it. i think rivets look better than cracks in fresh paint. foward facing scoops take in a ton of air when id drive down the highway with my aar 6 pac hood the hood would be flexing all over the place. it always freeked me out. enough to get rid of it.

i think the best way to go is panel adhesive with rivets or machine screws and nuts. remove them after its set then use fiberglass reinforced filler. shape it close with a slow body sander/grinder and a big 80 grit disc, skim coat most of the hood with a lightwieght body filler and block it flat.
 
Any update Bad Dodge71? I have same hood and was thinking about getting a similar scoop.

Take it easy,

Bad Shrimp
 
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