Fiberglass vs. Carbon Fiber - 986 Forum - The Community for Porsche Boxster & Cayman Owners

insite · 05-02-2007, 02:37 PM

Quote:

Originally Posted by Topless

Carbon Fiber
The same basic process as fiberglass only using carbon fiber cloth and high quality resins to get the highest tensile strength, highest strength to weight, and achieve a very rigid shape or structure.
Pros- Ultra high strength, ultra rigid, resists damage from sunlight when unpainted.
Cons- does not flex, if flexed it shatters like glass. very expensive.

i take exception to the last statement. carbon fiber can be designed to flex very well (think golf club shaft or corvette leaf springs). CF properties can be greatly varied depending on the manufacturing methods (resins, mold types, cure method, etc.).

Perfectlap · 05-02-2007, 02:43 PM

^ very true you should see my carbon fiber bicycle's rear triangle flex when out of the saddle hill climbing. These guys can do amazing things nowadays.
But ohh so expensive. I lusted after a Fondriest frame made from F1 grade CF (they had a former F1 Ferrari engineer) but they couldn't make the darn things for less than $6K and eventually went out of business. Too bad, best bike I ever owned (partially CF).

Topless · 05-02-2007, 02:44 PM

Insite,

You are right. I forgot golf shafts. My experience with CF was on racing yachts where it was chosen and designed to eliminate flex.

EPIQTodd · 05-02-2007, 02:57 PM

For a spoiler, fiberglass is just fine. No advantage for polyresin on that one.

Regarding carbon fiber and composites, I wholly disagree that it is a 'low tech' process - if done poorly, it is, but done correctly, it is VERY high tech, and difficult to do. Those who do the half-ass method of just using resin and drying in the open air are just making fiberglass with carbon fiber sheets. True carbon fiber and composites must be cured in a heated vacuum, and that is what makes good carbon fiber what it is.

yellowboxster01 · 05-02-2007, 03:35 PM

i've heard the mount holes on some of the aftermarket spoilers crack out after time. i believe there was a thread on here a couple weeks ago about it.

SC986 · 05-02-2007, 04:06 PM

If you/can you paint the carbon fiber what will the finish look like? Will you see the fiber or can it be matched in a smooth finish like the bumper?

markab986 · 05-02-2007, 04:37 PM

Quote:

Originally Posted by SC986

If you/can you paint the carbon fiber what will the finish look like? Will you see the fiber or can it be matched in a smooth finish like the bumper?

Yes, you can make a super smooth finish.
It depends on the tooling/cure process, fill & sand, and the desired finish.
Most composite components will need some sort of buildup, insert, or stiffener in the hole areas to prevent cracking.

BTW...fiberglass is a composite material too!

SC986 · 05-02-2007, 05:09 PM

Interesting. I was wondering because I love the rear diffuser bumper but have not heard good things about the fiberglass diffuser add ons.

porsche986spyder · 05-04-2007, 06:20 AM

Quote:

Originally Posted by yellowboxster01

i've heard the mount holes on some of the aftermarket spoilers crack out after time. i believe there was a thread on here a couple weeks ago about it.

Yes, what he said. If your getting a spoiler made out of Figerglass, just make sure the mounting brackets are made well and don't crack at the base. This is why I would go with Carbon Fiber, it's less prone to stress cracks. I had a spoiler on my other car that slowly began to crack because of vibrations that were sent through it every time I closed my trunk. They started right where it bolted up to the deck lid.