I'm quite good with my hands, and am considering making my own carbon fiber pieces. Obviously will start with some simple stuff to get the hang of it, but I have a few questions...

1) If you're creating a mold from your OEM part, does the OEM part get "destroyed" in the process?

I know I need to layer coats of mold release wax & release agent on the OEM part so that the mold can be removed easily, but am not sure if the release wax & agent will damage the clear coat/paint/plastic finish on the OEM part.

2) I've read that interior pieces should be around 0.8-1.15mm thick. Can't find any info on how thick exterior body panels should be.

I'm planning on mostly using fiberglass to keep costs down, especially the smaller pieces that won't see much weight savings anyways. Parts that may see more pressure (hood, hatch....if I go that far...) may have more layers of CF for strength and a smaller fiberglass backing.

 

I thought about doing this a while ago, sounds real interesting. would like to see a DIY on this. goodluck man ill be checking back to see if u made progress...

 

I literally spent about 16 hours each day this weekend researching and coming up with a tools/materials list that I'll need. No clue how realistic this will be, so I'll try first with a few simple parts before I invest too much.

Regarding the first question I asked, I found the answer -- It *is* possible to create a mold of your OEM part w/o destroying it if you are extremely careful and do the following (using a hood as an example, which will be referred to as the "plug"):

1) Tape/clay off any holes in the plug -- if you leave holes, the gel/resin/fiberglass will fill it, making it very difficult if not impossible to separate the plug and the mold. Be sure to use a non-drying clay.

2) Similar to above, you need to apply clay around the edges of the plug to your working surface -- you do NOT want the gel/resin/fiberglass to get under the plug -- this will make it impossible to separate.

3) Use a mold release wax on the hood. This is different than normal wax, which has a component to remove previous layers of wax. The idea here is to build up a very glossy, hard to stick to surface on the "plug". Lay down at least 6 layers as you would normal wax -- rub it on, allow to haze, then buff off.

4) Apply PVA (Poly Vinyl Alcohol) on top of the mold release wax -- best done with a spray gun, especially for large parts. 3-4 layers, allowing it to dry in between. This will form a water soluble barrier between the plug and the mold, that, combined with the release wax will allow you to easily separate the two later on. The release wax should protect the surface of the OEM hood. If you have trouble separating the mold from the plug, you can inject water between them to dissolve the PVA. Otherwise, you can just peel the PVA off of the OEM part after you remove the mold.

5) Apply a tooling gel coating (sprayed or painted on) to the PVA after it has dried. Make sure you cover the entire surface -- the gel is what is responsible for a high quality surface/polish on the mold, that will transfer to the final part.

6) You need to wait for the gel is just right before you can start laying down the fiberglass, or whatever you are going to use for the mold -- it should be tacky to the touch, but should not come off on your fingers. If you wait too long, it will completely dry, and the fiberglass may not stick to the gel, which is bad.

Then you just continue on with the process, but at this point you can be reasonably sure the OEM part will be able to separate from the mold w/o damage to the finish. Of course if you screw up by not applying enough release wax and/or PVA....you may be destroying the finish or performing a hack job on one or both pieces trying to separate the two.

Regarding the thickness on the exterior pieces....hard to find an answer, or least a consensus answer. I've read as much as 6-8 layers of CF (or fiberglass). I've also read that on parts such as a hood, two layers of CF with either kevlar, or a foam filler is sufficiently strong! So much so, that you won't even need structural bracing on the underside! Not sure if I truly believe that, so I guess some experimentation is in order...

One thing to keep in mind though, is that regardless of how thick the piece needs to be in order to be reasonably strong, how are you going to mount it? A piece that is 1/5th the thickness of the original may not fit right, and while it may be reasonably strong in and of itself, if you're attaching it to stock mounting points, you may need to reinforce those areas even more to make sure it doesn't eventually crack/fail at those high-stress points -- especially if it's something like a hinge....

If I get to a point where I feel comfortable attempting a hood (high on my to-do list, since it's front-end weight and aftermarket hoods don't shave much), I'm thinking about not even mounting it on the OEM hinges! Not only does that create a high-stress point that is prone to cracking over repeated opening & closing of the hood, the hinges are more weight that can be shaved. Why not use hood pins in the back as well? Would make for a more durable setup, and save even more weight.

If the best aftermarket companies can make 10-12 lb hoods through use of pre-preg, or vacuum infusion, that's approximately a 12-14lb savings. Add to that the weight of the hinges & hood latch and you may be looking at near 20lbs off the front. Not bad!

Also, keep in mind that fiberglass actually weighs LESS than CF in terms of weight per amount of material. So a hood that is mostly fiberglass with maybe 1 layer of CF on top will weigh less than a 100% CF hood of the same thickness. Where CF shines is that it is lighter than fiberglass per a given level of strength. This means you don't have to use as many layers of CF to reach a given level of strength versus fiberglass. This is where the weight savings of CF come into play -- it is stronger, so you use less layers.

So you have a decision you have to make -- pay more for a thinner, lighter piece that is all/mostly CF, or pay a LOT less for a *slightly* heavier piece of the same strength level, that is also closer to OEM thickness, which may make mounting easier. The latter is the better option for most of us. Regarding the weight difference, it shouldn't be all that much -- most of the weight from the cheap aftermarket companies that are predominantly fiberglass with a layer of CF on top comes from the amount of resin that is trapped in the fiberglass, not the fact that it is mostly fiberglass.

Since an autoclave is not within my reach, pre-preg is out. The next best option is vacuum infusion of the resin, which can be done at home much more easily (I know some people make homemade autoclaves, but they can't supply the level of pressure that an industrial one can, so you're pretty much only getting the heat...I doubt the finished product in this scenario will be any better than vacuum infusion....but certainly more expensive & involving).

While most pre-preggers will swear by pre-preg, I've heard that with proper vacuum infusion, the part can be almost identical to pre-preg in terms of quality, strength, and lightness -- at least close enough that the cost difference isn't worth it unless you're a professional racing team. As an example:

stock hood (23-24lbs) -- I think?
wet layup fiberglass with CF cover (21+lbs) -- this is what most cheap aftermarket companies do...some weight even more than stock!!!
vacuum bagged (15-18lbs) -- resin is layed on as with wet layup, but excess is vacuumed out
vacuum infused (11-12 lbs) -- fabric is laid onto the mold dry, and then vacuum bagged tight. Then resin is sucked into the mold -- much less excess resin than plain vacuum bagging.
prepreg/autoclave (10-11 lbs) -- CF comes with resin "built in". CF is laid on the mold dry, and then stuck in an autoclave (pressurized oven) which causes the resin to activate and increases pressure to much higher levels than capable with plain vacuum bagging.

Don't take too much stock in the weights, especially since it can vary so much. The point is to show that there is a drastic difference between classic wet layup and vacuum infused, but a much smaller gap between vacuum infused and prepreg, with regular vacuum bagging being somewhere in the middle. Basically diminishing returns...sort of like the 80/20 rule....The last 20% amounts to 80% of the total cost. If vacuum infused is good enough for commercial aircraft and watercraft, it's good enough for me