CF: Form vs Function

[H@xtGSX]

Just a question regarding form vs function. Suppose you are going to spend the money to buy carbon fiber parts, not laminated fiberglass but 100% CF... hood, fender, hatch, etc. :

1. Is the function is serves in significantly greater weight reduction more important than the woven 3d CF fabric look?

2. If you had a CF panel, would you paint it? (for the sleeper look, security, whatever...)

I am thinking that people who buy real F1 style 100% CF parts are buying it mainly for the weight reduction, and if it incorporates the uniform fabric look on the surface, it's of secondary interest only. Are you of the same opinion, or is the fabric a "must have" feature for CF parts?

 

[LiquidX]

If you buy CF then it should mainly be for the weight reduction. I know a lot of people get it for the looks which they would be better off getting an over-lay.

Personally I would paint it to match. Just do not get CF doors on a DD.

 

[Bud92gsx]

I got my hood cause I liked the look of Cf..The weight reduction on a hood alone is not really worth it, unless you go with more CF parts..

I Now cannot work under the hood on a windy day..Where before I could..But ohh well...

I would never paint it cause I like the look..But that's just me..

 

[T is for TURBO]

Just do not get CF doors on a DD.

Saftey factor I assume?

 

[snowborder714]

Yes. CF doors are pretty much just the outer shell and contain none of the safety/structural innards that a normal door does. People get them for weight reduction and that is a huge section of weight that is not needed. If you want CF doors, you better have a cage with door bars.

 

[92AWDHX40]

I guess ill let my buddy know about that hes so wanting cf doors on his spyder.

 

[Awdspyderman]

yea i thought about putting CF doors on my spyder(LOOK UP CFECLIPSE HIS SPYDER IS THE S##T)but ill be happy to do front fenders,hood,and if i can get CFECLIPSE to make a carbon fiber spyder trunk and spoiler for the same amount i just may do that instead of the doors. I'm doing it for the wieght and i love the look of carbon fiber with a white shell it just looks f*##ING SICK. To each is own i guess=)

 

[silicosys4]

IMO carbon fiber is pure function, it just happens to look nice
I see threads detailing peoples fitment woes...thats what vinyl wraps are for.
From what I've read, if its real CF and not an overlay, unless extra special care was taken (even more $) a correctly done CF part will probably have inconsistencies with the weave because of how it sits in the mold, how its compressed while vacuum sealing and curing, etc...again, that's what wraps are for if that concerns you.
I'd leave it unpainted for the looks, If I thought I could trust the clearcoat. (Paint adds weight, )

 

[H@xtGSX]

I was asking mainly because I make CF/Aramid parts every so often for a mine I work for, and I came across a technique that *can* reduce cost quite a bit without sacrificing a noticeable amount of strength while still keeping the weight extremely low. We have tried it, and it works quite well. It's just not as pretty.

There's a possibility of manufacturing the parts people have been asking for, as 100% CF pieces, but not at F1 racing prices. Very few of us would be able to afford that. One of the problems is that t700/aerospace grade cloth in several weaves is becoming increasingly hard to purchase in smaller than 100 yard quantities, and I'm not in a financial position to drop $2800 for a roll.

I normally don't like using anything less than aerospace CF because the flexural modulus in commercial grade CF cloth is a ballpark guess, at best. If I made someone other than myself a part, I want the knowledge that the part is as strong as it possibly needs to be and isn't going to fail catastrophically and hurt/damage anyone or anything. That way I can sleep at night, and the people who use them are confident in the safety and quality of the part. In reality though, the strength of both aerospace and commercial CF is usually more than strong enough for most automotive applications. It's mainly just for my peace of mind.

The catch is that the "pretty" cloth CF look would be extra, not necessary. I can laminate it on as a surface layer on a few if it's something the person really has to have, but for automotive use, it's unnecessary.

If that isn't a major problem with the people potentially using the parts, then I'll continue setting up a few production molds and rigging up a series vacuum pump.

And to address the statement above:

Fit problems are more a result of using lower grades of epoxy. Some epoxies will shink a tiny bit OR can absorb more water than others. I generally stick to ASTM tested structural epoxy with a known shrink rate, which should be miniscule. When I vac a laminate something like a ballistic equipment guard, I leave a couple inches of surface for fiber outside of the mold lip, so final cut size is adjustable if needed.

Another factor is cure. If cured at a temperature under the epoxy's moment of fluidity while still contained under the vacuum used to form it, it will be exact to the mold used if stored properly after being demolded. This is assuming that the part is made with an appropriate resin though.

