aluminum drive shaft - anyone?

[Dimman]

Originally Posted by Koa

"ever so slightly responsive and faster.. The true worth of this mod..."

Worth of expenditure and 'feel' are subjective.

Physics and the laws of motion are not.

Notice we're not saying the 15 pounds savings isn't worth ANYTHING. We're saying the cost per benefit is absurd for something that Rrealistically cannot be felt by those who are incapable of feeling the power increase that amounts to 44 milliseconds through a typical 0-100 run. That is an opinion. Definitely.

So there's that... you can indeed prove with mathematics what nature PROVES of this mod's worth. The real issue is that you come here saying you can actually feel a performance gain because unless you're a superhuman capable of feeling 44 milliseconds throughout a 0-100 run, you are just placebo tricking your mind. Probably NVH. There's that.

Come back with some "real world" track data to back up your claims and prove us, including physics, wrong. That you really won the race against yourself at the end of the day.

--

Here's the fatal blow to your position: A FUNDAMENTAL grounding principle of the scientific method: If the trial is not able to control all variables, which in this case would be driver error, it is no good. Show me a driver that is consistent to less than 100 milliseconds and I'll show you a liar. Prove me wrong in this.

THEREFORE,

With such a minuscule gain, this is an untestable claim that the driveline provides a perceived, "felt", benefit. Facts only become facts after artefacts and claims are subject to trials of strength, by various actors and laboratories and anti-laboratories. Only after the fact-to-be is able to be championed by those willing to test the claim, and survive the onslaught of trials of strength (testing), can the artefact become a FACT. Then, the fact can be altered and moved 'downstream' via positive modalities, or called out via negative modalities. Those are important themes to what's happening here. You're taking a fact that this type of reduction produces a gain, NO MATTER HOW MINISCULE, and moving that forward, via a positive modality, to "one is able to feel this gain throughout the driving experience- not just an increase of NVH, but an actual felt increase in power".

Bruno Latour, father of the discipline Science and Technology Studies, an increasingly important scientific discipline under the STEM cirricula, wrote at length about this in his landmark 1984 work, "Science in Action". I recommend you read this to understand the absurdity of your claims of real-world versus conceptual facts surrounding this case.

Conceptually, it's un-perceptible. It is supported by hundreds of years of scientific studies that humans' margins of errors in time tests exceed the milliseconds we're talking about here. Does that not ring a bell for you? Because that's a VERY important part of this discussion.

Can't argue with the scientific method.

Koa, I've shown that 44 milliseconds at 100 mph is a touch over 6 feet. Which is clearly noticeable.

I also redid Stu's formulas comparing stock vs a 15 lbs reduction of driveshaft (and total car) mass and came up with a difference of 99 milliseconds, which is over an entire car length at 100 mph. Very, very noticeable.

So far none of you have corrected any math failings on my part (which could very easily exist), so you look like you are taking Stu's numbers on pure faith and don't actually know what your talking about yourselves beyond math=good.

Alternatively my math is correct and it's too hard to argue that a car length difference on a 0-100 pull isn't noticeable.

[stugray]

Now we are arguing what the definition of "noticeable" actually is......

[CSG Mike]

I would 100% claim that a lightweight driveshaft is noticeable.

That's why CSG sells them.

[blackhawkdown]

I like Freschetta brick oven pizzas.

[Koa]

Originally Posted by industrial

We are going around in circles. The math that's parroted over and over again in this thread by stu is barely applicable. I disagree with your position and feel absolutely no need to prove anything to you or anyone else here. I know for a fact this mod is beneficial. That's enough for me. Whether or not I can feel it is another story. 5hp from run to run would not be discernible so does that make it not worthwhile? You have to understand your position is ridiculous. Just because you can't feel the benefit doesn't mean there isn't one or that it's not worth pursuing. Vote with your wallet and move on for fucks sake.

"parroting" math that is sound isn't negative. That's like telling a computer it is "parroting" the correct sequence to a given program. Just because it's being underscored doesn't diminish its value. Since you've stuck around so long, I am inclined to say you indeed feel the need to prove something to us... that you're justified in your purchase and that it has increased your performance, and conversely, happiness with your rig.

Happy to hear you're satisfied with your purchase. I would throw $400 at a well designed aluminum one piece if I felt it warranted the expense. For now, that $400 could buy me a track day and increase my times exponentially. I'm that novice of a tracker and not afraid to admit it. A race team is definitely going to want every millisecond and increased safety and will not bat an eye to spend that on an alu shaft. Glad we can agree on something <3

[Ultramaroon]

Originally Posted by Tcoat

Hey! How the hell did I get dragged into this!?
Like at work, I just enjoy sitting back and letting the engineers argue and then tell the winner he can't do what he wants anyway since the ROI is under 2 years!

Under, or over?

[Ultramaroon]

Originally Posted by CSG Mike

I would 100% claim that a lightweight driveshaft is noticeable.

That's why CSG sells them.

Fuck. Check and mate. You're the only guy who's butt dyno I believe.

[Koa]

Originally Posted by CBR600RR

Look, I I'll say it again, understand that the difference would be very minute, even to the point of being almost non-existent. I never claimed anything in the contrary. What I did say is that one is better than the other, which is 100% true and no one can argue that, but everyone seems to think I said that a light weight drive shaft is the miracle go-fast mod. Go back and read all my posts in this thread, and tell me I am wrong about anything. Please do.

