Japanimal

Carbon Fiber is probably a bit too pricey as far as the (Perf increase/$) ratio goes but aluminum shafts aren't all that expensive. Would seem like a logical upgrade to go along with the T/C. God forbid we lightened these 3800lb Lexus's up a lil bit. The only downside I can think of is dealers giving grief on rear end/trans warranty and a possibility of some vibration at 130mph+. Carbon wouldnt have that problem, but how often do you guys drive at 130+??.....er...nevermind, don't wanna know.

hubbard316

What kinda HP & TQ numbers are we looking to gain from this setup?

Japanimal

How much HP/TQ gain at the rear wheels can we gain through increased efficiency?? Good question.... I am assuming that drive line loss for the GS 300/400 & LS 400 is somewhere in the 15-20% range. Let's say that a GS4 that is rated at 300hp at the crank has 17% drive line loss and puts out 249hp to the ground. I would imagine you would gain somewhere between 10-15hp/tq at the rear wheels. The boys at Moser Engineering would likely be able to give some real answers.. It may not sound like a lot but consider that if you gain 14hp to the rear wheels that is more like adding and intake that adds 17hp to the engine. Also (I think?) the gain would be throughout the entire rpm range. I am by all accounts not an expert on the subject...so I could be way too optimistic on those numbers.

v300

Japanimal,

I think the majority of the drive lost would occur in the transmission itself. By the way, an aluminum driveshaft is lighter and more durable than a carbon fiber driveshaft (designed for daily driving less race). If you are seriously considering getting a driveshaft let me know. By the way, you might as well get rid of the cheesy rubber couplers and use steel/aluminum U-joints between tranny to driveshaft and driveshaft to differential.

Japanimal

Last time I chechekd Carbon Fiber was lighter than aluminum and stronger as well. Carbon Fiber has better dampening properties than metal shafts as well...so better driveability.

Japanimal

Well the advantages of CF and alluminum drive shafts is their max critical speed, meaning a heavy steel driveshaft will start to bow in the middle while spinning fast, alluminum has less mass and therefor has a higher critical speed before balance, and CF has the least mass of all and therefor has the highest critical speed.

Alluminum and CF are actually not as strong as steel of the same diameter, but under sustained high speed the heavy mass of a steel driveshaft will cause a bowing type effect in the middle, the longer the shaft the greater this effect and the more vibration you will feel. Since the other driveshafts have less overall mass this effect is greatly reduced and the driveshaft can be spun at much higher speeds without any problems.

So is there an advantage to going with an alluminum or CF driveshaft, hard to answer, I've seen broken CF driveshafts quoted to be unbreakable, alluminum drive shafts that look like a twizler at the yoke, steel shafts snapped at the yoke, so they all can be broken just as easy as the next without a doubt.

Steel is the heaviest but offers the greatest strenght per size shaft, allumium drive shafts of a larger diameter have proven to be as strong as smaller diameter steel shafts, CF is best reserved for indy racing, the only advantage it has it low mass which gives it a very high critical speed which might become an issue while trying to go 200mph, they have to be larger in diameter to be of equal strength as steel shafts as well.

All in all steel shafts are the strongest, but the others can be as strong when made of a larger diameter than a steel ds of a smaller diameter.

Japanimal

http://www.acpt.com/article1.html

Looks like their are a few diff opinions out there as to which is better.

ceoart

I bet there are lots of people who would like to give you the Shaft

mooretorque

And you say you broke your shaft when you used it at high speed? Had to hurt.............