Gears & Axles - Carbon Fiber
09-16-2007, 01:42 PM
Is anyone using CF for Axles,driveshaft ect.. is there a big diffrence from using chromemoly
is the gain vs price worth it?
Has it been used for valves,rods ect..
09-16-2007, 02:37 PM
they use carbon fiber mostly for body pieces, but ACPT (I think is the name) makes a carbon fiber driveshaft. its a small gain, but its the safety factor that makes it worth it.
09-16-2007, 02:51 PM
Actually the only drawback of carbon fiber for those rotational applications is price. They have a higher critical speed, the speed of rotation at which the shaft will explode from vibration, and are alot stronger than chromoly. They also are more lightweight, which frees up a bit of hp.
Say you have a steel driveshaft, 4.11 rear, and trap 135 in the quarter. The steel shaft might be spinning so much, due to high speed, and low gear ratio, that it might hit it's critical speed and explode. This is dangerous, and a good application for a CF shaft.
I don't think it is HARD enough to deal with stresses of internal engine components, and I don't know a whole lot about CF, but there are a few companies that make CF driveshafts. They are about $800 and they are the last one you'll need.
Hope this helps. :)
09-16-2007, 03:12 PM
yea i know it´s ideal for driveshafts for vibrations dampening ect.. but any info on axles and other mechanical parts
09-16-2007, 04:42 PM
Has it been used for valves,rods ect..
Here's a test nasa did on carbon pistons in an internal combustion engine:
http://ntrs.nasa.gov/search.jsp?R=306414&id=2&qs=Ntt%3Dcarbon%257Cpiston%257Cinternal%26Ntk%3Dal l%7Call%7Call%26Ntx%3Dmode%2520matchall%7Cmode%252 0matchall%7Cmode%2520matchall%26N%3D0%26Ns%3DHarve stDate%257c1
There are a lot of other tests with different uses of carbon fiber but they're not available online for free. Search around that site some and see what you can find?
edit: Just found this on google. http://www.techbriefs.com/index.php?option=com_staticxt&staticfile=Briefs/Aug02/LAR15094.html Very interesting.
09-16-2007, 05:02 PM
I'm sure CF could be used in axles and things like that, but I just don't know of any companies that make such a product.
09-19-2007, 12:24 AM
I think that the biggest advantage is the overall weight loss. Since the diameter of driveshafts and axles is so small, the rotational mass is not as much of a problem like it can be in a flywheel or wheels and tires. Stock drive shafts are usually pretty heavy, and loosing weight in axles is good for reducing sprung weight for the suspension, but power gains are probably pretty small.
So, if you want more power, it wont be worth the money. If you are looking to drop some weight it might be.
(I'm still a bit of an amature on this stuff so if I'm wrong, please correct me)
and to answer your question, I don't know where you can get them
I hope this helps, and sorry for the length
09-22-2007, 03:42 PM
Rotational weight and vibration dampening is a huge power factor and it lowers the stress factor on other parts
I´m rather asking why it is not used more commonly and in other parts like clutches,axles,brakes(rotors and pads) ect.. and trying to start a discussion :)
Talking about brakes and clutches,are any aftermarket clutches made of silicone Carbite or what are they made off?
09-23-2007, 10:50 PM
My only experience with CF parts has been on a 1970 vette. It had CF axles, but now runs steel. The CF part of the axles NEVER broke, but the aluminum U-joints kept wringing apart. I have heard of problems with CF driveshafts in road use from rocks chipping them, resulting in failure. Also, once when a u-joint broke, it took out the CF rear monoleaf as part of the resulting damage. I suppose that to make a long story short, carbon fiber is extremely lightweight and strong, but can only be as strong as it's weakest link. If my friend had steel u-joints on his CF axles, they would probably still be on the car.
09-24-2007, 12:25 AM
CF composites are excellent when used in the proper application.
The "stoutness" of the composite can be likened to these following tidbits:
1) Directionality of fibers, all fibers unilateral? or laid in layers on different angles? Unilateral is BAD unless tension is in that direction solely. Multi directional= GOOD
2) How many layers? More the merrier, and the more directions, the better
3) Length of fibers. The longer the fiber, the better. Short fibers are not strong.
4) What epoxy is used? This is a critical factor, the epoxy does have a small amount of strength, but it's mainly to hold the fibers and provide protections like UV and whatnot.
I have it for my driveshaft, and it's really more of a safety factor. The failure modes become more important than the strength honestly.
CF composites get their strength from the direction of the fiber, so a weighty rock flung perpendicular to the composite can weaken or cause failure in the part.
As for rotors and pads, there are applications of such, Carbon ceramic brakes, awesome but expensive. This is just CF laid in ceramics.
It can be used for axles, but once again, your moving the fail points to somewhere else. This can be good or bad depending on how you want parts to fail and in what manner.
As for engine, there are patents on a carbon fiber composite based engine block
This patent could be improved a bit however, and the technology was explored back in the 80's. Carbon-carbon oxidizes, it would necessitate an entirely new realm of pistons, rods, cranks, machining, etc. etc, because of thermal induced incompatibilities in an unknown end-user application. Not to mention different maching requirements and tools. Much too pricey.
I believe in the 80's Toyota experimented with a mostly carbon fiber composite engine. It was awesome, but way too expensive and there would be problems having it as a production engine. I'd have to check my textbooks.