Again, my point was simply that one is better than the other when considering an equal amount of weight.... Put it in the perspective of the racing community. Do they all ignore reducing rotational mass because its effects are minimal? No. In the racing world milliseconds count, and racing teams like to add all these milliseconds up so that they may have the best advantage.

I really hope that we can all just get along...

When I say it is "clear-cut-obvious" I am talking about the physics of it, not the butt dyno feel of the drive shaft. Take two completely stock cars, made the EXACT same, all conditions are the exact same, all variables are the exact same, the driver input is the exact same, but, reduce the over all weight of one car by 15lbs, and then put a driveshaft in the other car that is 15lbs lighter. Put them in a 1/4 mile drag race. The one with the light weight drive shaft wins every time. Even if you have to measure the win by nanometers, it still wins every time. Am I missing something here?

I want to underscore I'm not trying to prove you guys wrong or mad at ya'll over this. It definitely is an opinion that the benefit warrants/justifies the expense, with some clear lines drawn from all participants of the discussion. Can we applaud how far we've come, though, collectively?! We now know one more way to approach this discussion for future events. The OP probably learned a SHIT TON (evidenced by his "unsprung weight" and rotating mass mixup in the original post )

That's what it is all about. Pushing it forward. Sorry if I detracted any meaning from this discussion with unwarranted or crass responses or digs. Not the intent..

[EAGLE5]

Regarding critical speed...
Assuming top speed of 143mph in 4th gear...
Driveshaft RPM = (MPH)(1056)(Differential Ratio) / (Tire Diameter)(Pi)(gear ratio)

So...
Driveshaft RPM = (143MPH)(1056)(4.1) / (24.1)(3.14159)(1.213)

619132.8/91.839042947 = 6741.5rpm at 143mph in 4th gear, everything stock. That means, at most, a stock car needs a drive shaft that can handle a bit over 6741.5rpm.

So what is the critical speed of the AL drive shaft? I don't know how long the tubing is. ~6700rpm+ is my best guess for 52".If it's 50", more like ~7250rpm.

[stugray]

Originally Posted by CSG Mike

I would 100% claim that a lightweight driveshaft is noticeable.

That's why CSG sells them.

100% totally agree ... when standing under the car while on a lift :-)

Just out of curiosity: WHO has tested this with JUST the driveshaft upgrade? Most of the anecdotal evidence came from people who did multiple upgrades (some including the FW) all at once.

And I'll bet Mike can tell the difference between driving with all of the electrical accessories on vs off too! (not joking there, and not counting AC pump).

And I have absolutely zero problem with this upgrade - when done for the right reasons.
The lighter driveshaft: supports hp above stock, reduces NVH, is not susceptible to corrosion, probably safer in a rear-end collision, and WILL make some difference in performance.

However unless you intend to do all the other upgrades to reduce rotational inertia, there is very little ROI.

If you want to make reductions in rotational inertia, here are the places to make the change in order of "noticeable"effect:
1 - Tires (lighter, shaved, near end of life) also reduces unsprung weight
2 - Wheels (lighter) reduces unsprung weight
3 - Brake rotors reduces unsprung weight
4 - Flywheel, Pressure plate
5 - Pistons & Rods
6 - crank
7 - belt driven accessories
8 - pulley drive belt (edit - sorry meant cam drive/timing chains)
9 - Cams
10 - crank pulley
11 - driveshaft & axles
...
99 - Crank pulley bolt.

Disclaimer (you apparently NEED this on this forum): the above is My SWAG (scientific wild ass guess), but chances are that I am close.

So if you want to "feel" a difference on an otherwise stock vehicle, put the $400 towards some better wheels and have your tires shaved.

[stugray]

Originally Posted by industrial

The math that's parroted over and over again in this thread by stu is barely applicable..

Sorry, BUT the energy balance analysis (a VERY basic one) is the FIRST analysis performed on almost ANY mechanical system and is 100% applicable.
You can use better software and perform a more detailed analysis including friction and all those other variables, and you will STILL be somewhere in the 1/300 range for difference in stored energy of the system vs the driveshaft.
No way around that.

I KNEW this before I even did any calculations because it is OBVIOUS.
Consider it another way:
If I stood back and clocked someone over the head with a 30 lb driveshaft that had 3800 joules stored in it, that person would likely get up and kick my ass.
If I hit that same person with a 2800 lb car that had 1272176 joules stored in it,it would separate all their appendages, then fly through the person and knock down the building behind them.

Just a simple visualization of the problem is all that is required to "see the forest through all the trees".

[cdrazic93]

Stu idk why youre still wasting your energy.

[Koa]

Originally Posted by cdrazic93

Stu idk why youre still wasting your energy.

hey I'm still learning.. keep goin stu

[cdrazic93]

This thread is hilarious.

I dont care if anyone thinks this mod is noticable or not. My physics professor and textbook prove that the math behind the process of lighter weight materials used as a substitute for a driveshaft are most definitely below the threshold of human sensation.

I would be more invested in this argument, as i love a good debate (without name calling and harsh words and blatant, '@$!# you' comments lol). But i have studying to do.

I will keep track of this thread though. It provides me with some comical relief