aluminum drive shaft - anyone?

[s2d4]

Use science to save noobs money = wanker.
Got it, people argue about stuff, gets proven wrong then say what an ass for proving them wrong.. Just can't win.

[cdrazic93]

[cdrazic93]

Originally Posted by Dimman

Real asshole, maybe.

What facts? That Jimmy won't see as much a benefit from it as he thinks? Same as the NA vs Turbo argument. Not his business to bitch about how someone wants to spend mod money.

The 'where to spend your money' is a personal opinion, yes. What upset him was that he refuted everyone's examples with math (pretty factual stuff dontcha know ) that a lighter weight drive shaft doesnt net any noticeable difference. He repeated himself probably about 15 times with multiple examples.

Yet everyone swore that it made a huge noticable performance gain.

It doesn't.

[industrial]

Originally Posted by cdrazic93

The 'where to spend your money' is a personal opinion, yes. What upset him was that he refuted everyone's examples with math (pretty factual stuff dontcha know ) that a lighter weight drive shaft doesnt net any noticeable difference. He repeated himself probably about 15 times with multiple examples.

Yet everyone swore that it made a huge noticable performance gain.

It doesn't.

How do you prove with hard science that something does not produce an effect that is noticeable? It's pure speculation on how someone may perceive the difference based on "internet science". I don't care if someone claims to be an engineer here, you can say anything you want. The way he acts strikes me as more of a typical reddit kid that can look stuff up rather than someone who actually works in science or knows anything about the most basic tenants of science. I mean, if the absolutely ridiculous analogies he comes up isn't a glaring example to his real level of knowledge I don't know what is.

There really is no real way to dumb down the physics here. It's complex. It should be enough to know that losing 10 pounds for $400 might be worth it as is. The fact that it's also rotational weight absolutely makes a positive impact. How can we quantify this? It's hard. It's hard to quantify how exactly a lot of things work but we can explain it qualitatively. Why does one person get to force his theoretical qualitative opinion down everyone's throat? That's fucking ridiculous. Go tell people that black taillight housings suck because your opinion as someone who doesn't own a black taillight is parroted by other car forum sheeple. This is a car hobby. None of it really makes sense. This is for fun.

Someone in this thread is basically saying...based on articles he's read, he doesn't think we should feel what we are feeling. People can physically taste the difference between 2 identical liquids based on the label on the outside. We are that susceptible to our brain overriding our senses. If installing a driveshaft really does make someone feel their car is faster, who the fuck are you to say otherwise?

[Sypher]

Originally Posted by Koa

He said noticeable difference bro. That, combined with the findings that the ratio for rotational to nonrotational mass is 1.1:1 (I.E no realizable difference when we're looking at 10 pounds, which would mean that 10 pounds taken from the driveshaft equals 11 pounds taken anywhere else)

Sorry bud but you can't argue with physics. Love that you ignore everything in the forum and focus on what you can wrap your mind around

Actually if you fill out the calculator provided by this site http://www.hpwizard.com/rotational-inertia.html#answers that i reference before you get a ratio of 1.26:1 (this is assuming the stock drive shaft is 3" dia. and using 1/8" thick wall as i can't seem to find the stock drive shaft dims)

[Turdinator]

I suspect the "noticeable difference" comes from more than just weight reduction. My guess is the lack of centre bearing and other things to control NVH built into the stock drive shaft make for a more direct feeling of power delivery.

I believe @stugray that the weight reduction will have a negligible effect on the car but @Dimman has a good point, it is not up to Stu how people spend their money and he should know that arguing with people on the internet is a waste of his intellect. Make your case and move on whether people believe it or not. The right people will read it and learn from it. This is a forum, I could start a thread about the sky being blue and someone somewhere would argue with me.

[stugray]

Originally Posted by industrial

I don't care if someone claims to be an engineer here, you can say anything you want. The way he acts strikes me as more of a typical reddit kid that can look stuff up rather than someone who actually works in science or knows anything about the most basic tenants of science.

Originally Posted by CBR600RR

I think you need to go back to school and learn some general laws of physics.

Things that Stu has actually touched with his hands have/are:
Landed on Saturn's moon, orbited Mars, orbiting Saturn, returned sample from a comet, returned a sample from the sun, landed on Mars (twice), punched a hole in a comet, Orbiting sun discovered 1000s of planets, 4X orbiting Earth now.

So I believe that I am: a little older than a typical reddit kid, have a clue about "that physics shit", and know my way around mechanical modeling of complex systems. (one of my last jobs was to spend a million dollars modelling how a spring loaded mirror bounces off a hardstop in zero G).
I am personally responsible for dynamics testing on BILLION dollar spacecraft.

But I guess my kind isnt wanted here so I'll just fuck off then.

[Dimman]

Originally Posted by cdrazic93

The 'where to spend your money' is a personal opinion, yes. What upset him was that he refuted everyone's examples with math (pretty factual stuff dontcha know ) that a lighter weight drive shaft doesnt net any noticeable difference. He repeated himself probably about 15 times with multiple examples.

Yet everyone swore that it made a huge noticable performance gain.

It doesn't.

He's free to take his scientifically correct attitude to an NA thread and show them they're all idiots for wasting their money by not going FI. I'm sure he's a big hit at parties.

