Fiberglass versus carbon fiber question
07-08-2011, 09:28 AM
#1
Launching!
Thread Starter
Join Date: Jan 2008
Location: MN
Posts: 248
Likes: 0
Received 0 Likes
on
0 Posts
Fiberglass versus carbon fiber question I was wondering typically how think are fiberglass hoods and fender and also the thickness of carbon fiber. Also what's the weight difference between two identical hoods? Just seeing if carbon fiber is worth the money or not. These are for a drag truck so lite weight parts will be used. I'm building a 91 GMC Sierra and with the exception of a one piece front end no one makes fiberglass fenders or doors for this model. So i'm in the process of making the molds and going to make my own parts. Thanks
Last edited by deion82; 07-08-2011 at 09:36 AM.
07-08-2011, 11:07 AM
#2
On The Tree
iTrader: (7)
Join Date: Jan 2010
Location: Keller, Texas
Posts: 153
Likes: 0
Received 0 Likes
on
0 Posts
IDK, all i really see on drag cars is fiberglass. Most of the time when i see carbon is on high end cars and ricers, I do like the carbon fiber idea but fiberglass is much cheaper to make.
07-08-2011, 11:35 AM
#3
It's really simple, you see alot more fiberglass on drag cars because it's cheaper, especially for people trying to race on a budget. Real carbon fiber is a lot stronger than 'glass but also much more expensive, that's the reason you see it more on high end cars. IMO, if the budget allows, use carbon fiber, if the budget says to go cheap, go 'glass.
07-11-2011, 12:46 AM
#4
It's really simple, you see alot more fiberglass on drag cars because it's cheaper, especially for people trying to race on a budget. Real carbon fiber is a lot stronger than 'glass but also much more expensive, that's the reason you see it more on high end cars. IMO, if the budget allows, use carbon fiber, if the budget says to go cheap, go 'glass.
07-15-2011, 10:40 PM
#5
Carbon fiber is stronger in the same configuration, it's also _MUCH_ more brittle. Yes, high end (even race cars like F1) run carbon fiber parts, but they are also reenforced with kevlar or 'glass at stress points. When you see a F1 car smack into something and then they talk about how strong the carbon tub is, it's really not the carbon fiber, that disintegrated on impact (typically you'll see a cloud of dust) and the parts that are still holding together are kevlar reinforcements.
If money is no object (like an F1 or high end aircraft budget, remember, this is one off, not a production car where you save some by making many of the same part), then go for it, use carbon and reenforce it at the stress points. To do it right you'll need an autclave (heat and vacuum) and probably use pre-peg, and you'll end up saving a pound or 2. Use carbon fiber cloth and standard lay up techniques and you'll end up with a piece either heavier or weaker than a 'glass part for more $$$
Unless you have the "right stuff" sitting around or cubic dollars to spend, you won't come out ahead using carbon fiber
If money is no object (like an F1 or high end aircraft budget, remember, this is one off, not a production car where you save some by making many of the same part), then go for it, use carbon and reenforce it at the stress points. To do it right you'll need an autclave (heat and vacuum) and probably use pre-peg, and you'll end up saving a pound or 2. Use carbon fiber cloth and standard lay up techniques and you'll end up with a piece either heavier or weaker than a 'glass part for more $$$
Unless you have the "right stuff" sitting around or cubic dollars to spend, you won't come out ahead using carbon fiber
07-16-2011, 06:24 PM
#7
Carbon is very strong and very stiff. It doesn't turn into a cloud of dust upon impact. The materal is engineered specifically for it's application by fiber orientation, resin, and fiber density. It can also be combined with other fibers for different uses. It's a great material to work with but it can go from pricey to really expensive. There's a whole lot of good and bad info on this, if someone hasn't actually done any real work with it they usually don't know much about it.
Trending Topics
07-19-2011, 11:18 PM
#8
Launching!
Thread Starter
Join Date: Jan 2008
Location: MN
Posts: 248
Likes: 0
Received 0 Likes
on
0 Posts
Well the 1st mold i made didn't turn out to my liking so i sent it to the trash. I'm now working on second mold and both are made of fiberglass. Once i get a good mold i will take pictures and post for sure with all details. I should have kept the 1st mold as it was something to work with but had alot of pitting on the body line. I went and bought 5 yards of pure 2x2 twill 3k carbon fiber which should be enough for a fender if not two fenders. I'll have to wait and see until i actually start the process of making a fender. I also bought some uni-directional 12K carbon fiber. My thought is to use the 2x2 twill for the outer layer and then use the 12k uni-directional for added layers for strenght and support. I'm out on the road for work so it's killing me not to be able to work on this but i will post pictures through the entire process. Also will be using an System 2000 epoxy resin.
07-19-2011, 11:20 PM
#9
Launching!
Thread Starter
Join Date: Jan 2008
Location: MN
Posts: 248
Likes: 0
Received 0 Likes
on
0 Posts
What about the carbon fiber/ kevlar hybrids. I'm thinking of using that for the hood to get the added strenght for such a large piece? Any thoughts on that or input?
07-19-2011, 11:31 PM
#10
Launching!
