does anyone know the weight diff? or any gains"rotating mass" or is it just for vibration?
how much weight difference is there between stock driveshaft and aluminum one?
rsw007
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It is actually 8.5 lbs lighter than stock.zeus said:
They actually help free up drivetrain horsepower that is normally lost while driving.
If you normally lose 15% horsepower in a 5 speed drivetrain, they help reduce that by a few percentage (e.g to 12%,13% or 14%)..and the most gains should be felt with an AUTO.
They have been known to help with gas mileage too.
I sell them all the time.
Ken
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They hardly weigh any different than stock. I had the stock one in one hand and the aluminum one in the other and they felt identical to me. 3-4 lbs I believe. 8.5 I have a hard time believing.
Anyway they're larger than stock so the rotational inertia is the same.
Therefore:
They do NOT make the car faster.
They do NOT help with fuel mileage.
They DO change the vibrational characteristics of the drivetrain making it much less likely to vibrate at highway speeds with non-stock gears.
Anyway they're larger than stock so the rotational inertia is the same.
Therefore:
They do NOT make the car faster.
They do NOT help with fuel mileage.
They DO change the vibrational characteristics of the drivetrain making it much less likely to vibrate at highway speeds with non-stock gears.
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Unless they specifically designed it to, it has to change the rotational inertia. I am willing to bet money that they did not engineer the thing to have the same rotational inertia as stock. I also just changed mine, and though I didnt weigh it, it was a substantial weight difference when handling it. 8.5 lbs really doesnt feel like much, I mean most people pick up 5-15 lb items all the time and dont think much of it. Anyhow, without knowing the thickness of the tube, and some way of estimating the yokes on the end, it really is pointless to try and calculate the rotational inertia with blanket statements. I am not about to cut both of mine in half just to see. Maybe you could stand on a ladder and spin them around and see which you like better. (that was a joke) anyhow, as for me, I am liking the aluminum one. Especially since my other one didnt run this smooth. And yes, I am a Mechanical Engineer.
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Well, the ex-Ford driveline engineer who gave me all the skinny on this **** some time ago (he used to post here, name was BillW, knew his **** up, down and sideways) said that when all is said and done the two shafts are very close in rotational inertia (I said "same" to save space), and among other things the aluminum shaft is NOT "better balanced" as many people believe, and that its primary benefit was changing the vibrational characteristics of the system.
His point about inertia was that a lot of people thought the lighter weight helped reduce driveline hp loss and aid in acceleration but that was not the case, due to the lighter weight being offset by the larger diameter = very similar polar moment = takes virtually the same power to get it moving
His point about inertia was that a lot of people thought the lighter weight helped reduce driveline hp loss and aid in acceleration but that was not the case, due to the lighter weight being offset by the larger diameter = very similar polar moment = takes virtually the same power to get it moving
MFE, you are going by hearsay with no backup versus actual experience with backup.
Here are some dynos with a carbon fiber one...which is a little lighter than the aluminum
![Image]()
and here is an article to read:
http://www.acpt.com/article1.html
another..infact this one they WEIGHED the 2 driveshafts and came up with the EXACT weight difference (8.5 lighter) that I mentioned above:
http://neptune.spacebears.com/cars/stories/scdrive.html
Just for kicks, before installing the new driveshaft we weighed them. The stock steel Ford driveshaft was 22.5 lbs. and the aluminum Ford Motorsports shaft was 14.0 lbs., a significant 8.5 lbs. lighter! The effect of the weight is magnified in a driveshaft, since it spins; the lighter shaft requires less energy to overcome its inertia.
a Messageboard User response:
http://www.wisvtoa.com/wisvtoavb/showthread.php?threadid=32&highlight=aluminum+driveshaft
Here are some dynos with a carbon fiber one...which is a little lighter than the aluminum
and here is an article to read:
http://www.acpt.com/article1.html
another..infact this one they WEIGHED the 2 driveshafts and came up with the EXACT weight difference (8.5 lighter) that I mentioned above:
http://neptune.spacebears.com/cars/stories/scdrive.html
Just for kicks, before installing the new driveshaft we weighed them. The stock steel Ford driveshaft was 22.5 lbs. and the aluminum Ford Motorsports shaft was 14.0 lbs., a significant 8.5 lbs. lighter! The effect of the weight is magnified in a driveshaft, since it spins; the lighter shaft requires less energy to overcome its inertia.
a Messageboard User response:
http://www.wisvtoa.com/wisvtoavb/showthread.php?threadid=32&highlight=aluminum+driveshaft
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You, however, are comparing apples to oranges. It's not about the static weight. You may very well be right that the aluminum DS is 8.5 lbs lighter didn't feel like it to me but then again I didn't take the time to weigh them so I'll take your word for it.
