aluminum drive shaft - anyone?

[Hawk77FT]

Originally Posted by D K

Would you rather lose 5lbs from your flywheel, or 5lbs from a lighter battery?

I think you are making a very valid point here! I would rather lose 5lbs of the flywheel and guarantee you 100% I will see and quantify the significant difference than losing 5lbs off the battery!

[Hawk77FT]

Originally Posted by stugray

Try this.

If a cyclist were to do the following two experiments, what would the results be:

Test A - Remove 10 grams from the perimeter of the tire and compare that to removing 10 grams from the seat.

Test B - Remove 10 grams from the wheel HUB and compare that to removing 10 grams from the seat.

What do you think?

The analogy applies this way for our cars:
Remove weight from the perimeter of the flywheel vs same weight removed from the spare tire: Noticeable difference! (removing from flywheel made a significant difference to rotational inertia)

Remove weight from the driveshaft (or the engine pulley) vs same weight removed from the spare tire: NO Noticeable difference!

Buddy, we are not talking here about 10gr, we are talking about half the weight of the stock.
Imagine this: a static bicycle with rear wheel that weighs 50 lbs and another one with 25 lbs. In 5 second from the standpoint, please tell me which one will reach a higher rpm applying the SAME amount of accelerating force to the pedals! The lighter wheel one will do it every time with no failure! Off the mark, the heavier one will need more force applied to reach the same high RPM as the lighter one. Pure physics! Try lifting a 40 or 80 pounds in 1 second and tell me which one you struggle more with?
Also, explain this: in the wet with the light weight driveshaft I can easily spin the tires, with stock ones, not so much! Same conditions, same tires/wheel combo, same rpm!
The benefits of a lighter driveshaft have been over discussed for quite some time now and YES, they do make a difference! No placebo, no make believe! Considerable difference as a matter a fact! Now, if you expect "turbo" difference then no, but couple this with some light weight wheels and you will have a smile on your face!

Nevertheless, this sounds like a really good deal! Plus it looks like it's got the sound deadening thing which will further reduce the resonance!

[Wayno]

It won't make lap times any faster, but you'll notice it in 1st and 2nd. At full price I wouldn't prioritize it over lighter wheels, tires, headers, tune, alignment, catch can, oil cooler, and probably some other stuff, but for 389 I'd grab one, or see what super special they have on carbon.

[s2d4]

Originally Posted by Hawk77FT

Buddy, we are not talking here about 10gr, we are talking about half the weight of the stock.
Imagine this: a static bicycle with rear wheel that weighs 50 lbs and another one with 25 lbs. In 5 second from the standpoint, please tell me which one will reach a higher rpm applying the SAME amount of accelerating force to the pedals! The lighter wheel one will do it every time with no failure! Off the mark, the heavier one will need more force applied to reach the same high RPM as the lighter one. Pure physics! Try lifting a 40 or 80 pounds in 1 second and tell me which one you struggle more with?
Also, explain this: in the wet with the light weight driveshaft I can easily spin the tires, with stock ones, not so much! Same conditions, same tires/wheel combo, same rpm!
The benefits of a lighter driveshaft have been over discussed for quite some time now and YES, they do make a difference! No placebo, no make believe! Considerable difference as a matter a fact! Now, if you expect "turbo" difference then no, but couple this with some light weight wheels and you will have a smile on your face!

Nevertheless, this sounds like a really good deal! Plus it looks like it's got the sound deadening thing which will further reduce the resonance!

He is not refuting that there are benefits.
Your example blows, the bike probably weighs 50lbs and the wheel weigh 10lbs.
We are talking 2800lbs for our cars, percentage matters.

[Sypher]

Originally Posted by Caspeed

Reducing rotational mass is generally a good thing. But remember that it's effect is determined by it's moment of inertia. The further from the center of rotation the greater the effect. 5Lbs from a wheel/tire assembly will be greater in it's effect (not even counting unsprung weight) than 5Lbs on a driveshaft.

