fiberglass hood.
Printed From: the12volt.com
Forum Name: Fiberglass, Fabrication, and Interiors
Forum Discription: Fiberglass Kick Panels, Subwoofer Enclosures, Plexiglas, Fabrics, Materials, Finishes, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=43850
Printed Date: April 29, 2024 at 2:14 AM
Topic: fiberglass hood.
Posted By: placid warrior
Subject: fiberglass hood.
Date Posted: November 26, 2004 at 6:50 PM
this isnt an audio topic, but i was wondering how good a fiberglass hood would work out. I was thinking o f replacing my steel hood with a fiberglass hood....but i cant buy them, so i want to make one...i like the steel one i have so i'll just make a mold from it. It would have to be done in 2 pieces, top and bottom, and then fused together. Would the sections of the hood that attach to the hinges on the car be strong enough with just fiberglass? or would i need to rienforce it with a piece of steel....its a pretty big hood with a scoop on it. to fuse the pieces i was thinking of fiberglass resin with a lot of filler material...would that work out allright? how many layers would be good for each piece? 5 or so? once its fused together it would total 10 layers plus the filler to fuse them.. anyone have any advice or ideas? thanks.
Replies:
Posted By: boxmaker85
Date Posted: November 26, 2004 at 9:18 PM
All I am saying is get a profesional. I'm not doubting your ability w/ fg but something like that takes some serious knowledge of material, tools, and expertiese in that field.
Posted By: placid warrior
Date Posted: November 27, 2004 at 12:15 AM
whys that? it seems pretty basic...make it strong enough to not break, make good attachment points and use hood fasteners to secure the hood from flying off....I wouldnt go as far as making fiberglass panes, but a hood doesnt seem so bad....anyone else have opinion on wehter or not i should try this....actually to tell u the truth i most likely will end up trying it no matter how bad it comes out...heck its worth the try...so any other opinions?
Posted By: auex
Date Posted: November 27, 2004 at 12:23 AM
placid warrior wrote:
whys that?
It is for safety reasons. If you make a hood then rear end someone then the hood won't crumple like it should, and possibly decapitate someone in your car. ------------- Certified Security Specialist
Always check info with a digital multimeter.
I promise to be good.
Tell Darwin I sent you.
I've been sick lately, sorry I won't be on much.
Posted By: placid warrior
Date Posted: November 27, 2004 at 12:44 AM
hmm..thats a good point. what if i made spots that were break points for if i were to get in an accident? make it thinner so it will for sure crumple in those spots?
Posted By: auex
Date Posted: November 27, 2004 at 2:01 AM
I don't think anyone on this board is qualified to answer the crumple zone issue, unless there are some mechanical engineers that can yay or nay something here.
This is assuming you know how to use most of the composite materials that would be involved in the taking on of such an adventure.
All right, I am not advocating this but what I would do is (with the hood still bolted to the car, that way the mold is exactly as it should be on the car and the hood doesn't flex) to go ahead :
1. lay masking tape over the hood
2. then apply some foil as smooth as possible over the tape.
3. Then mask off the fenders, bumpers, glass, and anything else you want to protect.
4. Then with fiberglass cloth, I think cloth would be the easiest for this type of piece at this phase, cut and lay the pieces out over the hood to get the first layer.
5. Then mix your resin, but don't mix too hot or you could damage the paint on the original hood.
6. Then just working across one way or the other, just don't start somewhere and jump to the other side, lay one piece of the cloth and glass it down working out any bubbles as you go.
7. When it comes to the next section, make sure to overlap a little ( about 1/4 inch min) and do the same thing until you get across the hood.
8. Once the resin has had AMPLE time to cure then remove the piece and start adding layers of fiberglass matt to the underside of the hood until you reach the thickness that you want.
9. Let it sit for a day.
10. Then take a look at the underside of some of the carbon fiber hoods, factory hood for that matter, for their support structure, the mini beams running under the hood that actually give the hood support. And draw up a game plan for doing these.
11. What I would do is get some expanding foam, I know resin will eat right through this but just need it for shape, and run all of the supports through with this first. Run your lines and let them dry for a couple of hours.
12. Then take some strips of matt and then cover all of the foam with the matt and then glass that to the underside of the hood.
This is what I have come up with to do something similiar, you know something to do when there is nothing else to do and I am bored.
Also you should expect to be mounting this hood with pins so come up with something for that.
Also, Also I am typing this at 1 AM on Ambien, so it should be pretty straight forward and I will look at it again when I can think straight.
-------------
Certified Security Specialist
Always check info with a digital multimeter.
I promise to be good.
Tell Darwin I sent you.
I've been sick lately, sorry I won't be on much.
Posted By: civicdetailer
Date Posted: November 27, 2004 at 8:18 AM
what kind of car is this that you cant buy an aftermarket hood?
Posted By: boxmaker85
Date Posted: November 27, 2004 at 9:18 AM
As a mech engineer I will say this (as previously stated) designing a hood for a car takes extreme knowledge of mechanics of materials (what the hood is made of and how the material works with different forces), you need countless different types of equipment to test and determine weak points on the hood, then you need somthing (another machine sensor type of equipment) to test how strong the hold is on the hood. If you are doing 70 mph on the highway (or more) the force of the wind acting on that hood is very very extreme. It's like designing a wing for an F-16 (maybe not that extreme but you get what I'm going for). And then as far as attaching it, like auex said you need pins. That's another area of mech engineering in itself. You need pins that will be able to support a very large sheer force. And also resist torsion (twisting of the pin). And then you get to decide do you want single sheer pins or double sheer pins? What type of material do the pins need to be made out of? What size? ect... And since the hood is having a different shape and different weight and properties you need different supports on it. My advice if you do try is go with carbon fiber. This is probably the strongest material available comapred to it's weight. Also Kevlar is good. But if you choose fg then cloth (not mat) is the best/ideal choice. If you think you can do it or are at least up to trying then yeah power to you. But don't come back in a couple of weeks going "Why did the hood rip off the front of my car and shatter into a thousand pieces"? But if you're game then I'm interested to see how it comes out.