Finally, all carbon fiber matrixes have a little expansion/contraction that can be noticable along tight body lines, which can be minimized through epoxy type, but it's just an aspect of the material that you have to accept for the weight reduction. I personally don't notice it unless it's REALLY hot or cold outside, and it will normalize once the engine heats up.

As for the inconsistancies, you are correct. The widest roll of CF that I've heard of is 60" wide, and it's not cheap. That generally means the fabricator will have to use a couple pieces from a 50" or 42" roll to form something real wide, like a hood. If they don't bother matching the weave at the intersection and super gluing it in place so the vacuum bag doesn't move it much, there's an obvious visual change in pattern. Even gluing the join line doesn't always work.

 

[silicosys4]

If you can produce strong CF parts that fit well, I could care less about inconsistencies in the weave, and I'm sure many others would agree. I'm about to pony up big $'s for a chaser CF convertible hardtop, and its got all sorts of weave inconsistencies, which I have no problem with as it weighs half as much as the fiberglass version, and I know fitment isn't an issue (been on another car already)
Peoples biggest gripes that I've heard with CF is fitment past the point of being cosmetic, to where permanent modifications has to be done to the car to make it work.

 

[Fotowntalon]

I get CF for weight reduction mainly. I also love the look, but I have mine painted, well painted with a clear coat/black gloss mix, so on certain angles it looks a deep dark cf/ others it looks stick coloring

Saftey factor I assume?

This is a misconception by most, CF is actually more safe than steel. One of the reasons (beyond weight) that F1, and Indy car drivers are putting more and more CF in there cars. CF actually absorbs the energy in a crash and breaks away, where as steel crumples and keeps transferring the blow to other parts of the vehicle, and the driver.

Most people would be scared of having it on a DD because because of being scared of other jerks getting there doors and etc (or by having the misconception on safety)

 

[Blurred Talon]

I get CF for weight reduction mainly. I also love the look, but I have mine painted, well painted with a clear coat/black gloss mix, so on certain angles it looks a deep dark cf/ others it looks stick coloring



This is a misconception by most, CF is actually more safe than steel. One of the reasons (beyond weight) that F1, and Indy car drivers are putting more and more CF in there cars. CF actually absorbs the energy in a crash and breaks away, where as steel crumples and keeps transferring the blow to other parts of the vehicle, and the driver.

Most people would be scared of having it on a DD because because of being scared of other jerks getting there doors and etc (or by having the misconception on safety)

CF is not going to take a hit anything like a steel door will. Yes CF is strong but the whole point of those impact bars is to transfer energy away from the driver.

I personally like CF for the weight reduction aspect. It does look good on some colors; however other colors, it needs to be painted.

 

[Ludachris]

I've been wanting a true carbon fiber hood and hatch for my GSX for a while (and fenders, and doors, and dash, etc). Instead, I have a hood and hatch that consists of a fiberglass shell with a CF top layer like everyone else. And I'd like the option to get them without the thick clear coating so that I don't have to sand it down by hand to paint it. I don't care of the weave looks perfect because I want to paint it. So long as it's strong and fits right, I'd absolutely love to see some less expensive options out there that can save just as much weight. Maybe then we'd see CF fenders for all DSMs, along with all kinds of other parts.

On a side note, I edited your post so that it doesn't violate our commercial posting policy. We don't want people posting threads for market feedback who aren't a Supporting Vendor - or at the very least, a Supporting Freelancer.

 

[Fotowntalon]

Actually BlurredTalon, CF is stronger than steel, and I would prefer that over steel in an accident. Now if you are talking in an accident where roll bars are required.. well that's why the roll bars are required.

 

[Ludachris]

Actually BlurredTalon, CF is stronger than steel, and I would prefer that over steel in an accident. Now if you are talking in an accident where roll bars are required.. well that's why the roll bars are required.

Not for doors with no crash beams. CF shatters and wouldn't protect your legs well.

 

[silicosys4]

Actually BlurredTalon, CF is stronger than steel, and I would prefer that over steel in an accident. Now if you are talking in an accident where roll bars are required.. well that's why the roll bars are required.

In my uneducated brain, I'll take a stab at this one just for giggles, and to promote the argument,

I see the differences come in how each dissipates energy. (would love to hear a composites expert chime in here) Steel dissipates energy by deforming and displacing, while CF dissipates energy by shattering and fragmenting. While each might stand the same amount of energy before breaking, the method of breakage is why you don't see CF rollbars. Steel dissipates energy in a much more linear fashion, by bending in a predictable way in predictable directions in predictable amounts depending on force. CF will shatter in an unpredictable manner into splinters that no longer retain any crash absorbing properties once the initial splinter/fragmenting/impact has happened.