100% correct. you will get a larger benefit from things with a the majority of its mass at a larger radius. In the discussion of what is the best way to remove rotational mass the wheels will always be #1 best place to shed weight.

one thing this thread seams to forget about is that the OP didn't ask where to loose rotational mass or what was the best way to loose unsprung weight (or sprung weight for that matter). He simply asked about aluminum drive shafts and if they are a good product.

Are lighter drive shafts the best way to loose rotational mass? No. Do they reduce rotational mass and sprung weight from the car? Yes.

While this example isn't exact it does cover the necessary points and some math.
http://www.thirdgen.org/forums/trans...riveshaft.html
this is a video of a mustang owner claiming to have compared his steel stock drive shaft to an aluminum aftermarket drive shaft.
[ame="https://www.youtube.com/watch?v=wvXYzUh8UYA"]2011 Mustang v6 Drive Shaft Testing and Dyno - YouTube[/ame]

[cdrazic93]

oh man, rotating mass, torque and inertia. Learned that in physics last quarter, you guys need to go back and look at that again haha.

[cdrazic93]

Originally Posted by industrial

after reading internet articles.

You don't need to read internet articles on this. Its rotational mass, this is something learned in an engineer's physics class, the hard science.

[cdrazic93]

Originally Posted by Hawk77FT

Pure physics! Try lifting a 40 or 80 pounds in 1 second and tell me which one you struggle more with?
do you even lift bro? lol
Also, explain this: in the wet with the light weight driveshaft I can easily spin the tires, with stock ones, not so much! Same conditions, same tires/wheel combo, same rpm! the coefficient for friction makes that example more complicated than just the variable of the driveshaft
The benefits of a lighter driveshaft have been over discussed for quite some time now and YES, they do make a difference! No placebo, no make believe! Considerable difference as a matter a fact! wheres your facts? links please, I'll take dyno's with a mod list from a well known tuner or a reputable company's statement they standby.

.

[industrial]

Originally Posted by D K

Would you rather lose 5lbs from your flywheel, or 5lbs from a lighter battery?

That's just it. I'd rather lose 30lbs from the battery, 45lbs from the spare/tools and 10 pounds from the driveshaft. These are false choices you guys are presenting. Anyone buying a driveshaft will most likely have done all the free and easy weight reduction already. If not, they should have.

[D K]

Unsprung rotational mass is the most important to try to lighten.
Then come unsprung mass and rotational mass ie flysheel, driveshaft pistons rods etc etc etc

Then comes sprung mass.

Every little bit counts!

I think it was Smokey Yunik who said unsrpung rotational mass was something like 20:1 compared to sprung mass and unsprung mass was 5:1 compared to sprung mass.

Its not really worth arguing.
Take the low hanging fruit first!
Flywheels and driveshafts are cheap and easy to do. Might not be much but still worth it

[stugray]

Originally Posted by Hawk77FT

Buddy, we are not talking here about 10gr, we are talking about half the weight of the stock.
Imagine this: a static bicycle with rear wheel that weighs 50 lbs and another one with 25 lbs. In 5 second from the standpoint, please tell me which one will reach a higher rpm applying the SAME amount of accelerating force to the pedals! The lighter wheel one will do it every time with no failure! Off the mark, the heavier one will need more force applied to reach the same high RPM as the lighter one. Pure physics! Try lifting a 40 or 80 pounds in 1 second and tell me which one you struggle more with?
Also, explain this: in the wet with the light weight driveshaft I can easily spin the tires, with stock ones, not so much! Same conditions, same tires/wheel combo, same rpm!
The benefits of a lighter driveshaft have been over discussed for quite some time now and YES, they do make a difference! No placebo, no make believe! Considerable difference as a matter a fact! Now, if you expect "turbo" difference then no, but couple this with some light weight wheels and you will have a smile on your face!

