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Old 03-10-2012, 10:30 AM   #1
Bad00SS
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Default Any gains switching to aluminum driveshaft?

What kind of gains will you see goin from chromoly to aluminum driveshaft? PST says I can use 3.5" aluminum as long as your under 1,000hp. Currently have 3" chromoly. Car makes 600hp 3,460 race weight. Is it worth the money?
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Old 03-10-2012, 12:58 PM   #2
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Default Re: Any gains switching to aluminum driveshaft?

You should see 7 hundredths to 1 tenth at the track, on the street you can gain some mpg.

Make sure you aren't getting china with that pst shaft, can't rate a shaft at 1000hp and use a iffy 300-hp china slip yoke.
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Old 03-10-2012, 05:03 PM   #3
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Default Re: Any gains switching to aluminum driveshaft?

A tenth????? thats usually 100LBS on the scale?? Explain this please unless the driveshaft is taking of 100lbs of weight.
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Old 03-10-2012, 06:13 PM   #4
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Default Re: Any gains switching to aluminum driveshaft?

rotating weight makes a big differnce. wheels, axles, driveshafts, light transmission parts all make more of a differnce than the actual weight they weigh if removed from a car. i think it all ties in with drivetrain HP loss sort of. it takes less power to spin a light driveshaft than a heavy one. so there for more power gets put to the ground. someone correct me if i'm wrong.
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Old 03-10-2012, 09:01 PM   #5
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Default Re: Any gains switching to aluminum driveshaft?

It doesn't help as much as we believed from the manufactures of the products. The read below is a good one and makes sense of it. Unless your runing a fast accelerating sub 5 sec 1/8 miler or deep into the 8s in the 1/4, most of the light weight rotating ideas have little effect.

http://www.w8ji.com/rotating_mass_acceleration.htm

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Old 03-10-2012, 09:35 PM   #6
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Default Re: Any gains switching to aluminum driveshaft?

thanks, good read.
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Old 03-11-2012, 01:47 PM   #7
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Default Re: Any gains switching to aluminum driveshaft?

Quote:
Originally Posted by Comax Racing View Post
A tenth????? thats usually 100LBS on the scale?? Explain this please unless the driveshaft is taking of 100lbs of weight.

Actually the difference in weight of AL and Stl shafts is equal to removing more than 200 lbs of carrying weight.

A pounds in the driveline are equal to tens of pounds of carrying.
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Old 03-11-2012, 02:00 PM   #8
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Default Re: Any gains switching to aluminum driveshaft?

Quote:
Originally Posted by windedv6 View Post
It doesn't help as much as we believed from the manufactures of the products. The read below is a good one and makes sense of it. Unless your runing a fast accelerating sub 5 sec 1/8 miler or deep into the 8s in the 1/4, most of the light weight rotating ideas have little effect.

http://www.w8ji.com/rotating_mass_acceleration.htm

John

That is more of an example for FLYWHEELS where the weight is further out...

Example i have several off-shore race boats i do, imagine if that article was right , how did a 3.5" slt shaft which is heavier than a 4.5" al shaft allow the motors to see 200 more top rpm ?
The boats were also quicker to plane and infact both needed to redo props at a very large expense do to the characteristics of the lighter AL shafts.
Another boat has a direct coupled motor and a staggered, the staggered was using a 3.5" stl shaft and went to a 4" AL shaft i had promised he'd see a improvement in and get back the power he is missing on that motor, he did that motor got the lost 175 rpm it was missing.
Trucks have gained as much as 2 mpg from AL shafts, DD cars also have gained a 1mpg improvement and easier acceleration.

When you want to compare 5" to 2" diameters to that of 10" and larger flywheels and stored energy theories things are completely different , until we go beyond a certain diameter it has no effect like flywheels do, that is a different world VERY much confused.

If lighter shafts do not make a difference then all the things i have seen happen aren't real, the SS cars that some have picked up 5 hundredths over others simply because i spent time lightening there stl shafts must be from some strange phenomenon other than the lightening of certain areas of there shafts.

Every pound you lose that must be turned to accelerate is a gain

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Old 03-11-2012, 03:02 PM   #9
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Default Re: Any gains switching to aluminum driveshaft?

