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Fiberglass experts, help with hood

Posted By: 440Satellite

Fiberglass experts, help with hood - 11/07/10 06:49 AM

I just picked up a cheap raceweight 6 pack hood for my Dusterand need some advice. I needed some hood clearence for running a taller intake and air cleaner and got a good deal on the hood, its a pin on using zdus fasteners and is a thin race weight hood from MAS. I'm looking into adding some extra reinforcement to the underside to stiffin it up. I was thinking about using the smallest aluminum square stock bent to the shape of the stock hood and making a square frame and fiberglassing it to the underside then adding an extra layer or 2 of fiberglass to the entire underside of the hood and scoop. Sound like a good idea or is there a better way?

Also the the back corners of the hood where it meets the corner of the cowl and fender are a little rounded off, not pointed like the factory, is there a good way to add some material to the corners to make it fit better? Is this posible and how would I go about adding to the edge of the hood?

Any advice would be greatly appriciated. I really havent done much fiberglass work but I pride myself on learing and doing new things, love the challenge and it always comes out great once I do some reserch and dive in . Any fiberglass experts out there that can share some tips on this project? Thanks

Butch

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Posted By: dOrk !

Re: Fiberglass experts, help with hood - 11/07/10 07:09 AM

Butch ...let us see the underside of the hood ..
Posted By: 440Satellite

Re: Fiberglass experts, help with hood - 11/07/10 01:32 PM

Ok I'll take a picture of the underside today.

Butch
Posted By: crlush

Re: Fiberglass experts, help with hood - 11/07/10 03:51 PM

some of the lightweight hoods underside it looks like they use foam padding cut in strips and then they just fiberglass over them basicly creating a rib to stiffin the panel, on the corners you need to roughen it up with some course sandpaper, and you could mix up some resin and fiberglass mat (I like the gorilla hair type, and add what you need.
Posted By: 440Satellite

Re: Fiberglass experts, help with hood - 11/07/10 05:08 PM

Looks like they used a strip of cardboard fiberglassed in but I want something a little stiffer. Heres a picture of the underside. I was thinking about adding the aluminum strips about 2-3 inches in from the edges and then making the entire hood a little thicker with an extra couple layers of mat. I'm going to take out the plexiglass that partially covers the scoop hole but I might add something simmilar cut to fit my air cleaner, seems like a good idea to really force the air in. So what do you think?

Butch

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Posted By: 440Satellite

Re: Fiberglass experts, help with hood - 11/07/10 05:09 PM

And heres the corners as I mentioned...

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Posted By: Boise Chall

Re: Fiberglass experts, help with hood - 11/07/10 05:18 PM

I'm not a fiberglass expert by any means but this is what I've done. First you need to figure out what kind of fiberglass you have fiberglass or SMC fiberglass is kind of a clear yellowish color SMC is gray in color and get the right resin for it. If you're not sure they make a resin that works on fiberglass and SMC talk to your bodyshop supply place. get a piece of wood from home depot 1x2 or 2x2 whatever you have room for under the hood. Cover the wood and your work area surface with clear plastic packaging tape then spray the tape with Pam cooking spray use some fiberglass mat and resin and cover the wood with it on 3 sides making a -U- shape. Let the mat and resin run out onto your work surface about a half inch to make a -U- shape with wings on the top. Let it set up then remove the fiberglass from the wood and work surface clean the piece with wax and grease remover (from bodyshop supply place) cut your piece to fit under the hood scuff the bottom of the hood and the top of the piece you made with 120 grit sand paper and bond it on using panel adhesive or fiberglass resin. For the corners of the hood that you said are rounded off grind the top of the hood back about a half inch on an angle put a piece of packaging tape on the underside of the hood sticking out over the edge of the corner. (> Don't use the Pam cooking spray on this repair < ) Use long hair fiberglass filler to make your corner. Pull the tape off after it sets up then shape it to fit.
Posted By: Boise Chall

Re: Fiberglass experts, help with hood - 11/07/10 05:20 PM

I just saw the pic you put up I would say that's Fiberglass not SMC
Posted By: 440Satellite

Re: Fiberglass experts, help with hood - 11/07/10 05:54 PM

So doing it that way your actually making u channel fiberglass suports, never thought of that, good idea.

Out there looking at it again, I'm thinking about doing away with the zdus fasteners and running 4 pins in the corners. I was thinking about forming some aluminum angle stock to the contour of the fender tops and mounting them on the inside of the fenders and along the top of the back cowl area making a ledge on 3 sides for the hood to sit on to keep the shape. Then adding a 2 or 3 inch strip of flat aluminum stock along the underside in line with the pin mounting locations. Basically have a long strip on each side of the hood fiberglassed in, down the entire length of the hood on the sides so that the front and rear pins would both go through the same strip of aluminum for added strength.