[cdrazic93]

Originally Posted by industrial

How do you prove with hard science that something does not produce an effect that is noticeable? It's pure speculation on how someone may perceive the difference based on "internet science"[1]. I don't care if someone claims to be an engineer here, you can say anything you want. The way he acts strikes me as more of a typical reddit kid that can look stuff up rather than someone who actually works in science or knows anything about the most basic tenants of science[2].

The fact that it's also rotational weight absolutely makes a positive impact.[3] How can we quantify this? It's hard. It's hard to quantify how exactly a lot of things work but we can explain it qualitatively. Why does one person get to force his theoretical qualitative opinion[4]
Someone in this thread is basically saying...based on articles he's read, he doesn't think we should feel what we are feeling.[5]

1. This is straight from my textbook; "the quantity in rotational dynamics that takes into account both magnitude of the force and the direction and location at which it is applied is called the torque"(pg.175)welcome to rotational dynamics.

For a given torque, we get a different angular acceleration when mass is close to the axis of rotation than we get when it is farther away." This means that the drive shaft, that is a tube, has the mass at x distance away from the axis of rotation. The rotational quantity that describes the mass of the body and its distribution relative to the axis of rotation is called rotational inertia. (1)

2. The way he acts? He gets frustrated (and rightly so) that many people refuse to acknowledge math.

3. Actually if we're getting all technical on this; its rotational mass; not weight.

Rotational Acceleration=∑τ = I α
Torque is explained as t = r cross F
rotational inertia is I=integral from [a,b] of r^2 dm
work is described as w=dW/dtheta
angular momentum is described as L=integral from [a,b] of dVr cross p(r)v


now that we have that out of the way, the formula (from my textbook) of a rotating cylinder about an axis is I=(1/2)M(R^2+r^2). Where M is the mass. Mass is directly proportional to Inertia. "Unlike the mass, the rotational inertia of a body is not an intrinsic property of the body, but instead depends on the choice of axis of rotation. Just as the mass can be regarded as the property of a body that represents its resistance to linear acceleration, the rotational inertia represents the resistance of a body to angular acceleration." (pg. 175-176)

4. It's not theoretical opinion, when its math.

5. not based on "articles" he has read. It's based on math.

Academia is about as far from "internet science" as you can get.

work cited: Resnick, Robert, and David Halliday. "Rotational Dynamics." Physics. 5th ed. Vol. 1. New York: Wiley, 1992. 175, 176. Print.

[continuecrushing]

[industrial]

Originally Posted by cdrazic93

1. This is straight from my textbook; "the quantity in rotational dynamics that takes into account both magnitude of the force and the direction and location at which it is applied is called the torque"(pg.175)welcome to rotational dynamics.

For a given torque, we get a different angular acceleration when mass is close to the axis of rotation than we get when it is farther away." This means that the drive shaft, that is a tube, has the mass at x distance away from the axis of rotation. The rotational quantity that describes the mass of the body and its distribution relative to the axis of rotation is called rotational inertia. (1)

2. The way he acts? He gets frustrated (and rightly so) that many people refuse to acknowledge math.

3. Actually if we're getting all technical on this; its rotational mass; not weight.

Rotational Acceleration=∑τ = I α
Torque is explained as t = r cross F
rotational inertia is I=integral from [a,b] of r^2 dm
work is described as w=dW/dtheta
angular momentum is described as L=integral from [a,b] of dVr cross p(r)v


now that we have that out of the way, the formula (from my textbook) of a rotating cylinder about an axis is I=(1/2)M(R^2+r^2). Where M is the mass. Mass is directly proportional to Inertia. "Unlike the mass, the rotational inertia of a body is not an intrinsic property of the body, but instead depends on the choice of axis of rotation. Just as the mass can be regarded as the property of a body that represents its resistance to linear acceleration, the rotational inertia represents the resistance of a body to angular acceleration." (pg. 175-176)

4. It's not theoretical opinion, when its math.

5. not based on "articles" he has read. It's based on math.

Academia is about as far from "internet science" as you can get.

work cited: Resnick, Robert, and David Halliday. "Rotational Dynamics." Physics. 5th ed. Vol. 1. New York: Wiley, 1992. 175, 176. Print.

Yeah, schooled me. Too bad I have no idea what point you're actually trying to make. To be brief, you and me and stu all agree on the math and science. Is been this way since the beginning of the thread. Where our differences lie is in the statement by stu that the loss of said rotating mass can not be felt in a significant way. This is the hypothesis that I am rejecting:

The difference in mass between a stock and aluminum driveshaft is imperceptible.

That may even be true in a scientific study but in the real world with no controls, just knowing you installed such a component can cause you to feel a difference in your brain. The buttdyno effect. In this case however, all the math supports that losing mass on the driveshaft is beneficial anyway so...what are we really arguing here? Whether someone thinks it's worth it? People pay big money for stanced cars in this community. I think you guys are barking up the wrong tree. Perhaps you guys should go fight a battle worth fighting like HID retrofits on lifted 1990s trucks?

[cdrazic93]

Originally Posted by industrial

Yeah, schooled me. Too bad I have no idea what point you're actually trying to make.

my point is in blue.

[cdrazic93]

Originally Posted by industrial

so...what are we really arguing here? Whether someone thinks it's worth it? People pay big money for stanced cars in this community.

If the argument is based on $/mod then that's opinion based. I am proving the math behind the facts.

[SurfAndSand]

I love the Internet. Everyone tries to "win" a discussion thread.