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Whats the advantage or disadvantages, any ET reduction?
 

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I have one in my Firebird. The car lost 8 lbs. over the steel shaft. And my wallet lost some weight also. I didn't run the car with the steel shaft ( to short ) So I can't give you performance gain figures. There may be some but I think it would very small. I went that route because I had to replace the shaft. If my steel shaft was the right length I wouldn't have done it. If you looking for performance gains the 1K is better spent else where.
 

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There are several post with good information in them in here already, search for it. Should help ya out a little.
 

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See the differential section, i have answered this question in there.

Simply put though, losing lbs in the driveline is like losing a few hundred lbs carrying... so if you lose 10 lbs it's like taking 250 to 300 lbs out of the seat.
I have had many cars lose .07 to a full .10 losing weight in the shaft, whether it was lightening stl shafts or losing the stl and going to AL or CF
 

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See the differential section, i have answered this question in there.

Simply put though, losing lbs in the driveline is like losing a few hundred lbs carrying... so if you lose 10 lbs it's like taking 250 to 300 lbs out of the seat.
I have had many cars lose .07 to a full .10 losing weight in the shaft, whether it was lightening stl shafts or losing the stl and going to AL or CF
Sorry but I don't agree. Its all dependant on moments of inertia. The gains will be in the "time" you allow a part to accelerate , not just the weight and saying its "rotating".

I took 15 lbs from my crankshaft and my car doesn't act 1500 lbs lighter but my block stopped whining.

By gun drilling axles it helps with static weight but does sweet dick for ET because the diameter is too small.



Hutch
 

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I have hundreds of customers that have seen differently, including my own testing, years ago when we 1st started playing with shafts, before AL, we lightened the stl shafts, to dangerous weights, that made a world of difference.
I have 2 identical SS cars, 1 shaft is lightened, 1 shaft is not. Guess which car always wins...the only difference between them..... paint color and the driveshafts weight
AL came along, and i put AL in everything, my DD, shop vehicle, trucks, EVERYTHING
Everyone of them changed, tires could be spun, mileage went up, passing was immediately noticed

It takes less time to turn 10 lbs than it does 28 lbs, and so a car that is always consistent will see an improvement.

I have seen gains in mileage, time and distance.

Diameter has nothing to do with weight...

I can take a 1" diameter shaft that weighs 100 lbs and put it in my machine and time how long it takes to get to speed.
I can then take another 1" lightened shaft and do the same thing.....

Time after time after time, it's always the same, lighter is faster...

15 lbs off your crank you should have seen a very good difference

In my world the shaft and diff aren't at speed, they are ___ lbs that need to be moved, they need to be accelerated from a stop, and EVERY single one has gone faster when they have been lightened, those that are already in motion (road racing), have felt the improvement in accel and seen mileage improvements.

If you were right, then ALL cars no matter there weight will all go the same speed with 1000hp...
 

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Im not here to argue with you and I won't but Im allowed to disagree. I too am in a world where weight and rotating mass is everything so don't think its my first day on this topic and I won't assume its yours. Yes lighter weight driveshafts will always be a better way to go but some of your rules of thumb may not apply to all cases is my point which can't be disputed.

Now to your argument about spinning a shaft and the power it consumes VS diameter. Diameter is EVERYTHING.

If I give you a shaft that is 100 lbs and 1" round and I ask you to get it to 1000 rpm in 5 seconds. How much power will that consume? (look at this as a car with a 2.76 rear ratio)

Now I give you the same shaft again and I ask you to do the same thing in 2 seconds. How much power will that consume? (look at this as a car with a 5.57 gear)

Shaft #2 will take much more power to accelerate it so it will give back more benefit to being lighter than shaft #1.

Now take those 2 examples and make the part exactly the same weight do the same tests and make it 5" around, the power consumption may go up by 4 times. Diameter is the killer not necessarily the weight.


Hutch
 

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Actually that's not right... Ok example.... a stl shaft in 3" at 20lbs, vs a 4" AL shaft at 11lbs....

That car lost .09

If i build a 3x95 shaft and a 3.5"x65 shaft at the same length, the 3.5" shaft will be the faster car

Same as if you put together a AL drumed/hub lightened trans together, vs a heavy trans.

Diameter in the trans world you may see differences, since in your world you may not be able to control the larger diameter being heavy.
Say a 6" clutch vs a 8" same material, then you're right.

I can control diameter and weight

I just did a 5" shaft that was faster than the 3.5" shaft in a customers truck.... 3.5 was stl, the 5" was Al... same length...

Weight is weight, the motor doesn't know it's turning a 5" 20 lbs shaft vs a 3" 20 lb shaft...
Doesn't matter..

My jeep uses a 3" shaft, it went from a 2.5" shaft, the 3" shaft is faster, because it is lighter than the 2.5" shaft
 

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Actually Hutch is right. Rotational inertia goes up as the square of the diameter. In other words: take two shafts of the same weight - one is 2" OD and the other 4" OD. The one twice as big takes 4 times the energy to accelerate. It is a fact.
The only thing you can change is how the weight is distrubuted within the part but since we're dealing with hollow shafts it's apples to apples.
 

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Back to carbon fiber as a material. You have to be very careful with it and not let the shaft hit the driveshaft loop etc. when removing it. It is easier to damage than a metal shaft, I have heard.
 