Thread Starter
Join Date: Jan 2008
Location: MN
Posts: 248
Likes: 0
Received 0 Likes
on
0 Posts
The manufacturer of the carbn fiber did say that vacuum bagging is the prefered method but they did say with the newer epoxy resins that the old lay up technique is being utilized all other for the fact of the cost of vacuum bagging with very good results. Beside's i'm not going to wreck the truck that they are going on so who cares. ha-ha just kidding on that comment. I am trying to make these correctly in the event i do crash. I'm really undecided on what to do with the doors. I'm almost thinking using the carbon fiber/ kevlar hybrid fabrics and not skimping on the material as i think i can still save a bundle of weight with a heavy duty c/f door and lexan window over stock.
07-31-2011, 11:28 AM
#13
you're mistaken if you think that you're going to get crash protection from any light weight, non structural body parts and last i looked the hybrids are a waste of time and money for non structural stuff. Make them out of as thin a layup as gets a rigid enough piece for you to be happy with (the thinner it is the more it looks like glass and less it looks like the original because of they way it will flex...), and if they're really that thin then you might want to reenforce mounting points with extra layups or other fibers and let it eat.... but like I already said, without spending some $$$ on CF specific process I doubt that you'll save any weight over just using 'glass.
FWIW, do a search over at the corral, there is a guy there that replaced most of the body of his mustang with custom carbon fiber parts, I remember a lot of pics of it there also...
FWIW, do a search over at the corral, there is a guy there that replaced most of the body of his mustang with custom carbon fiber parts, I remember a lot of pics of it there also...
08-28-2011, 02:45 PM
#15
you should invest in a vacuum pump you can get an affordable one from anywhere
dont use epoxy because it takes months to fully cure without autoclave
use vinylester 470-300 and 411-350 resins
only use twill when you want to see the fibers it is more decorative instead use universal weave its cheaper
470-300 in the centre of the part and 411-350 around the edges
on the hood your gonna want to use either cor-mat or nomex honeycomb for stiffness stick with the cor-mat for your fisrt try
nomex is harder to work with and regires many more steps to get it right
layup:
wax mold with gold mold release wax
spray mold with "green" PVA onto mold surface
spray gelcoat onto mold surface and allow to cure
lightly sand gelcoat to give mechanical adhesion
wet out gelcoat with 470 and 411 around edges laydown first coat of universal weave and saturate.use cut strips about 5" wide around outer edge
second layer more resin same process
third layer use either S or E glass
then laydown your cor-mat and saturate dont use roller on cor-mat will damage use plastic bondo spreader to move resin around
then lay last layer of carbon down make sure you pay close attention to air pockets around cor-mat ridge use "air-dry" wax in the resin so you can sand afterwards
then lay down peel ply then breather then bagging film use 2 sided tape around edges of mold to hold bagging film use 2-3 vavles on hood in 2 corners and centre at front hook up vacuum pump and watch the miracle start to happen. keep an eye on the guage and make sure you at least have 25" of mercury walk away and come back in the morning to open your present
ive left out a couple small things to keep the post in line but if you do some research youll get it figured have fun and be prepared to need help to lift your 7 lb hood hehe
Beau
Beaudacious Fabrication
dont use epoxy because it takes months to fully cure without autoclave
use vinylester 470-300 and 411-350 resins
only use twill when you want to see the fibers it is more decorative instead use universal weave its cheaper
470-300 in the centre of the part and 411-350 around the edges
on the hood your gonna want to use either cor-mat or nomex honeycomb for stiffness stick with the cor-mat for your fisrt try
nomex is harder to work with and regires many more steps to get it right
layup:
wax mold with gold mold release wax
spray mold with "green" PVA onto mold surface
spray gelcoat onto mold surface and allow to cure
lightly sand gelcoat to give mechanical adhesion
wet out gelcoat with 470 and 411 around edges laydown first coat of universal weave and saturate.use cut strips about 5" wide around outer edge
second layer more resin same process
third layer use either S or E glass
then laydown your cor-mat and saturate dont use roller on cor-mat will damage use plastic bondo spreader to move resin around
then lay last layer of carbon down make sure you pay close attention to air pockets around cor-mat ridge use "air-dry" wax in the resin so you can sand afterwards
then lay down peel ply then breather then bagging film use 2 sided tape around edges of mold to hold bagging film use 2-3 vavles on hood in 2 corners and centre at front hook up vacuum pump and watch the miracle start to happen. keep an eye on the guage and make sure you at least have 25" of mercury walk away and come back in the morning to open your present
ive left out a couple small things to keep the post in line but if you do some research youll get it figured have fun and be prepared to need help to lift your 7 lb hood hehe
Beau
Beaudacious Fabrication
09-06-2011, 07:53 AM
#16
TECH Enthusiast
iTrader: (1)
Join Date: Dec 2002
Location: Long Island NY
Posts: 530
Likes: 0
Received 0 Likes
on
0 Posts
there is a lot of misinformation on here. you'll find a lot of the info you need by reading at racingcomposites.com and werksbergs composites forum. the info is mostly all there, you just got to read through the old posts/do searches.
09-22-2011, 02:23 AM
#17
It takes a lot of engineering and process control to make carbonfiber worth using. Your not going to wetlay anything "lightweight" just by using carbon. Even under vacuum more than half the weight of something wetlayed is resin so it's all but pointless.
Racing and aerospace use prepreg for this reason but you should just make something pretty like orange88ls1s-dime said. Except don't bother using s glass (no offense orange)
Racing and aerospace use prepreg for this reason but you should just make something pretty like orange88ls1s-dime said. Except don't bother using s glass (no offense orange)