Starting to think that the zdus fasteners may be a real pain for a street car.

Dont know if I explained it very good, but get the idea? Any thoughts?

Butch
Posted By: dOrk !

Re: Fiberglass experts, help with hood - 11/07/10 06:55 PM

I have not seen bracing like that in a long time ..

How stiff is the hood as-is ?
Posted By: CrazyD

Re: Fiberglass experts, help with hood - 11/07/10 06:58 PM

I glassed in a balsa wood frame
Posted By: 440Satellite

Re: Fiberglass experts, help with hood - 11/07/10 07:20 PM

Quote:

I have not seen bracing like that in a long time ..

How stiff is the hood as-is ?





Its not awfull but it does have some flex to it especially on the edges. Any ideas?

Butch
Posted By: dOrk !

Re: Fiberglass experts, help with hood - 11/07/10 07:37 PM

First .. you never put a hood on the rear tips !! ... that is why yours is sooo rounded-off.

OK ... how much concern is additional weight?
Posted By: 440Satellite

Re: Fiberglass experts, help with hood - 11/07/10 09:18 PM

Gotcha, makes sence!!!!

Weight is not an issue as its not a race car, more interested in duabillity and strength. Dont want it so heavy that its a pain to lift on and off, but no mater what it will still be way lighter then the stock hood.

Butch
Posted By: dOrk !

Re: Fiberglass experts, help with hood - 11/07/10 11:29 PM

LAST Q before my recipe ...

Can you flip the hood over and put it on some saw-horses without it changing contour?
Posted By: 440Satellite

Re: Fiberglass experts, help with hood - 11/08/10 12:46 AM

If I did, it probably would change the contour. So I was thinking about taking some 2x4's and making a square and shaping them to the contour of the top of the stock hood, so one down each side and one in front and back. It would take some work to shave them down to fit the contour but I figured I could them use that frame to set the fiberglass hood upsidedown on and it would be the same as the stock hood, then fiberglass. Sound like a decent idea?

Butch
Posted By: dOrk !

Re: Fiberglass experts, help with hood - 11/08/10 01:08 AM

THERE you go ...with the 2x4's ....

but if that flexes THIS much ...THAT is plain WRONG

OK ... get some CONDUIT(or sim-size alum tube) and BEND-same to fit the underside of the hood on the OUTside of that existing bracing. THEN put a tube in side-to-side just in front of the scoop.

'GLASS-in(1.5 oz mat) ...and you should be good-to-go.
Posted By: Boise Chall

Re: Fiberglass experts, help with hood - 11/08/10 01:11 AM

I've seen them come out of the box brand new with one rounded corner and one square corner and none of the glass looked chipped. almost like they made it that way.
Posted By: dOrk !

Re: Fiberglass experts, help with hood - 11/08/10 01:31 AM

Quote:

I've seen them come out of the box brand new with one rounded corner and one square corner and none of the glass looked chipped. almost like they made it that way.




VERY TRUE ... but what happened is the FG company probably stored the mold ON THE TIPS and wrecked the mold themselves. Some are also FAMOUS for grinding the "flash" off of the finished-part IN THE MOLD ...and then THIS reduces the size of the mold ...and every other part that comes out of that mold.

THIS is why all the molds I made had wood or metal bracing that would extend past the mold so it would keep the mold off the floor.

You would be surprised on how many FG companies do NOT do this ...

It makes working on the mold, prepping the mold, the gel-coat-process, roll-out of the main laminate, the bracing process ....sooooo much EZier.

But they can butter-their-bread as they see fit...
Posted By: 440Satellite

Re: Fiberglass experts, help with hood - 11/08/10 02:46 AM

Doc, Thanks for the advice, much apriciated.

One more question for you, if I remove the zdus fasteners and put a fresh layer of fiberglass on the underside, can I just fill the holes where the fasteners were on the top of the hood with fiberglass filler? And with the tubing for bracing, should I weld the center support to the side tubes or just glass them in, would it add anything to weld it, making one peice?

Also I read about using foam pipe insulation cut in half and glassing it to the underside. Would the metal be a better option or would that work also?

Thanks for everything, time for some fun!!!!

Butch
Posted By: dOrk !

Re: Fiberglass experts, help with hood - 11/08/10 12:35 PM

I am NOT a fan of the zdus at all. They are famous for popping up(if not mounted perfectly) ...and then you can lose the part.

