I noticed that there is a very sizeable roll of Hexcel Carbon Fiber Prepreg going on ebay right now. The price is pretty decent and although I am not nearly ready for that stage of construction so I won't be buying it, it occured to me that a beautiful carbon fiber body is just what I need!

Is this simply foolishness on my part to think that prepreg CF is even an option for full bodywork? I am curious to hear your thoughts.

Some easy reading on prepreg:
http://www.psrc.usm.edu/macrog/mpm/composit/fiber/process/prepreg.htm

Graber

I know very little about it but won't you need an autoclave (pressure cooker) within which to cure the CF?

Cheers,

James

Hmm, you could probably turn your garage into a temporary autoclave (check with boat-building trade and your local fire department).

I dunno. It seems that the CF market is controlled by a single source (though I haven't found who it is) so prices will eventually drop. If you can get a deal, fine, but right now I think CF's in the province of cost-effectiveness that can relate to whether exchange rates favor wintering in the Caribbean rather than the Mediterranean.

Another material you might want to check out is foam, to add lightness and strength, maybe cheapness, too. Just a thought, no facts.


Pete

Prepreg is standard material in motorsport for fairing and wings these days at the highest level maily due to process / part continuity and quality.

This all comes at a price. i.e. to get the stiffness performance normally a high temperature well controlled cure cycle is required along with pressure. 177dergree C and 50 psi is typical. This is why you would use an autoclave.

Companies now make reasonable good low temperature prepregs which cure at 80 degrees C so can be cooked in an oven, some even cure at 20 degrees and use a 50 postcure to get the properties up.

However, you often find that as cure temp goes down, so do the properties but the price gopes up.

To give you guidance expec to pay maybe £25/m2 minimum for material which when cured will be about 0.25mm thick.

I dont know how big your car is but given when using prepregs on 1 off parts you will need probably 50% - 100% more material than you calculate as the body surface area and its going to be at least 1.5mm thick to be stable ,then your looking at between £225 and £300 per square metre of car body.

You will also need tooling, 5 times thickness of the part is about right. If your using low temp materials you could use glass and epoxy rather than carbon.

please not my advise is my own opinion on this matter, and for what its worth its worth youd be better going for wet lay hybrid of carbon and glass, it will be strong enough, look nicer ,asthetically shiny, alot cheaper and probably lighter.

dont forget you need to store yor prepregs in a freezer!!!!

You could probably make a fiberglass body, the do a layer of CF over it, wont be as super light weigh with the ultra strong properties of true CF, but it will look the part. If you look at the auto aftermarket and all the CF products out right now, you'll see that most of the cheaper stuff is fiberglass with a layer of CF on top and bottom. Less cost same visual appeal.

Hi, just waking up in Phoenix... good morning.

I see the problem with the curing. And the price is waay out of my league, even when there is an ebay special. So that pretty much seals it off for me. No CF prepreg for the cheap bastard... Maybe when I'm rich and famous?

Derf, I built a Ferrari 250GTO replica a few years back and everyone loved it, I made the cover of Kit Car Mag with it even. But to this day I am still left empty by the thought that it was really just a poseur, a cheap glass replica on a cheap ass donor. It is the one thing that left a real sour taste in my mouth. Kinda like cheating really. That said, I think I would feel the same way about a thin 1 layer covering of CF over a glass body. It does look cool, however, IMHO it's a fake of the real thing and in the end I am hoping that every part of my new car is as real as it gets.

Graber

Oh, I agree 110%, I bought what I thought was a CF hood for my focus a while back, looked real good, but I noticed that it was kind heave for CF, then someone with an f150 backed into me in a parking lot, turned out that it was a fiberglas center with CF shell around it, and the support beams under it were the same way, and everythging was just basically glued together to look real good. After that I just saved my money and bought a fiberglass hood and had it painted.

Well, there are descent alternatives to Pre-Preg in the CF relm. If you've out Englands way, SP Systems has a nice method involving adhesive film, the reinforcement, vacuum and heat (relatively low if I remember). Can always do the wet lay up, but I'd recommend epoxy rather then polyester/viny. Or, if you want the real goods without a high price tag, I'd do a sandwich panel of 4-5oz carbon cloth (wet layup and vacuum) with a 1/4 inch foam backing and another layup over the back. Should be plenty stiff with a minimum of costly carbon layups. Probably a little sensitive to impact, but you're not supposed to use it as a ram. Cheers!

Thanks for the update Syd, hadn't heard. Carbon can have a similiar stiffness to cost of glass though if used carefully and not pre-preg. Frankly I don't think I'd use it in to many places either. But I picked up 700ft of 3in unidirection carbon tape from boeing surplus for $5 a pound. Think I'll use that to help reinforce my nose piece. Cheers!