hooleyboy

Has anyone ever thought about getting a C/F driveshaft. i hear you can free up around 5% more of your engines power. I'm not sure what a stock Driveshaft weights but on driveshaft builder claims a C/F drive shaft with Ujoints and yoke is only 12lbs. People seem to be into the light weight pullies so why not driveshafts? One site sells them for prices ranging from 500-1400. Im sure they would have to be custom built. If you could get this for a fair price this may not be a bad mod. anyway here is the site i was looking at

http://www.pstds.com/critical_link_drive_shafts.htm

Biscuit

Interesting proposition. If a group buy was setup (and included C32's) then you could count me in!

-Rich

hooleyboy

I'm going to go to a driveline place and get my car mesuered and pass that on to a company that makes C/F drivelines just to see what kind of price it would be. My only worry would be if a rock comes up and smashes the driveline= not good. question I have is do you get 5% HP back from say the 20% you lost?

Fifth Ring

It MIGHT have the same effect as a lightened flywheel, letting the engine rev quicker; but it will not add any HP. HP doesn't get lost through a drive shaft; but it does get absorbed during acceleration by inertia. Less weight = less inertia.

e1000

lol - you know what he meant.

Biscuit

Here's a nice write up somebody did on a carbon fiber vs. steel driveshaft on a mustang.

http://www.stangpro.com/html/articles/driveshaft.htm

That's the kind of thing I like to see. Complete with before and after dyno. Surprisingly he did pick up some HP and Torque.

-Rich

mkonei

if the stocker is steel, im sure there would be a big difference. being an AMG, it is most likely aluminum already. im not sure that you would notice a big difference from alum to cf. dont worry about a rock hitting it, that wont hurt it. back in the 5.0 days, one of the first driveline mods was to ditch the steel shaft and get the Motorsport aluminum piece. the aluminum piece would rev quicker and hum less, but i couldnt quote e.t. reduction, its just been too long ago...lol


stocker is steel, my "fear no beer" magnet sticks. usually aluminum shafts are a bit larger in diameter. the trans tunnel is tight, it might be a difficult fit.

c32AMG-DTM

That IS the question... isn't it? I guess we wouldn't know until someone did it, dyno'd it, and reported back with the results. In theory, if you improve your driveline efficiency substantially (say, 25%) you would reduce the lost hp and tq from crank to wheels by a similar percentage. For example:

Stock driveline, 420 bhp, driveline losses equivalent to 19%, 420 * .81 = 340 rwhp

Modified driveline, 420 bhp, driveline losses 25% better than stock (19% * .75 = 14.25%), 420 * .8575 = 360 rwhp

In conclusion, if you could cut driveline losses from 19% to 14.25%, you could gain 20 rwhp. Hope that helps

hooleyboy

Were I'm at I'm just about out of bolt-on mods (that gain HP) that i can do other than a supercharger. It would be nice to cheat the system and steel back some of the power the car is taking away. i think I'm talking myself into my next mod. it if even can be done.

xlr8tin

Carbon fiber for a driveshaft is bad! The driveshaft spins VERY fast. The more TQ a car has the faster it will spin....

Think about it...if NASCAR still uses steel driveshafts than this is the best to use. The only other safe material for a driveshaft is aluminum.

A Carbon Fiber driveshaft may be ok for normal use on a small car like mine, but not on a high performance Benz...

If you don't believe me try it, I bet it won't last 6 months unless you drive around like a grandma.

I took a class at NASCAR Tech about drivelines and transmissions, and seen pictures and heard stories about the CF shafts.

Like I said before, Aluminum is what you want.

Biscuit

I'm 99% positive this is not true... If I had to guess the reason Nascar is stuck on steel driveline components it's because of a regulation and nothing to do with reliability. Carbon fiber drive shafts are common on high power drag applications. I can only imagine the forces they're subjected to... Nascar only generates 700-800hp.

