PST Carbon Fiber Drive Shaft Installed

[Jeff86]

Originally Posted by TuxedoCartman

Cool. I'm sold... order placed!

Ballin! I want one of these too and after I've lightened up my wheels this is definitely on the list. Congratz man

[TuxedoCartman]

Originally Posted by Jeff86

Ballin! I want one of these too and after I've lightened up my wheels this is definitely on the list. Congratz man

If the driveshaft got shipped out today, it'll be arriving at the same time as my wheels I've been waiting six months for! My baby girl's getting a full makeover next week!

[twincamRob]

Originally Posted by RallySport Direct

I see what you are saying, but I respectfully disagree.

Well looking at that pic it looks like 'our' carrier bearings are smaller than what I'm used to seeing (S chassis, DSM, etc...) so I retract my statement about "most of the weight reduction being from removing the carrier bearing".

But it goes without saying that a less 'exotic' 1 piece steel or aluminum driveshaft will have pretty close to the same savings for far cheaper.

[TuxedoCartman]

Originally Posted by twincamRob

Well looking at that pic it looks like 'our' carrier bearings are smaller than what I'm used to seeing (S chassis, DSM, etc...) so I retract my statement about "most of the weight reduction being from removing the carrier bearing".

But it goes without saying that a less 'exotic' 1 piece steel or aluminum driveshaft will have pretty close to the same savings for far cheaper.

Yes, but there are other benefits to a carbon fiber shaft besides being lighter in weight (which is still pretty damn substantial, compared to weight savings on other rotating bits of mass like the wheels). Apparently they are more elastic, and can twist more without failing than an aluminum shaft. The same elasticity apparently makes smooth shifting easier too, from what I've read.

I've driven cars with carbon fiber driveshafts, but never replaced a stock steel one with carbon fiber. I'm eager to see the difference for myself. Is it worth $1000 to some people? Probably not. But then again, there's a lot of money people spend on their cars that I can't fathom myself, so each to their own.

[RallySport Direct]

Originally Posted by TuxedoCartman

Yes, but there are other benefits to a carbon fiber shaft besides being lighter in weight (which is still pretty damn substantial, compared to weight savings on other rotating bits of mass like the wheels). Apparently they are more elastic, and can twist more without failing than an aluminum shaft. The same elasticity apparently makes smooth shifting easier too, from what I've read.

I've driven cars with carbon fiber driveshafts, but never replaced a stock steel one with carbon fiber. I'm eager to see the difference for myself. Is it worth $1000 to some people? Probably not. But then again, there's a lot of money people spend on their cars that I can't fathom myself, so each to their own.

Yeah, I really liked it in our BRZ. I am never going to say that it makes a night and day difference to the power or acceleration of the car, but all around I think it is a fantastic mod. It helped with the power delivery, smoothness of the drivetrain, and while I have not done any really hard drag style launches, it does seem to give a bit more traction and "oomph" off the line, and you can feel the driveshaft load and unload a bit, it's a pretty cool feeling!

Thanks,
Rick

[DSOmegaX]

And I am going to shamelessly plug that people with AT get in that order in the classified section so we can get them made and shipped out!

[ngabdala]

What shame? I paid $220 for a custom shift knob from WC Latheworks

Originally Posted by DSOmegaX

And I am going to shamelessly plug that people with AT get in that order in the classified section so we can get them made and shipped out!

[DSOmegaX]

Haha no shame in that. I meant shameful as in I selfishly want people to hurry up and place an order so they can start making them. I want my drive shaft!

[Captain Insano]

Ditto man. I want one too.

[RallySport Direct]

Originally Posted by twincamRob

Well looking at that pic it looks like 'our' carrier bearings are smaller than what I'm used to seeing (S chassis, DSM, etc...) so I retract my statement about "most of the weight reduction being from removing the carrier bearing".

But it goes without saying that a less 'exotic' 1 piece steel or aluminum driveshaft will have pretty close to the same savings for far cheaper.

An aluminum shaft will be cheaper and lighter, but it will be larger. I don't know how much room an aluminum shaft would leave for exhaust clearance, but it won't be much if any.

A steel driveshaft is going to be too heavy to for a 1 piece shaft and you need a carrier bearing to support that kind of weight. Aluminum and steel will be quite a bit cheaper, but carbon fiber does have quite a few advantages.

We actually did a writeup that covers both aluminum and carbon fiber driveshafts and the differences between them. I will post a few highlights from our overview.

Carbon and Aluminum Drive Shaft Overview

• CF has a smaller OD, which means direct replacement with no modifications. Some applications require modification to heat shields or transmission tunnels to allow adequate clearance for the larger OD Aluminum shaft.
• CF shafts are capable of higher speeds
• The CF shaft can twist about 2X as much compared to the aluminum counter part before it fails from sheer stress
• When the CF shaft fails, the fibers will come apart and un-wind. When an Aluminum shaft fails…well you have a 14lb sledge hammer spinning at over 1000RPM going to town under your car

Aluminum does have a couple advantages over carbon fiber though

• An equivalent CF shaft will be about 5-10% heavier then a Aluminum counter part

• Aluminum shafts are only about 30-50% of the price of the CF unit

Let us know if you guys have any questions about this
Thanks,
Zach

[d1ck]

Originally Posted by RallySport Direct

An aluminum shaft will be cheaper and lighter, but it will be larger. I don't know how much room an aluminum shaft would leave for exhaust clearance, but it won't be much if any.