But your dyno graph showing a comparison between carbon fiber and steel is totally irrelevant to the conversation about the benefits of the FRPP aluminum shaft over the stock steel one. Why? Because IT'S NOT ABOUT THE STATIC WEIGHT. It's about polar moment of inertia, and no offense but I'll take the word of an engineer who worked on the calculations with the actual products in question over anybody else's word and he demonstrated that net/net the FRPP aluminum driveshaft offers no discernable power advantage over the stock steel one, because its increase in diameter offsets any gain in weight.
I don't know anything about the physics behind the carbon fiber one, and I don't doubt the dyno results for one second, but you can't take the dyno results for that shaft and say they're comparable to the aluminum one. Matter of fact, knowing what I know about the similarities in performance between the AL one and the steel one I'd say all that proves is that the CF one is better than the AL one by far.
And this is not "hearsay with no backup", I had the calculations and the conversations with the engineer I'm talking about saved but I lost it in a computer changeover last year. But I'm not just pulling this out of my ass.
But your dyno graph showing a comparison between carbon fiber and steel is totally irrelevant to the conversation about the benefits of the FRPP aluminum shaft over the stock steel one. Why? Because IT'S NOT ABOUT THE STATIC WEIGHT. It's about polar moment of inertia, and no offense but I'll take the word of an engineer who worked on the calculations with the actual products in question over anybody else's word and he demonstrated that net/net the FRPP aluminum driveshaft offers no discernable power advantage over the stock steel one, because its increase in diameter offsets any gain in weight.
I don't know anything about the physics behind the carbon fiber one, and I don't doubt the dyno results for one second, but you can't take the dyno results for that shaft and say they're comparable to the aluminum one. Matter of fact, knowing what I know about the similarities in performance between the AL one and the steel one I'd say all that proves is that the CF one is better than the AL one by far.
And this is not "hearsay with no backup", I had the calculations and the conversations with the engineer I'm talking about saved but I lost it in a computer changeover last year. But I'm not just pulling this out of my ass.
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So if we drive the diameter to zero... do we get a shaft that rotates by itself??MFE said:
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I still like the spin them both around in your hand to see which one you like better idea.
He probably is right that its not a big help. I mainly wanted mine because my other one was not smooth and it looks cool when I am working under the car I guess. I still say they arn't the same, but he isnt saying that either... But its not like my aluminum driveshaft just made my stock mustang run 9's or anything. Now if I had put some Type R racing stickers on the side, thats another story.
He probably is right that its not a big help. I mainly wanted mine because my other one was not smooth and it looks cool when I am working under the car I guess. I still say they arn't the same, but he isnt saying that either... But its not like my aluminum driveshaft just made my stock mustang run 9's or anything. Now if I had put some Type R racing stickers on the side, thats another story.
...just a thought....but two comparison points of "brand a" vs. "brand b" are not statistically enough evidence to sway my belief.
In a natural system it would be helpful to know the standard deviation over a series of at least 25 runs (on the dyno). This way you could more accurately determin the actual affect of the new shaft vs. the old.
In a natural system it would be helpful to know the standard deviation over a series of at least 25 runs (on the dyno). This way you could more accurately determin the actual affect of the new shaft vs. the old.
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No flames inteanded, but if there's little to no difference, why did Ford go through the trouble and expense of changing to an aluminum one on the later model Lightnings, rather than keeping the steel one that was already in production?
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I'm not sure. Why'd they use them on Cobra R's? All I can tell you is that based on theory and facts if anybody tries to tell you they measured an increase in performance along with their decrease in vibes...they're full of **** or wishful thinking.