As an example you can look at flywheel based UPS systems. The flywheels, which are carbon fiber, will spin in excess of 20,000rpm's. I can assure you that is far faster than our little driveshaft will ever see. The primary reason that companies go with a carbon fiber flywheel on these UPS's is because of safety. If they explode it just turns into a fiber mess. And don't forget the reliability these things must have. I've seen them installed in hospitals before where power interruption is absolutely unacceptable. Life expectancy on them is 20+ years at that constant speed.

xlr8tin

Hey, if you don't believe me...try it!

mkonei

theres nothing wrong with carbon fiber shafts, theyve been around for a long time. they are actually safer than a steel shaft, because they simply disintegrate instead of sending you for a pole vault ride if your front joint lets go. go look under a pro stock car, they leave at 8000+...

Biscuit

I wasn't trying to rip on you or trigger off some flame war so let me say that first. And sorry if it came off harsh. ;-)

My main point on that was just that you shouldn't use NASCAR as a baseline for your decisions. If I'm not mistaken they're still using carb's instead of fuel injection.

MJ50

interesting............

430

With your logic then Carburetors are much better than fuel injection since NASCAR uses carbs and we all know NASCAR uses only the best

SLK55R

don't the new skylines use a CF driveshaft?

hooleyboy

BTW Evosport sells carbon fiber drive shafts for BMW. ACPT.com will build you a custom C/F drive shaft for $1500 and the guy i spoke with said it could be less depending on how it hooks up to the trans and rear end


I like to think of it this way... With insanely over priced mods for out cars Most other C/F drive-shafts cost around 1k. this seems like a good deal for what you get. I mean you get a lighter drive-line that takes less power to spin than a heavier one and its safer. if our drive shafts were ever to brake it would cause a catastrophic disaster to your car causing damage to many parts. As said before ^^^ If the C/F drive shaft was to fail it would just turn to "dust" causing much less damage to your car and to you. We all know the more something weighs the harder it is to move. I think it all kinda goes along with light weight pulleys and flywheels, maybe even wheels too. we all know the lighter the wheel is the easier it is for the car to move them. I would think with a lighter drive shaft less energy would be absorbed in trying to spin it. then that savings would be passed down though the drive system and onto the wheels... were it counts. Just my take on it I could be wrong IDK.

hooleyboy

Yes they do. and thats why dyno testing on them yeild much less drive-line loss than expected. One article i read on the new GTR said the drive-line loss was much less than what was expected out of an AWD car. there take on it was that the car was just underrated when it came to crank HP. My take on it is its just not losing as much power to the wheels. could be C/F drive-shafts at work and remember that's a 4000lbs car. I think the GRT yeilds a 14% loss at the wheels and thats very good for an AWD car.

DarkXerox

Dont forget leaded gasoline...

They still use steel brake discs in NASCAR too lol.

sick430

so any chance we can get a group buy. also will this work on my car. i would measure it but its at the shop right now.

thanks
Liran

hooleyboy

That would be nice. I spoke with a drive shaft company in Cali that does C/F driveshafts and was told its all about geting them a drive shaft in there hands so they can see how it hooks up and what would be needed to make the Drive shafts. Maybe one of the Spencer's will step up and do some leg work for us as there seems to be in interest in a product that can be easily made. I would bet if say LET, VRP, or Evosport came out with a line of C/F drive shafts for Mercedes people would ****** them up. I really have no knowledge of the names of the parts of a drive shaft so i wouldn't be the best at lining this up. However i would be willing to though some loot to a person who did do the leg work to make it happen.

sick430

how long would the need the shaft for?

hooleyboy

they told me two weeks or so depending on if the parts were readily available, but after they got one made for a perticular car. I would think it would be faster.

Dr. C36

the results from lightweight flywheels and lightweight crank pulley is typically more than ltw driveshaft b/c radius plays a much greater impact than weight b/c Inertia = mass x radius^2, so its the radius that is more crucial than weight itself. With that said it still plays a factor, Carbon driveshafts can handle tons of power and supposedly they greatly reduce the amount of vibrations/harmonics felt through the chassis that most people don't even realize are b/c of the driveshaft. In addition its much safer than aluminum driveshafts (which can be downright dangerous b/c they are more prone to snapping and turning into a polevault). CF shafts simply turn back to fiber when they snap and do not hurt anything. That said... its pricey.. and not many people do it. But if you have the cash and you like to tune for efficiency as well as power, its a great way to go.