pulled the trigger on a DSS driveshaft

[steveespo]

I have had the DSS aluminum shaft since December and about 1200 total miles, 115 track miles. No vibration, noise or contact with the chassis or exhaust. Installation is straight forward, you need to remove 1 side of your exhaust pipes between the muffler and h pipe. Remove the stock shaft, bolts have thread locking compound so they are tight, make sure you have the correct 12 point socket for the front flange bolts. Next clean the old bolts and run them in and out of the flanges to remove as much of the old thread lock as possible and clean out with brake cleaner. You have to install the new rear axle flange adapter with the Allen cap screws provided torque per instructions (59 ft/lbs) I believe then install shaft. Using red locktite The stock front bolts are reinstalled, don't torque yet and then lift the rear of the shaft into place aligning the CV joint with the holes in the adapter flange. Install those bolts with red locktite and torque in 2 steps in a criss cross fashion to 30 then 59 ft/lbs. torque the 4 front bolts to 83 ft/lbs. Reinstall exhaust and test drive, there should be no issues. Enjoy the reduced weight , drive line clunks and improved acceleration.
Steve

 

[Fat Boss]

I have had the DSS aluminum shaft since December and about 1200 total miles, 115 track miles. No vibration, noise or contact with the chassis or exhaust. Installation is straight forward, you need to remove 1 side of your exhaust pipes between the muffler and h pipe. Remove the stock shaft, bolts have thread locking compound so they are tight, make sure you have the correct 12 point socket for the front flange bolts. Next clean the old bolts and run them in and out of the flanges to remove as much of the old thread lock as possible and clean out with brake cleaner. You have to install the new rear axle flange adapter with the Allen cap screws provided torque per instructions (59 ft/lbs) I believe then install shaft. Using red locktite The stock front bolts are reinstalled, don't torque yet and then lift the rear of the shaft into place aligning the CV joint with the holes in the adapter flange. Install those bolts with red locktite and torque in 2 steps in a criss cross fashion to 30 then 59 ft/lbs. torque the 4 front bolts to 83 ft/lbs. Reinstall exhaust and test drive, there should be no issues. Enjoy the reduced weight , drive line clunks and improved acceleration.
Steve

Good report Steve! From what the Ford engineer told us, they wanted to use a one piece alum DS but they couldn't get the NVH to meet the Ford specs. The concept of a two piece is that you have less total run-out with the bearing mid-way, but the penalty is more weight. I'd love to try an AL one. Anyone try the Shelby unit from the new GT350's?

 

[Justin]

I did a search, and saw what 5 dot 0 posted, maybe I was just remembering that.

https://trackmustangsonline.com/boss-302-general-forum/top-speedrev-limiter/


What does the R and the new GT500 have?


R has this one piece

http://www.fordracingparts.com/parts/part_details.asp?PartKeyField=11824


But I'm not an engineer, really I don't know which is better. Just usually more joints = less strong

the 2013 GT500 has a carbon fiber driveshaft from the articles I have read

 

[Tflong24]

I have had the DSS aluminum shaft since December and about 1200 total miles, 115 track miles. No vibration, noise or contact with the chassis or exhaust. Installation is straight forward, you need to remove 1 side of your exhaust pipes between the muffler and h pipe. Remove the stock shaft, bolts have thread locking compound so they are tight, make sure you have the correct 12 point socket for the front flange bolts. Next clean the old bolts and run them in and out of the flanges to remove as much of the old thread lock as possible and clean out with brake cleaner. You have to install the new rear axle flange adapter with the Allen cap screws provided torque per instructions (59 ft/lbs) I believe then install shaft. Using red locktite The stock front bolts are reinstalled, don't torque yet and then lift the rear of the shaft into place aligning the CV joint with the holes in the adapter flange. Install those bolts with red locktite and torque in 2 steps in a criss cross fashion to 30 then 59 ft/lbs. torque the 4 front bolts to 83 ft/lbs. Reinstall exhaust and test drive, there should be no issues. Enjoy the reduced weight , drive line clunks and improved acceleration.
Steve

.

Thanks for the detailed install process. Dumb question, do they send instructions with all the torgue specs you listed?