Nevertheless, this sounds like a really good deal! Plus it looks like it's got the sound deadening thing which will further reduce the resonance!

Just FAIL on so many levels.
"Also, explain this: in the wet with the light weight driveshaft I can easily spin the tires, with stock ones, not so much! Same conditions, same tires/wheel combo, same rpm!"

Absolute and utter bullshit.
You are starting with the driveshaft at ZERO RPM and when you "spin the tires" a difference of mass of the driveshaft of a few pounds makes almost ZERO difference to whether you can break the tires loose or not.
Because the rotational inertia change from the point where you havent broken loose to where you DID break loose is ZERO.
So there is ZERO energy stored in the driveshaft in that millisecond where the car is deciding if it has enough hp to break loose or not.
This problem is considered a STATIC physics problem while the rest of this discussion is about dynamics.

(do you also argue over economics with Ben Bernanke?)

[Koa]

Originally Posted by cdrazic93

Originally Posted by Hawk77FT View Post
Pure physics! Try lifting a 40 or 80 pounds in 1 second and tell me which one you struggle more with?
do you even lift bro? lol
Also, explain this: in the wet with the light weight driveshaft I can easily spin the tires, with stock ones, not so much! Same conditions, same tires/wheel combo, same rpm! the coefficient for friction makes that example more complicated than just the variable of the driveshaft
The benefits of a lighter driveshaft have been over discussed for quite some time now and YES, they do make a difference! No placebo, no make believe! Considerable difference as a matter a fact! wheres your facts? links please, I'll take dyno's with a mod list from a well known tuner or a reputable company's statement they standby.

Originally Posted by stugray

Just FAIL on so many levels.
"Also, explain this: in the wet with the light weight driveshaft I can easily spin the tires, with stock ones, not so much! Same conditions, same tires/wheel combo, same rpm!"

Absolute and utter bullshit.
.

CD, stu.. go easy on them! Rotational intertia change from standing stop.. coefficient of friction... fweight vs fnormal... brothers, they may not get it unless you dumb it down a little bit more. Hahah "in the wet"... get real

some real hard evidence people got logged here

[stugray]

Originally Posted by Sypher

http://www.thirdgen.org/forums/trans...riveshaft.html

Good link!
Here are a few quotes (anything sound familiar?):

"I am thoroughly happy there is another math man on here.

I do appreciate the effort. However as you know cars are a system of systems. Overall the mmi of the driveshaft is very small when compared with the rest of the drive train. Consider a 40lb crank with weights out at the ends. A 20-30lb flywheel/ torque converter with a huge radius. 30lbs of small radius components in the trans. A big heavy ring gear. Big heavy brake rotors and very big heavy wheels and tires. That is a lot of rotating weight. IMO the effect of the driveshaftis negligible. Both designs, steel and aluminum, are quite efficient compared to the rest of the system.

IMO the biggest advantage of the aluminum shaft is its corrosion resistance. "

AND

"Rotational energy = 1/2 m*rs^2*w^2
Translational energy = 1/2 m*v^2
m=mass; w=angular velocity; v=velocity of car; rs = radius of driveshaft ;

Let's say that the rear diff is 3.73 then the angular velocity of the ds is w=3.73*v/(8.67*rs)
The 8.67 is the ratio of the wheel radius over the driveshaft radius.
It turns out that the overall energy needed to rotate a driveshaft is about 1/10th that needed to move it forward. Then compare it with a 3000 lb car and it's a tiny fraction of the energy."

AMEN!

Look, I launch BIG rockets for a living. Does Physics say that IF I replace the 50 Steel bolts on the 1st stage adapter ring with titanium (for a difference of 1 pound), that physics says there will be a difference in the acceleration when the rocket leaves the pad? - YES!.
But HOW much difference when talking about a launch vehicle that weighs 1.1 MILLION pounds at liftoff? IN THE NOISE

[cdrazic93]

Damn it stu, @Koa just said go easy *facepalm*