Quote:
Originally Posted by Supershafts View Post
That is more of an example for FLYWHEELS where the weight is further out...

Example i have several off-shore race boats i do, imagine if that article was right , how did a 3.5" slt shaft which is heavier than a 4.5" al shaft allow the motors to see 200 more top rpm ?
The boats were also quicker to plane and infact both needed to redo props at a very large expense do to the characteristics of the lighter AL shafts.
Another boat has a direct coupled motor and a staggered, the staggered was using a 3.5" stl shaft and went to a 4" AL shaft i had promised he'd see a improvement in and get back the power he is missing on that motor, he did that motor got the lost 175 rpm it was missing.
Trucks have gained as much as 2 mpg from AL shafts, DD cars also have gained a 1mpg improvement and easier acceleration.

When you want to compare 5" to 2" diameters to that of 10" and larger flywheels and stored energy theories things are completely different , until we go beyond a certain diameter it has no effect like flywheels do, that is a different world VERY much confused.

If lighter shafts do not make a difference then all the things i have seen happen aren't real, the SS cars that some have picked up 5 hundredths over others simply because i spent time lightening there stl shafts must be from some strange phenomenon other than the lightening of certain areas of there shafts.

Every pound you lose that must be turned to accelerate is a gain

.
Never stated that the wasn't applications for lighter driveshafts, just not most street/strip setups.

Here is the writers explanation on driveshafts....

"Drive Shaft Example
Now let's think about a drive shaft. The driveshaft is a fairly thin hollow tube. Nearly all drive shaft weight is at the outside, since it is of course hollow. The shaft also turns at the same RPM no matter what the driveshaft diameter, because the RPM is set by the rear end ratio, tire diameter, and vehicle speed. If we make a driveshaft lighter and keep everything else the same, the vehicle acceleration change is most often insignificant.
Why insignificant in most cases?
In the first place, the drive shaft is small in diameter. With a small diameter, less energy is stored for a given weight. In the second place, a driveshaft is really not that heavy. A steel Mustang driveshaft weighs somewhere around 30 pounds, so we just can't take that much weight out.
Also, the driveshaft spins up gradually and smoothly over a long period of time. It accelerates fastest at slowest speeds, and that is when it needs the least energy to spin up. Because it has a long time to spin up, is a small diameter, and doesn't weigh much the driveshaft does not remove very much horsepower at any instant of time. Despite what we are told, a change in driveshaft weight has at best a very small effect on acceleration. Likely any change is immeasurable in a street/strip car.
Now a lighter shaft certainly can help in a very light vehicle or in a road race car where instant change in applied power is required, but it really won't change much in a 3000-pound 11-second car, except how fast dollars leave your wallet!"



I would imagine that a boat direct shaft can get to full acceleration extremely quickly, thus a lighter shaft to spin would be benefical. A track car driveshaft doesn't reach its max speed until its at the end of the track and is barely turning at 60' out. Axles shafts are turning even slower. This is a big rotating mass difference to a flywheel and certain trany parts that are running at max rotations right out of the gate.

Street/strip cars runing 90-100 mph in the 1/8 or 115-125 in the 1/4 probably aren't going to show much improvement in the rotating weight saving of an AL drive shaft. Start spinning them in the 150-200 mph range and getting them in the 100 mph plus range shortly out of the gate, then there should be usable rotational weight saving.
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Old 03-11-2012, 03:38 PM   #10
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Default Re: Any gains switching to aluminum driveshaft?

If you think a 12 second car would have no GAIN or the effect of in reality losing as much as 300 lbs of effectively carrying weight you are buying this writers bs. . .
OK forget the boats lets concentrate on the cars since you MISSED how DIAMETER has no effect on that end of the driveline which is why i used the boats as an EXAMPLE to this off theory of the 3.5" heavier shaft was slowing the boat with a lighter 4.5" and 4" AL shaft. . . .
I have quite a few SS cars with just a few lbs in difference than other exact cars and which they are faster than there non lightened competition, and since they can not use AL i have to do other things to make them light, of which i can almost get them down to the weight of AL, everyone of them all improved.
Street cars that if you floored it you were lucky they moved, suddenly they have wheel spin, and accelerate to 60 faster (like a 19 second pos DD), and gets better mpg. . . so removing 10 lbs and 20 lbs from the driveline does prove the writer wrong because he is talking diameters and never did any REAL tests or he surely wouldn't have said that. . .