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Fight Fight Fight,

This is what i wanted to see, not butting of heads but "data" from one to another on which is best. I know a carbon fiber is lighter and safer but thats not what im after.... Im looking for "gains" if any
 

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Actually Hutch is right. Rotational inertia goes up as the square of the diameter. In other words: take two shafts of the same weight - one is 2" OD and the other 4" OD. The one twice as big takes 4 times the energy to accelerate. It is a fact.
The only thing you can change is how the weight is distrubuted within the part but since we're dealing with hollow shafts it's apples to apples.
I just told you that isn't true, and i just gave you 2 examples....

Ok let me give more....

My jeep, gained, from 2.5" to 3"
My truck gained from 2.5" to 3"
customer from 3.5" to 4" went .09 faster
customer 3.5" to 5" shaft, truck is faster and p/u 1.8 mpg...
You can not p/u mpg and use more hp to turn something.

Customer went from 3" CM to 3.75 CF went .07 faster

So far the theory of increasing diameter is wrong...

I can test diameter theory all day as i see it all day anyway, i do it all the time.

AS the diameter increases the amount of torque or power by area is increased.
AS weight is decreased the amount of time to get said piece to speed is quicker...

I see that all day everyday.....

Back to carbon fiber as a material. You have to be very careful with it and not let the shaft hit the driveshaft loop etc. when removing it. It is easier to damage than a metal shaft, I have heard.
As for damaging it.... pulling it out and it falls the 1.5" to the loop as it comes of the trans and you pull it out sliding it along the loop won't hurt it...

Hitting it against something making a dimple or loosening the fiber can cause a issue.

Scaring it because the loop is to tight can effect it's strength

CF and AL are very close in weight, CF is more rigid than AL and stl, CF has a gain in torsional ability also over Al and stl
 

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Fight Fight Fight,

This is what i wanted to see, not butting of heads but "data" from one to another on which is best. I know a carbon fiber is lighter and safer but thats not what im after.... Im looking for "gains" if any
If you do not have a consistent car you may never see a gain, you can feel it, if you are used to the car though.
 

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I just told you that isn't true, and i just gave you 2 examples....

Ok let me give more....

My jeep, gained, from 2.5" to 3"
My truck gained from 2.5" to 3"
customer from 3.5" to 4" went .09 faster
customer 3.5" to 5" shaft, truck is faster and p/u 1.8 mpg...
You can not p/u mpg and use more hp to turn something.

Customer went from 3" CM to 3.75 CF went .07 faster

So far the theory of increasing diameter is wrong...

I can test diameter theory all day as i see it all day anyway, i do it all the time.

AS the diameter increases the amount of torque or power by area is increased.
AS weight is decreased the amount of time to get said piece to speed is quicker...

I see that all day everyday.....



As for damaging it.... pulling it out and it falls the 1.5" to the loop as it comes of the trans and you pull it out sliding it along the loop won't hurt it...

Hitting it against something making a dimple or loosening the fiber can cause a issue.

Scaring it because the loop is to tight can effect it's strength

CF and AL are very close in weight, CF is more rigid than AL and stl, CF has a gain in torsional ability also over Al and stl
You are telling the engineering world they have no idea about rotational inertia. You are factually wrong! No arguing about it! Take a 40lb dumbbell in your hand and rotate it as fast as you can, now take a 30lb bar that is 6 feet long and rotate it as fast as you can, much less stop it! It will take you much, much longer to rotate the bar 6 foot bar that is 10lbs lighter.

This is why a 3.5" Carbon Fiber shaft is going in our car and not a 4" Aluminum. CF is lighter and smaller in diameter.

Your argument is really about the diameter and weight reduction of a rotating mass. Like everything in the world, there is always a compromise.
 

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No i do not want to buy a trans shop, thank you

If you were to stand next to me and watch it happen, would you believe it then...

I can find more examples....
I can find more examples of people who gained mpg and do not race, another form of using less energy...and exerting less force...
 

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You are telling the engineering world they have no idea about rotational inertia. You are factually wrong! No arguing about it! Take a 40lb dumbbell in your hand and rotate it as fast as you can, now take a 30lb bar that is 6 feet long and rotate it as fast as you can, much less stop it! It will take you much, much longer to rotate the bar 6 foot bar that is 10lbs lighter.

This is why a 3.5" Carbon Fiber shaft is going in our car and not a 4" Aluminum. CF is lighter and smaller in diameter.

Your argument is really about the diameter and weight reduction of a rotating mass. Like everything in the world, there is always a compromise.


4" AL is heavier then 3.75 CF...

Did you not read the part where i said,

I did a stl 3.5" shaft to 5" AL shaft...

the 3.5" shaft was stl, the 5" shaft was AL..

the 5" shaft was faster to accel and faster to stop...it increased mpg and accel...

I do not care what diameter you find, if the larger diameter is less weight you are wrong

Let me try this

If you want to stand next to me and i take a 3" stl shaft and a 4" AL shaft and when im right, you buy both of them for 3x the price...

Sounds fair for me to waste my time right ?
DIAMETER is a area of strength

Weight is negative, that takes power to drive it..

A lot of you are confusing things.

Again if you want, come to the shop you watch the entire process and time the shafts to speed and stop, and you can stop them with your hand...

I'll bet you an additional 2k, you break your wrist stopping the smaller steel shaft...

Trust me, i never bet on something i do not or haven't made sure of it is correct...
 
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