 

[steveespo]

There is actually a sticke on the rear hub adapter reminding you to torque to 59 ft/lbs before bolting the CV joint to it also at 59 ft/lbs with the supplied bolts. The front flange torque I got from the Mustang sop manual available here:
http://www.allfordmustangs.com/forums/2011-mustang-gt-tech/263742-line-fully-browseable-2011-mustang-service-manual.html
you have to sign up on the forum to read it but very helpful.
Steve

 

[2012YellowBoss]

Great info Steve. I use this for a shop manual for now. I hope to see a 2012 manual soon.

http://iihs.net/fsm/?dir=711

 

[Justin]

I have heard that rumor but have never seen the official reason for the speed limiter being the shaft. The 302S comes with a two piece driveshaft also.

well from all the articles I have read the reason for the heavy two piece was NVH. Hell guys were breaking them on the dyno once they put some power to them. and the V6 is even worse. take it above 120 and it will explode videos of that are all over the youtube.
[youtube]http://www.youtube.com/watch?v=LZXBjVIrR08[/youtube]

[youtube]http://www.youtube.com/watch?v=1_AjKt-KSNU[/youtube]

 

[roketman]

Didn't Ford say that the shaft is the main reason they are capped at 155 (or something like that) mph? But they used it because of NVH. I could be remembering wrong but I know a lot of people say not to use the jointed one for high speeds. Plus with the joint, they can slip out of loops if you have them.

You are correct! Its considered critical.Let s wait and see how it works for others!

 

[jeepinocala]

So what you are showing us is going to the one piece is not only fast by weight loss but also safer since the stock drive shafts can fail right?

 

[CaliMR]

If you get a Shaftmasters, make sure it is the revised ones. The original ones had bad welds or something.

 

[BlackNDecker]

[quote author=boss2511]
As for what causes the "gain" it is rotating weight. Rotational mass makes a huge difference. Good example rev a car with a stock steel flywheel rev the same car with an alum flywheel. the alum flywheel will spin up much much faster. But alum flywheels have there down falls mostly in drag racing cause they dont have the inertia to over come the rest of the car at rest and make the car bog really easy.

[/quote]

I do not believe the difference in peformance can be attributed to "rotating weight." Why? Because the math debunks this theory.

I posted this over on svtperformance.com:

People seem to mindlessly recite that lightweight driveshafts decrease "rotational weight" thereby improving "rotational acceleration". In mathematical terms this is referred to as decreasing moments of inertia. Imagine a moment of inertia as the spoke of a wooden wagon wheel.


"The moment of inertia of an object about a given axis describes how difficult it is to change its angular motion about that axis. Therefore, it encompasses not just how much mass the object has overall, but how far each bit of mass is from the axis. The further out the object's mass is, the more rotational inertia the object has, and the more torque (force* distance from axis of rotation) is required to change its rotation rate."

The formula is

Where I = inertia, m = mass, and r = radius. You can see in the formula that radius is "squared" and therefore has a much larger influence on inertia (or resistance to acceleration).

Inertia is related to acceleration by the following formula:
I = T/a

I = inertia, T = torque, a = acceleration

The point of all of this is that the radius of the driveshaft is small so any reduction in weight will have a VERY VERY VERY SMALL effect on acceleration (you would get the same benefit from removing the spare tire...which is free:rolling. Bonus points for recognizing that 20" wheels are "for looks" and the weight of the tire is more important than the weight of the wheel.

 

[Tflong24]

[quote author=boss2511]
As for what causes the "gain" it is rotating weight. Rotational mass makes a huge difference. Good example rev a car with a stock steel flywheel rev the same car with an alum flywheel. the alum flywheel will spin up much much faster. But alum flywheels have there down falls mostly in drag racing cause they dont have the inertia to over come the rest of the car at rest and make the car bog really easy.

I do not believe the difference is "rotating weight." Why? Because the math deb

I posted this over on svtperformance.com:

People seem to mindlessly recite that lightweight driveshafts decrease "rotational weight" thereby improving "rotational acceleration". In mathematical terms this is referred to as decreasing moments of inertia. Imagine a moment of inertia as the spoke of a wooden wagon wheel.

For your information...
"The moment of inertia of an object about a given axis describes how difficult it is to change its angular motion about that axis. Therefore, it encompasses not just how much mass the object has overall, but how far each bit of mass is from the axis. The further out the object's mass is, the more rotational inertia the object has, and the more torque (force* distance from axis of rotation) is required to change its rotation rate."