So I see CF being as strong as steel, but not what you'd want in an impact, as once it goes, where steel would bend and absorb/dissipate energy, and even bent still offer impact resistance (multiple impact events...like a car rolling/flipping multiple times) the CF will dissipate it through a burst of splintering and fragmenting, and then offer no additional impact resistance. (in a roll, take the first hit, absorbing the impact by shattering/fragmenting, then each subsequent rollover impact is on your face)

manufacturers of CF monococque chassis use energy absorbing honeycomb cells to absorb energy more linearly, to avoid the shattering effect...good luck finding dsm CF doors that have honeycomb cells, ....I'd still keep my detroit steel door impact bar in a cf door if it were a street car with no cage.

 

[AG 305]

i think its more of a function thing then a form. CF looks to ricey to me but hey thats just me. if i myself absolutely needed CF parts ill probably paint over it.

I Now cannot work under the hood on a windy day..Where before I could..But ohh well...

lool just take the hood off. i know its a drag but itll be better especially if youre gonna be working on it for awhile

 

[MidShipCivic]

I'm going to just make this clear the parts that you commonly see aren't 100% carbon they are an carbon overlay on top of black pigmented fiberglass. Real carbon parts are worth more than a used 1g a hood made from real carbon and sold retail could be 4 to 5k and would be light as a feather and stiffer than anything.

For example a (dry carbon) trunk for an evo at mininum is 1500.

A dry carbon hood for an evo X is 1900 and weighs 11 lbs.

 

[Bud92gsx]

But really what's the difference between CF on top of fiberglass and all CF..Maybe a couple ounces as far as weight is concerned..

I'm happy with that..As long as it's functional..And not oober expensive I can deal with half and half.

I would like to see CF fenders fora 1g..

 

[MidShipCivic]

But really what's the difference between CF on top of fiberglass and all CF..Maybe a couple ounces as far as weight is concerned..

I'm happy with that..As long as it's functional..And not oober expensive I can deal with half and half.

I would like to see CF fenders fora 1g..

It is not a few ounces.

 

[9!'clipseDOHC]

If I were to buy a carbon fiber hood and/or hatch I would paint it to match the rest of the car. For me it would be only for weight reduction. Therefore I would be interested in what you are talking about, depending on the price of course. My other option would be to buy a used one since I am going to be removing the clear and painting it anyway.

 

[Bud92gsx]

It is not a few ounces.

It's not just a few ounces huh..Well it can't be all that much cause fiberglass is also not very heavy..Well maybe the resin is, but the resin on top of the CF is also probably kinda heavy as well..


I like the look of the CF so I might not paint it..Well maybe fenders I might paint..Ok doors I would probably paint too..But hatch and hood I would not..

 

[camsmurdered2g]

The only time I would ever paint CF is if it stuck out like a sore thumb and looked out of place. The overall weight reduction is always good, whether it is 5lbs or 500lbs, a little here and there add up to a lot.

 

[MidShipCivic]

It's not just a few ounces huh..Well it can't be all that much cause fiberglass is also not very heavy..Well maybe the resin is, but the resin on top of the CF is also probably kinda heavy as well..


I like the look of the CF so I might not paint it..Well maybe fenders I might paint..Ok doors I would probably paint too..But hatch and hood I would not..

Are you a composite hobbyist ? IT's not a few ounces if this were true pretty much every motorsport that made use of carbon composite would save tons on their budget not bothering with a ''couple of ounces'' it's a pound(s) difference.

That wavy mass produced hood with an overlay with cheap resin that will fade in some long term UV is no match for a thin stiff hood of dry carbon.

Where a regular seibon hood ''faux carbon'' is 17lbs a dry version is 5lbs that is the shear difference.

 

[Bud92gsx]

That wavy mass produced hood with an overlay with cheap resin that will fade in some long term UV is no match for a thin stiff hood of dry carbon.

Where a regular seibon hood ''faux carbon'' is 17lbs a dry version is 5lbs that is the shear difference.

Yeah I know about the crappy resin they use..Which is really too bad..I have had mine out in the sun for 2 years now and it's just starting to need some work..

Really 17lbs vs 5 lbs..That is a hell of a difference..Thanks for the info..

But you also said the price would be outragous for all CF vs the CF overlay on top of fiberglass..

So I guess if you have deep pockets you can get true CF and not have to worry about the price..But for most of us broke dsmers, the overlay is good enough..