You're also comparing the shaft to the wheel just like the WRITER is, why does my machine accelerate the lighter shafts faster? why does my car accel easier, why is my DD suddenly have more power at the wheels, why does my truck accel faster and get better mpg and i no longer have to use half throttle to make a pass, IM No longer TRYING to TURN 35 lbs or 50 lbs or 75 lbs.

If you have 50 lbs to turn you really think this writer has a clue when you remove that 50 lbs and replace it with 12 lbs, do you really think he has any idea, he is making the same stupid mistake of outside DIAMETER of a moving wheel, this is the same mistake EVERYONE makes, i had this same issue with a trans guy, just could not understand FORGET the DIAMETER, forget everything you know about rotating mass and transmissions IT DOES NOT APPLY to standing weight we are dealing with STANDING WEIGHT........................................


If this guy is right go put heavy cheap stl wheels on your car, fill them with water too, it makes no effect, do you now see how stupid that writer is. . . .



DIAMETER has no effect here, it's standing WEIGHT YOU MUST GET TURNING. . .

Does the writer also realize that this is why manufactures are using AL and CF in there drivelines now, because they see the benefits to performance and MPG

As for his theory on lightweight wheels, i have a lightweight wheel in my truck, it tows anywhere from 8500 lbs to 21,000 lbs his theory on that seems to also be off, i may have to slip the clutch a 10th of second more before i side step it, but everyother gear after that that truck pulls nasty, twisting the frame leaving the light, twisting the frame crashing 2nd and 3rd, gets to 2nd and 3rd faster too. . . .so the lighter vs needing heavier doesn't apply there either as per his theory
A heavier flywheel masks more harmonics better, but thats all i see as for the difference in wieghts.
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Old 03-11-2012, 03:46 PM   #11
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Default Re: Any gains switching to aluminum driveshaft?

That guy contradicts himself, read the rest see what he says at the end, how is it you're hitting the tires harder, you're freeing up lost hp being absorbed by weight
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Old 03-11-2012, 04:15 PM   #12
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Default Re: Any gains switching to aluminum driveshaft?

I have put aluminum driveshafts on every single 5.0 fox I have ever built. At the track it was worth .2 in the 60ft, give or take a few thousandths, It was worth 1-2 tenths in the 1/4 and anywhere from 1-4mph, depending on the rest of the combo.
These were back to back tests.
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Old 03-11-2012, 04:51 PM   #13
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Default Re: Any gains switching to aluminum driveshaft?

2 tenths to me would be worth the 600 bux. That's decent gain
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Old 03-11-2012, 05:18 PM   #14
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Default Re: Any gains switching to aluminum driveshaft?

how much HP can an Aluminum Drivshaft take in a 3000 lb. car? 1000? 1500? 2000? any ideas?
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Old 03-11-2012, 05:18 PM   #15
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Default Re: Any gains switching to aluminum driveshaft?

I have tested shafts on everything my cars, my trucks the tow vehicle including the shop truck, and even the shop truck is faster and better mpg.

Years back before the factories started using AL in trucks we knew that tailshafts in helos (for the tail rotor) were long and a single shaft and that the reason for that was AL can run longer distances and not break because it was lighter, so to save MONEY when a customer would come in with a 2pc shaft i made a single pc AL shaft for my truck, the acceleration was the 1st thing i noticed the mpg took months to notice because the truck felt as if it was making 100 more hp and i was racing it all over
So somewhere in the 90's we began giving customers the option, we can redo the stub/slip/hanger and joint for X amount, or i can for the same money do this in 1 AL shaft at this diameter and also make you feel like you gained 75 hp.
Every single customer that listened and didn't listen to stupidity about AL being weaker from some WRITER and this and that gained mpg and thought we did something to their truck to make it have the easier throttle response it had and quicker accel.


I have never seen a car/truck/boat lose weight in the shaft and not benefit atleast in 1 area if not 3.
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