The formula is

Where I = inertia, m = mass, and r = radius. You can see in the formula that radius is "squared" and therefore has a much larger influence on inertia (or resistance to acceleration).

Inertia is related to acceleration by the following formula:
I = T/a

I = inertia, T = torque, a = acceleration

The point of all of this is that the radius of the driveshaft is small so any reduction in weight will have a VERY VERY VERY SMALL effect on acceleration (you would get the same benefit from removing the spare tire...which is free:rolling. Bonus points for recognizing that 20" wheels are "for looks" and the weight of the tire is more important than the weight of the wheel.

[/quote]

You can do all the math you want, common sense says lay a round 10 foot long anything that weighs 20 pounds, twist it as fast as you can. Take the same length that weighs 10 pounds. I bet you can turn it with less effort and faster. That's the point. With your "math" lightweight flywheels would serve no purpose. Tell that to any race team. Not to mention the extra joints. If heavy 2piece driveshafts were the way to go, I think you would see them on hi po track cars! Don't think so.

 

[BlackNDecker]

[quote author=Tflong24]
You can do all the math you want, common sense says lay a round 10 foot long anything that weighs 20 pounds, twist it as fast as you can. Take the same length that weighs 10 pounds. I bet you can turn it with less effort and faster. That's the point.
[/QUOTE]
Mathematics and physics got us to the moon in a tin can....but you would dismiss all that for a ridiculous analogy???
Your analogy is ridiculous because it introduces additional forces like friction and fulcrums (something has to balance the rod while you twist it). In the vacuum of space you would not be able to appreciate a 25 lb difference simply by rotating it.

LOL...try again.

With your "math" lightweight flywheels would serve no purpose. Tell that to any race team. Not to mention the extra joints. If heavy 2piece driveshafts were the way to go, I think you would see them on hi po track cars! Don't think so.

Wrong again, you don't understand the math.

I'm not saying that decreasing the moment of inertia (i.e. the sum of mass x radius squared) will not improve acceleration...of course it will (smaller, lighter weight wheels & tires will dramatically improve acceleration and all around performance). Instead, what I am saying is that the radius of a drive shaft is so small that reducing it's weight will not affect the moment of inertia (and by extension rotational acceleration) to any measureable degree.

I never said "a heavy driveshaft was the way to go"...all I'm saying is that the improvement in peformance cannot be attributed solely to rotational acceleration. That is an oversimplification. A flywheel has a much larger radius, therefore decreasing the mass of a flywheel WILL improve the moment of inertia and angular acceleration.

 

[TMSBOSS]

[quote author=Tflong24]
You can do all the math you want, common sense says lay a round 10 foot long anything that weighs 20 pounds, twist it as fast as you can. Take the same length that weighs 10 pounds. I bet you can turn it with less effort and faster. That's the point.

Mathematics and physics got us to the moon in a tin can....but you would dismiss all that for a ridiculous analogy???
Your analogy is ridiculous because it introduces additional forces like friction and fulcrums (something has to balance the rod while you twist it). In the vacuum of space you would not be able to appreciate a 25 lb difference simply by rotating it.

LOL...try again.

With your "math" lightweight flywheels would serve no purpose. Tell that to any race team. Not to mention the extra joints. If heavy 2piece driveshafts were the way to go, I think you would see them on hi po track cars! Don't think so.

Wrong again, you don't understand the math.

I'm not saying that decreasing the moment of inertia (i.e. the sum of mass x radius squared) will not improve acceleration...of course it will (smaller, lighter weight wheels & tires will dramatically improve acceleration and all around performance). Instead, what I am saying is that the radius of a drive shaft is so small that reducing it's weight will not affect the moment of inertia (and by extension rotational acceleration) to any measureable degree.

I never said "a heavy driveshaft was the way to go"...all I'm saying is that the improvement in peformance cannot be attributed solely to rotational acceleration. That is an oversimplification. A flywheel has a much larger radius, therefore decreasing the mass of a flywheel WILL improve the moment of inertia and angular acceleration.


[/quote]

BND

Does the math above take into consideration the frictional loss of the carrier bearing as well as the loss the change of direction, although slight, makes on the equasion? :-[

I am not a math wiz, just a guy wondering if the equasion above takes all factors into consideration. Yes, you seem to have accounted for the weight decrease not having effect assuming the the only effect is the drop in weight.