YES on the filling. ALSO ...with the metal tubing ....that offers a TON more stiffness. The foam offers NOTHING but a form for the fiberglass mat bracing. THIS is OK .. but if you are going through all this ...do-it with metal. WELDING IT would be better but not really required.

I have done the metal bracing MANY times in regular production. The trickest ? ....magnesium tube.
Posted By: 2boltmain

Re: Fiberglass experts, help with hood - 11/08/10 01:07 PM

I bought a flat hood from AAR and had to cut a hole in it for the dual quads. I called AAR since I would have been cutting thru the bracing/structure. They instructed me to buy a celotex styrofoam insulation sheet. Following their instructions I cut some strips and placed them on the underside of the hood. I completly glassed them over and all was good. The hood was structurally sound and my carbs and air cleaners were poking thru. (Added a scoop later)
Posted By: dOrk !

Re: Fiberglass experts, help with hood - 11/08/10 01:24 PM

AGAIN I say ...

ALSO ...with the metal tubing ....that offers a TON more stiffness. The foam offers NOTHING but a form for the fiberglass mat bracing.

...and the same goes for that styrofoam sheet.
Posted By: jcc

Re: Fiberglass experts, help with hood - 11/08/10 10:45 PM

Quote:

AGAIN I say ...

The foam offers NOTHING but a form for the fiberglass mat bracing.

...and the same goes for that styrofoam sheet.




, but then thats all it's supposed to offer, the increase/added stiffness is not the foam itself, its the increase in the depth of the cross section ( it could almost even be just air , except that is hard to form)that one is trying achieve. Steel ubing mightwork well and easy, but hard to imagine it outperforms foam lb for lb.
Posted By: 2boltmain

Re: Fiberglass experts, help with hood - 11/08/10 11:50 PM

I was told the foam is just the form/mold and that the cured fiberglass is the where the strength lies.
Posted By: Stanton

Re: Fiberglass experts, help with hood - 11/09/10 03:38 AM

Most definately.

Y'know, with what you're starting with and the end result you want and the time and effort its going to take to get you there, you'd be WAY better off just buying a new hood. Even the less expensive lower end units will be far better than what you're likely to end up with. F'glass is not the most enjoyable stuff to play with.
Posted By: 440Satellite

Re: Fiberglass experts, help with hood - 11/09/10 12:33 PM

I dont agree, its really not a bad hood as it sits, I'd have no problem using it as is, once all the zdus btackets are in place it would sit nice and straight. I just want to beef it up a bit to make it stronger and as far as the corners go, if there easy enough to fix, I'll fix em, if not its no big deal.

For some of us, working on our projects is the best part of having one. I enjoy working on them even more then driving them, I'm usually looking for something to work on or modify.So somthing like this I look foward to.

Butch
Posted By: dOrk !

Re: Fiberglass experts, help with hood - 11/10/10 03:17 AM

Quote:

I was told the foam is just the form/mold and that the cured fiberglass is the where the strength lies.




Very true ....foam offers ZIP in strength ....BUT IF you put some mag, alum or lite-weight steel tubing in there ... the hood is almost as stiff as a steel hood.

I have done this on at least a 100 hoods.
Posted By: dulcich

Re: Fiberglass experts, help with hood - 11/10/10 05:29 AM

Quote:

Quote:

I was told the foam is just the form/mold and that the cured fiberglass is the where the strength lies.




Very true ....foam offers ZIP in strength ....BUT IF you put some mag, alum or lite-weight steel tubing in there ... the hood is almost as stiff as a steel hood.

I have done this on at least a 100 hoods.




Don't question the Doc. Well at least not on Fiberglass. He is offering a very sensible and practical fix. Sure you can stiffen it with a top-hat of glass on a core of anything, but the conduit is easy to work with and will add additional stiffness.
-dulcich
Posted By: dOrk !

Re: Fiberglass experts, help with hood - 11/10/10 06:01 PM

Quote:



Don't question the Doc. Well at least not on Fiberglass. He is offering a very sensible and practical fix.

-dulcich




Why THX d-guy ..... but shouldn't you add in-there NOT questioning me OR you about the superiority of the Plastic-Fantastic ....aka ThermoQuad ?

SHOULD we sign-you-up as part of the ThermoSquad?
Posted By: 440Satellite

Re: Fiberglass experts, help with hood - 11/11/10 01:39 AM

Hey Doc, any tips on adding material to the edge, as is the case in my corners. Should I just use a flat surface butted up to the topside of the hood and overlay a few layers of mat from the underside to build it up?

Gonna build my wood stand tomorrow fitted to the stock hood so I can lay the fiberglass hood down and start working on it.

Butch
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