Posted By: vinspo
Date Posted: November 27, 2004 at 9:22 AM
You must make a reverse mold first due to the size of project. Your mold must be very solid with no flex to it, about 3/4" to 1" thick with edge bracing. If the mold is not done properly, your hood will be wavy. Manufacturers use a chop gun for buildup, by hand this will be a tedious job with poor results. What I mean by poor is, due to the area of the hood, keeping air bubbles out will be difficult if laying up by hand. My last concern is Safety. Do you really want the responsibility of your hood flying through the air at 65mph on a busy freeway?
Posted By: boxmaker85
Date Posted: November 27, 2004 at 9:22 AM
P.S.- Oh and don't forget the dynamics of the hood. Is it aerodynamic enough? And will the hood crumple correctly or will it give it a weak spot in the hood and break when you're driving? Just do me a favor and tell me where you live so I never have to drive in that area and possibly get in a wreck with you and (like auex said) have myself or someone in your car sliced clean in half. 
Posted By: auex
Date Posted: November 27, 2004 at 11:21 AM
I stand corrected, there is at least one person qualified to say whether or not you should do it.
-------------
Certified Security Specialist
Always check info with a digital multimeter.
I promise to be good.
Tell Darwin I sent you.
I've been sick lately, sorry I won't be on much.
Posted By: boxmaker85
Date Posted: November 27, 2004 at 7:45 PM
Not really qualified but a little knowledge, yeah.
Posted By: placid warrior
Date Posted: November 28, 2004 at 12:15 PM
allright then. Thanks guys for shedding some knowledge on the situation. It would be a really awesome thing to have a lighter car as mine weighs over 3500 lbs. Its a mercury monarch which is why i cant buy any aftermarket body parts for it. the hood i have is pretty wavy because i didnt take the time to bondo it...the only parts of the car that are perfect are the front fenders, but thats cause i spent many hours on them by hand...rest was done with power sanders and little body work...heck, its not a show car. and the edge of the hood thats not flush is due to a bad hood alignment...that will get fixed soon. 
Posted By: 7zark7
Date Posted: November 29, 2004 at 2:23 PM
Are you people kidding me? I mean come on. Do you really think that all of these clowns out there making fiberglass and carbon fiber hoods are doing all of these "calculations" to figure out crumple zones and such? Hell no! Besides, does that car even have crumple zones? Looks like a full frame car to me. Build the hood. As long as the rear mounts are strong enough, they will hold while the hood folds in half during an accident. And as loong as the hood is strong enough, it won't rip through the hood pins and fly up at 80mph. Then again, what do I know. ;)
Posted By: dxav
Date Posted: November 29, 2004 at 3:02 PM
I would leave the hood alone. Though, you could cut away a large portion of your existing hood, and modify a fiberglass hood scoop. Your car really doesn't have any curves, so the 'glass would be simple to mold.
You may be able to shave 50 lbs or so, but would you really save anything?
Anything else would be crazy to try, and most likely dangerous.
Just my thoughts,
DXAV
Posted By: realitycheck
Date Posted: November 29, 2004 at 3:53 PM
If you want lighter, I think I would make fiberglass bumpers and get rid of those steel ones. Does your car have sound deadening material in it because if it does you could rip all that junk out and tub the thing. Also I like the idea of just cutting that hood scoop off and making a new scoop.
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Learning the trade one fiberglass creation at a time!
Posted By: boxmaker85
Date Posted: November 29, 2004 at 7:10 PM
Uh yeah actually 7zark7 these guys that build hoods (if it's a mass production hood) actually have to build them with some safety in mind (dot will be on their @$$ otherwise). And that means crumple zones and lots of calculations. And also that car probably does have crumple zones. Might not be very big (or very effective) but there are "soft" areas in that frame that will give in a wreck. But as far as what to do w/ this car.... have to say it, Get a new car. You're not going to be able to make this one much lighter. But if you're happy w/ it enough to keep it then don't expect to get too much lighter. Also look into maybe doing a fg trunk lid. That's very possible and probably not too hard to do. Just my $.02
Posted By: placid warrior
Date Posted: November 29, 2004 at 8:42 PM
thanks for all your comments guys. i may do a fiberglass scoop, it should stick fine right? I just have to talk to the guy that made my paint and see if he can make the same mix again cause i also want some for my fiberglass projects. I actually just picked up a 302 on saturday night, its in running condition, but I'm gonna rebuild it....rather than go lighter i think i'll go with a bigger engine....this car is more my project car...i love it cause i put so much into it...i will sell it though when i manage to make a few extra bucks for a nicer car, but i still like the older cars, so i'll just make sure it has muscle...hehe...i also found a turbo that i might buy...gonna look at it tomorrow....I'll put that on my inline till i get the 302 built up. I dont have a whole lot of sound deadening...i plan on replacing my carpet and laying down a layer of Ice and water shield stuff then. anyone have ideas for the hood scoop? or should i make it similar to the one i have now? or should i just mold the scoop and then remove the metal one and fuse on the fiberglass one...it'll look better and smoother than what i have now and i kinda like the scoop i have.
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