How do we account for the loss of drag accountable to the removal of the bearing and joint associated with the stock shaft??

Thanks

 

[BlackNDecker]

TMSBOSS,

Good question...I will be honest, I do not have any experience with swapping drive shafts. Your question may explain the apparent "smoothness" of the drivetrain felt after swapping over to a DSS brand driveshaft. But remember, drag related to a bearing has nothing to do with decreasing rotational weight...so theoretically the same benefits could be obtained with an identical weight steel driveshaft with the same modifications to the bearing and joint.

I can assure you I'm not trying to troll...this topic has just become an interest of mine. There has to be another explanation for the "supposed" increase in performance other simply a decrease in rotational weight. Again, the math does not support this pervasive claim.

I would love to be proven wrong ;D

 

[Justin]

TMSBOSS,

Good question...I will be honest, I do not have any experience with swapping drive shafts. Your question may explain the apparent "smoothness" of the drivetrain felt after swapping over to a DSS brand driveshaft. But remember, drag related to a bearing has nothing to do with decreasing rotational weight...so theoretically the same benefits could be obtained with an identical weight steel driveshaft with the same modifications to the bearing and joint.

I can assure you I'm not trying to troll...this topic has just become an interest of mine. There has to be another explanation for the "supposed" increase in performance other simply a decrease in rotational weight. Again, the math does not support this pervasive claim.

I would love to be proven wrong ;D

its physics 101 simple as that. is it easier to swing a 10lb weight in a circle vise a 25lb weight? obviously the answer is yes.
http://en.wikipedia.org/wiki/Moment_of_inertia
http://www.ux1.eiu.edu/~cfadd/1150/09Rot/RotDyn.html
http://electron6.phys.utk.edu/101/CH2/rotational_mass.htm

 

[BlackNDecker]

I'm sorry but I'm not sure what the point of your post was? Your link shows the exact same equations that I posted above. Are you trying to disagree with the math or what?

 

[Justin]

I'm sorry but I'm not sure what the point of your post was? Your link shows the exact same equations that I posted above. Are you trying to disagree with the math or what?

the point is that reducing rotational mass in the drive train frees up horse power. the lighter the better. but I am done trying to explain why an alum driveshaft is better than the stock two piece steel driveshaft. so by all means leave the stock one on your car.

 

[BlackNDecker]

Eventually I plan to swap a cf driveshaft onto my car...I just want to explore the topic more fully. I think we are saying the same thing, however, I think you are oversimplifying the decrease in rotational mass. The distance the mass is from the center has a much much much larger contribution to inertia (and by extension of the math, angular acceleration). Again, referring to the equation, the further the weight is from the axis rotation...the greater is its contribution to inertia (and negatively effects angular acceleration). <-- read that last sentence again.

This is why getting lightweight tires will have a much greater impact on acceleration than lightweight wheels (but on a track car, tire grip trumps tire weight...so people rarely cross shop tires by weight). The fact that radius is the largest contributor to inertia, this is also why smaller overall diameter wheels have a much much greater impact on acceleration than lightweight wheels with similar overall diameter.

 

[Justin]

Eventually I plan to swap a cf driveshaft onto my car...I just want to explore the topic more fully. I think we are saying the same thing, however, I think you are oversimplifying the decrease in rotational mass. The distance the mass is from the center has a much much much larger contribution to inertia (and by extension of the math, angular acceleration). Again, referring to the equation, the further the weight is from the axis rotation...the greater is its contribution to inertia (and negatively effects angular acceleration). <-- read that last sentence again.

This is why getting lightweight tires will have a much greater impact on acceleration than lightweight wheels (but on a track car, tire grip trumps tire weight...so people rarely cross shop tires by weight). The fact that radius is the largest contributor to inertia, this is also why smaller overall diameter wheels have a much much greater impact on acceleration than lightweight wheels with similar overall diameter.

yeah we are saying the same thing. hence going for a 3.5" vs a 4" alum driveshaft. I think I read to many replies at once and just threw them altogether as "I dont get how a alum driveshaft frees up hp" type of thing. my bad been in the sun all day too layering on the zaino so thats my excuse lol