Carbon Fiber Bodywork

Sooooooo, here it goes Last year while ripping up the 405, I lost my left side cover. I was kinda bummed, but it had a broken tab and that helped it to its demise. Decent condition OEM covers cost a few bucks more than usually want to pay at the time, so I was looking at the aftermarket solution. Plastic sidecovers that mount using screws......hey, it's garaunteed not to fly off :laugh:

So, back in my bodyshop days I had some training in fiberglass.....not alot mind you, but I was exposed. Later down the road I had to patch up an RF900 body I shattered and I learned a little more. Then I wound up with a fiberglass body kit for my 914, and no instructions. So, I researched a TON and figured out how to install it myself, learning quite a bit more along the way (and learning what HACKS the body kit manufaturer was). Then I started screwing around with carbon fiber, since it's the same process, just more expensive, prettier fabric :laugh: I never did anything cool, just some flat panels. And that brings us to the present day, where I decided to make some side covers out of carbon fiber! There are some processes and materials involved that I do not have any expereince with, so this will ultimately be a learning experience for me, but I'm excited to figure it out.

Now, first things first, as far as I can tell, all quality carbon fiber laminates are vacuum bagged to help insure the lightest, most compact part that can be obtained. The removal of most of the atmosphere around the lay up creates an ungodly amount of force during curing. We'll get into specific numbers later. I needed a vacuum pump I looked at hundreds of pumps and researched the different types for efficiency and noise. I settled on an inexpensive ($50) ebay item, a Gast rotary vane pump. Older style, reliable and made in the USA It pulls an honest 26.5 inches of mercury on a layup and with a filter jar attatched to the exhaust makes a very livable humming noise

Now, while I have done fiberglass and carbon fiber layups without a vacuum pump, this is my first time with one, so I wanted to run some experiments on a flat panel first, just to see how it'll work. If I can't make it work on a flat panel, how can I expect it to work in a side cover mold?

My flat panel of choice is a simple piece of 3/4" aluminum plate, with one side polished.

After cleaning up the plate on the buffing wheel, I wiped it down with acetone.

For my first layup I coated the aluminum with PVA or poly vinyl alchohol. This is a release agent that forms a super thin plastic sheet on whatever you spray it on. the prefered method of application is to spray, but it can be applied with a brush.

The nice thing about PVA is it's water soluable, so if it soesn't peel off your part, you can wash it off. So the first coat is a mist coat, followed by 2 medium wet coats. The finished coating looks like this:

You may or may not be able to tell the slightly greenish tint there, compared to the straight polished pic. One thing I do not like about spraying PVA is that you practicaly need a paint booth to keep it clean, otherwise dirt (there is a bug in this coat) and crap get trapped in the PVA and those surface imperfections get transfered to your molded part

I also had to set up my vacuum pump, as well as buy a few new parts to make it all work! The first was of course, the vacuum line. I went to the local hardware store a bought 3/8" o.d. polyethylene line for $.19 a foot. While I was there, I got a T fitting and a small valve so I could control the vacuum amount and hook up a gauge.

I also needed a bag connector, which I got from Fiberglass Supply
www.fiberglasssupply.com/Product_Catalog...3rj6ICFQ4BiQodLkF1bQ
Incidently, I also bought my bagging film, sealant tape and perforated release film from these guys...great prices

The bag connector is a sandwich deal with a silicone gasket, 1/4 turn lock.

The vacuum pump came with a quick connect fitting for the vacuum line, and I put this on the bag connector. That way I don't have a cumbersome hose attatched to the fitting while trying to seal up the bag :blink:

The only thing I would do different here is to put a 90 deg elbow on the bag connector so the vacuum hose sticks out to the side.

Our matrix being used is a 2 part epoxy resin mixed at 3 parts resin to 1 part activator. The material I have here is supplied by US Composites www.uscomposites.com/ , and is their standard thin epoxy resin:

Next to the epoxy is a $10 oz/gm scale I got somewhere off the internet and a standard issue plastic party cup. I measure the resin and hardener by weight (I prefer the accuracy over bottle pumps) and the plastic cups are WAY cheaper than the mixing cups you buy for $1 each from the supply stores! My mixing sticks are a bundle of window and door shims I got at the hardware store for a couple bucks. Break 'em in half then split 'em in half and each shim makes four mixing sticks

Ok, thats enough for now I'll finish getting this brought up to speed tomorrow. I gotta go turn off the vacuum pump from attempt #2 and get some sleeeeeeeeeep! :laugh:

This is the resin mixed. Once layed out thin in a layup, the yellow color isn't as noticable. But with black carbon fiber, who's inspecting for perfect clarity of the resin? I'll probably splurge on a clear resin when I do the final parts anyway though. I'll need to order more epoxy anyway.

Adam, when you get ready to do the real thing, go to that website that I gave you. All of their epoxy is clear. You could also use west systems from West Marine, but that stuff is expensive.

Awesome thread. It think we'll all learn from this one.

Good write up. Roy

Thanks Josh, Roy- So this first laminate is 4 layers of fiberglass, 2 layers on each side of a core material. In this case, I am experimenting with a sheet of closed cell polyurethane foam I got at the local craft store. The same craft store also supplied my polyester bleader/breather material. In hind sight, I'll order breather material from a composite supplier next. It's half the price per yard than at the fabric/craft store :blink: Getting started with the first two layers, I place each layer down individually and pour some resin over it. I then work the resin around with a standard body filler squeege