Marketing the Lightening product (or any other product) does consider the "hype" (wants) of its consumer base. For performance reasons or not...if customers want it, they will sell it to you.Blue'87GT said:
It's like those discusting lightening euro tail lights. God damn I hate the look of those...but it's all "the rage". maybe the same was (is) true for the alum. drive shaft?
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This is my experience : I track tested mine. Went from stock with no vibes and (really no reason to change) to buying an aluminum driveshaft with zero improvments. Not anywhere. Car was just as smooth as before. Ran 10.70's before and after . I am sure on other cars its different, but this how mine was. I think my weight difference is about 6lbs. Like MFE said, it more for vibrations than anything.
I weighed mine when I installed it. (Installed to fix vibration problem). The difference was 6 pounds. Production differences might account for the 8.5 vs. 6 vs. 4 lb differences cited by different people with all the possible combinations out there; 5 speed, Auto, 5.0, 4.6 etc.
MFE makes a good point about polar moment of inertia, but without cutting them in half and measuring diameter and wall thickness it is a little hard to calculate the difference. My aluminum driveshaft was 4" dia. vs. 3.5" stock; significant, but not huge. The aluminum shaft is 14% larger in diameter, but 33% lighter (12 vs. 18 lb). The weight includes the yokes at both ends, which is pretty much equal for both shafts. Take that away, and the aluminum shaft is probably 50% lighter.
There is another thing to consider besides rotating inertia. Half the weight of the driveshaft is unsprung weight. So if you save 6 pounds, you are reducing unsprung weight by 3 pounds.
MFE makes a good point about polar moment of inertia, but without cutting them in half and measuring diameter and wall thickness it is a little hard to calculate the difference. My aluminum driveshaft was 4" dia. vs. 3.5" stock; significant, but not huge. The aluminum shaft is 14% larger in diameter, but 33% lighter (12 vs. 18 lb). The weight includes the yokes at both ends, which is pretty much equal for both shafts. Take that away, and the aluminum shaft is probably 50% lighter.
There is another thing to consider besides rotating inertia. Half the weight of the driveshaft is unsprung weight. So if you save 6 pounds, you are reducing unsprung weight by 3 pounds.
Ford has been using an aluminum driveshaft on the plain-jane F-150 for years, including the six cylinder models. I doubt they did it for marketing hype on those vehicles.
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Thanks techguy !
Good info
Good info
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What we are failing to realize here is the origin of the aluminum shaft. It was never specifically designed by Ford to fit the fox platform. That was just a happy coincidence. The driveshaft was originally made for the Lincoln Town Car. Since we all know what hot rods they are, I've gotta beleive that any performance return from them is purely coincidence. This is just one of many "carry over" parts from the SVO days. Most parts then were obsolete to most, but useful to others. If anybody does not beleive me, then just go down to your local junk yard and buy a used TC shaft.
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Hey ID... What part of Portland? Euro's don't do it for me, either. I'm at lower river road every once in a while. PDX int'l raceway sometimes, and Woodburn a couple times a season.
Ford Motorsport's heavy-duty aluminum driveshaft assembly is made from 3 1/2 in. diameter, .114 in-wall, steamless 6061-RT62 aluminum tubing to stand up to race abuse. Built to stock (45 1/2 in.) length to accept stock Spicer 1330 U-joints, they are easy bolt-in replacements.
I don't see what the big deal is.... AL driveshafts kick a$$. For bone stock cars, I think it would be a silly upgrade - but it's not far down on the list of things to do. I don't think we are failing to realize what they are for; they are a cheap way to upgrade your car. They may not improve performance, but they are a sure way to improve reliability at the track.... Pretty good at fixing vibes also, of course. For $170.... shipped.FordRacer9 said:
Here's what you need, although I wouldn't waste my time calculating the benefit.... It is there. Thank you Summit:
Ford Motorsport's heavy-duty aluminum driveshaft assembly is made from 3 1/2 in. diameter, .114 in-wall, steamless 6061-RT62 aluminum tubing to stand up to race abuse. Built to stock (45 1/2 in.) length to accept stock Spicer 1330 U-joints, they are easy bolt-in replacements.
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