A steel driveshaft is going to be too heavy to for a 1 piece shaft and you need a carrier bearing to support that kind of weight. Aluminum and steel will be quite a bit cheaper, but carbon fiber does have quite a few advantages.

We actually did a writeup that covers both aluminum and carbon fiber driveshafts and the differences between them. I will post a few highlights from our overview.

Carbon and Aluminum Drive Shaft Overview

• CF has a smaller OD, which means direct replacement with no modifications. Some applications require modification to heat shields or transmission tunnels to allow adequate clearance for the larger OD Aluminum shaft.
• CF shafts are capable of higher speeds
• The CF shaft can twist about 2X as much compared to the aluminum counter part before it fails from sheer stress
• When the CF shaft fails, the fibers will come apart and un-wind. When an Aluminum shaft fails…well you have a 14lb sledge hammer spinning at over 1000RPM going to town under your car

Aluminum does have a couple advantages over carbon fiber though

• An equivalent CF shaft will be about 5-10% heavier then a Aluminum counter part

• Aluminum shafts are only about 30-50% of the price of the CF unit

Let us know if you guys have any questions about this
Thanks,
Zach

How does the shear strength of the CF compare to the Aluminium? You mention that the CF one can twist more before failure, but so would one made of rubber. This isn't really a good indication of it's strength.

[mike2100]

Originally Posted by RallySport Direct

• CF shafts are capable of higher speeds

Can the aluminum driveshaft spin fast enough for this car? If so this point is moot.

[RallySport Direct]

Yield strength is based on the materials Youngs modulus of elasticity and correlates to stress and strain that a material can withstand before yield strength is reached. Yield strength is the materials proper to withstand loading prior to deformation occurring and be able to return back to its original yield property and shape. Going beyond this point will result in work hardening of the material, beyond that you have your ultimate yeild where the materials property is gone out the window. That right there is a quick and dirty overview of 2 Material Science and Strength of Materials college level classes hahaha.

Ill do my best to put it into simple terms for easy understanding. For instance ceramics (think of your coffee cup) are very strong, however they are very brittle. When high load is applied rapidly it will fracture easily (dropping the cup) into many different pieces, but if you apply a large load over a small time frame the cup will hold up quite a bit of weight.
Now take the example you provided, simple rubber (rubber band, as we can get into polymers and would be beyond the scope of easy understanding unless you have a good background in material science at which point this explanation wouldn't be needed). It will deform and stretch over 3 times its size, when it does fracture you have a nice even break and very little shrapnel. As you can imagine if you have a rubber shaft it would twist and twist and twist, you have a ceramic shaft and it will fracture easily.

Now......think of carbon shafts as a very very very good rubber band that will have higher amount of twist then aluminum of up to 30 degrees if I remember correctly (this depending on resin used, carbon lay direction, and layers of carbon) along with having a higher resistance to fracture as a result. Where as aluminum shaft is a lower angle of only about 5-8 degrees, showing that is has a lower Proportionality limit. Yet Carbons ability in this application to transfer energy, have a higher critical speed as a result of the harmonics that it can withstand before hitting natural frequency, and its ability to be manufactured in various sizes easier make it ideal for this application. Problem with aluminum is you can only get it in industry standard sizes, 2", 3", ect for instance, and with certain wall thickness. To be able to withstand torsion and deformation it needs a wall thickness that can support that, and to get that wall thickness you need to go to a larger pipe size.

So I hope you can see the benefit of these units. Nissan has been using them on 350Z's sense day one, they are used on GTR's and many other sports cars for these reasons.

Is a carbon shaft a product for everyone? No. Same way that a body kit, or knock off wheels, and LED's are not for everyone. But this product works great and is for a consumer who can appreciate fine tuning the car and increasing response (quality over quantity). Ive used them on my personal car, we have them on both our shop cars, and I have many customers who use them on everything from street cars to 600+ HP Time attack cars. They simply work due to the carbon fibers vast benefits as a material, compact design, and the safety factor.


If you guys really want more info about material properties and loading I can blow the dust off the books at my house on these subjects and go a bit more in depth. Only problem is it might confuse more people instead of educate them unless they have a background of previous exposure in chemicals, material science, and strength of materials.

Kirill
RallySportDirect.com

PS. Dont get me wrong Aluminum shafts have their place in the market, its just that technology advances of carbon materials being used make it much more desirable is many applications. About the only draw back to carbon is Cost. If carbon was made cheaper it would be used on production car chassis, there is a reason why most modern day super cars use carbon and exotic metals for construction. If carbon didnt have an advantage race teams, major manufactures (not just in the automotive industry), and millitary would not be spending billions uppon billions on research.

[RallySport Direct]

Originally Posted by mike2100

[/LIST]Can the aluminum driveshaft spin fast enough for this car? If so this point is moot.

At stock HP probably not, but there is no point in designing parts for stock HP limitations. When we worked with PST on producing this shaft, we made sure that it can withstand hitting redline in 6th gear+ some.

Also keep in mind aluminum shafts need to be larger in size to withstand the required sheer stress. The BRZ has a narrow tunnel, so how excited would you be to take a sledge hammer to your brand new car to widen the tunnel to ensure you have 2-3" of clearance between the shaft and the chassis to allow for the shaft to twist and vibrate

Kirill
RallySportDirect.com