Macfreak007

with all of this talk about what kinf of hoods peopel will want to run etc. I have been toying with the idea of making a fiberglass hood. Has anyone else ever done this? This would be for my track car, to keep the weight down quite a bit so the looks are not critical.
I found a few sites with explainations of the process, and it doesn't seem too difficult but i wanted to know your opinions.

Macfreak007

anyone ever thought of trying this?

Dave951M

Yup, but why since there are already some out there like GT racing. If you really want to, go ahead. I was thinking about it but adding the cost of making a mold and the materials, and it doesn't make financial sense to try.

Macfreak007

really? how much do you think that the materials would end up costing? have you already done the math on this?

Dave951M

It's more than the materials, you have to make a mold. Those materials cost. The mold can be from several different materials, plaster of paris is frequently used, but while cheap, has to have a structure to support it. Then you have to purchase the fiberglass and resins. I guarantee you won't get it right on the first shot, so figure at least double on mold costs and time. Then add in another 2x on materials costs. It just doesn't work out for a one off piece. If you were planning on making a number of them and better quality, then you might be onto something. The key factors are value of your time, cost of mold materials, and cost of production materials, and that assumes you're using your hood as the master part. I don't want to throw cold water on your project, just make sure you know what you're getting into. I'm still looking into making a hood with options based on on the louvers and NACA ducts and using CF. It depends on where a break point is on price before I even start thinking of spending money.

Macfreak007

hmmm, good advice Dave, I will look into al of the materials and prices, I might just give it a try if it will not be too terribly expensive, I have a spare hood to make the mold with, If I do end up making one sucessfully I would probably start making more and trying to sell them as a cheap alternative to the other companies out there. Give me a few days to gather information on prices... Let me know if you do decide to carry out your hood project.

Scott at Team Harco

I have made several fiberglass panels for my race cars. I use the internal surface of the skin for the mold. This is very simple and inexpensive. The problem is that it only works with certain types of components. It also requires a lot of clean-up to the internal surface (not that you wouldn't have to do that anyway).

The 944 hood, for example, does not lend itself to this method. As Dave points out - you would make a mold from the master (your hood). This may or may not damage your hood to the point that it would no longer look good. So now you either have a good mold and your original hood is still OK - or you have several less desirable possibilities. Now if you do have a good mold to work with, you still need all the material, supplies, etc to create the fiberglass hood. And - more than likely, your first attempt will not be all that successful.

This is not to discourage your ideas or efforts. It is best that you study the idea carefully and learn as much as you can up front. I was fortunate to have a friend of my father to ask advice of. He ran his own paint and fiberglass business. He made many fiberglass parts some of my father's race cars - so I had no trouble getting to know him. His advice and assistance were invaluable to me when I started working with fiberglass. There are also many books that will help with the basics. My own suggestion would be to start small and become familiar with these basics. I started out making fiberglass bumpers and airdams before I tried any fenders or hoods.

I am working on an article for "Speed, Style & Sound" that describes the method I have used to create my race parts. When it is ready, I will try to remember to post a note here about it.

Macfreak007

Scott, that sounds great, the note would be appreciated, I am going to go book shopping, and I will most likely start practicing on an old 944 front bumper that I no longer need, just to see If I can make it work or not. I think this sounds like a really fun project though, something else I'd love to learn about.

Dave951M

You have PM

Geo

This is the second time I've heard someone suggest plaster for a mold. Question: how do you get a class A finish on plaster? I would also think the danger of pulling up part of the mold would be significant.

I'm making plugs and molds at the moment for parts for my race car. First time for this BTW. My molds will be make from fiberglass.

There was an old edition of Dream Car Garage on Speed where they showed how to make a fiberglass or CF hood for a Mustang using an original hood. Their method for making the parts was to suck the resin into the mold, but up to that point, the techniques should be the same using either wet or dry layup.

kennycoulter

in art school when we did smaller scale things with epoxies and stuff......we did a latex rubber mold for what was to be the closest to the master part. then we had hydrocal(plaster) just as the support. there was chopped fiberglass in with the latex to make it more sturdy........im thinking maybe if you can get ahold of these susbstances, maybe you can make a large shallow tub for the support, and pour in some latex and then lay the hood on there.......that way, instaed of sacrificing a mold(since its not flexible) you can have the giant tub be ramped on the sides so it wont bridge over top of the latex. then pull the hood up with latex on and peel off the latex. but this is just a hypothetical idea that i had. i want to make one of my own designs on a 944 chasssis. ill do up a drawing paint. the way we did it in school was opposite: the part, then latex on top, make a wall so the plaster doesnt go on the floor, then pour in plaster and let dry, but i think the weight of the plaster might distort the hood, plus itll be heavy and hard to flip over to pull the parts out, and also be risking breaking the mold when flipping over.

kennycoulter

im not sure if it is working.

Scott at Team Harco

I'd be a little skeptical of plaster as well. Make something small and insignificant (if I may use that term) first before trying something big and important.

Thick fiberglass with a nice gel-coat outer surface is the best type of mold I have worked with. My teammates made molds from styrofoam and bondo for the bodywork on our F-SAE car many years ago. It came out OK - but it was likely good for only one part. The steel panel (skin) molds that I use for my parts work well but must be supported carefully. Due to a lack of structure they can easily flex and disrupt the integrity of the final shape.

One thing that will become obvious is surface prep. The inside of the mold - regardless of its construction - must be clean, smooth and slippery. I usually start by getting the surface as smooth as possible (sometimes even bondo over irregularities, if necessary) and then apply a couple of coats of paint to seal it. This is then wet-sanded smooth with 400 grit or finer. The final step is to apply about 10-20 coats of auto wax (allow to dry and buff between each coat). This seemingly labor intensive process assures that the part will separate from the mold when you try to remove it. I am going to experiment with a parting agent on my next project panel (the one for the article). But I will still wax the hell out of the surface first.

kennycoulter

okay its too big but maybe my description was good enough.

Promotion 951

Hello, the process is not that difficult , but in order to keep it light , the best way to make this and any other composite products, the use of vacume molding is needed , and this is where you,ll have to make a bag and also a nice mold, its most cost effective to purchase one already done, unless you are going to make more than one... Fiber glass hood and light weight fenders and bumper.