PST Carbon Fiber Drive Shaft Installed

[Captain Insano]

This.... there are examples of aluminum DS offerings on the STi that require tunnel pounding with your choice of heavy tooling just to make it fit. I am sold on CF DS since OEM usage on Nissan sports cars for quite some time as Kirill mentioned.

[twincamRob]

Originally Posted by RallySport Direct

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.

My old S2000 had a steel driveshaft without a carrier bearing as well as my VG30 swapped S13. Not to mention about every pickup truck out there...

[Eau Rouge]

There seems to be an overall lack of understanding around the materials science in general. Just for fun, I'm going to toss in the fact that carbon fibers, in and of themselves, provide nearly no structural strength in loose form. The critical aspects of orienting the fibers to support the intended loads, the molecular properties of the resin that holds the fibers in the intended positions and the processes by which the manufacturing in undertaken all help to define the properties of the final product.

Having said that, two CF driveshafts that look the same on the surface could be entirely different when analyzed in depth. Learn actively, possess more knowledge, buy intelligently...

[RallySport Direct]

Originally Posted by twincamRob

My old S2000 had a steel driveshaft without a carrier bearing as well as my VG30 swapped S13. Not to mention about every pickup truck out there...

The S2K shaft is about half the length of the BRZ/FR-S shaft and that is a very important factor to consider. Most pickup driveshafts are about twice the diameter and roughly the same length as our driveshafts, which is also something to take into account. I don't know about what I assume to be a custom driveshaft you were using in your S13, but there will always be an exception to everything.

The problem with a one piece heavy steel shaft is that it will vibrate and flex if the OD and wall thickness cannot support the weight. Maybe I should rephrase what I posted earlier. A one piece steel driveshaft in the BRZ/FR-S is not feasible because the tunnel is too narrow to house a shaft that would be thick enough to support it's own weight and you would be reducing performance by switching to a heavier shaft.

-Zach

[TuxedoCartman]

Thought I'd throw my review out for the carbon-fiber shaft, since I got mine installed earlier. It does make the car feel more... eager?... in the low-to-midrange, but the big benefit is how smooth everything is now. I mean, I'm no novice at rev-matching, but with this shaft on it's so easy to seamlessly match revs that I almost feel like I'm cheating. I'd give it my recommendation; $1000 well spent, in my opinion.

Now, to go get my wheels installed and see how much better it gets....

[FreshFRS]

Originally Posted by twincamRob

My old S2000 had a steel driveshaft without a carrier bearing as well as my VG30 swapped S13. Not to mention about every pickup truck out there...

S2k driveshaft was heavy though. i swapped to carbon fiber when i went turbo and cut shaft weight in half.

[msile]

Originally Posted by TuxedoCartman

Thought I'd throw my review out for the carbon-fiber shaft, since I got mine installed earlier. It does make the car feel more... eager?... in the low-to-midrange, but the big benefit is how smooth everything is now. I mean, I'm no novice at rev-matching, but with this shaft on it's so easy to seamlessly match revs that I almost feel like I'm cheating. I'd give it my recommendation; $1000 well spent, in my opinion.

Now, to go get my wheels installed and see how much better it gets....

+1

You said it well. This is what I have been trying to say....the car is eager
I have put on about 2000 miles since the install, still rattle and vibration free too. I wonder how much more noticeable the shaft would be with forced induction.

[d1ck]

Originally Posted by 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.

Since a driveshaft with a moment applied can essentially be considered a spring as long as the shear stress doesn't reach the yield stress, which would have the higher spring rate? Stock, CF or Aluminium? By this I mean: Were you to apply 100 ft-lbs of torque to all three, which would twist more or less?

[RallySport Direct]

The Carbon shaft should give the most twist compared to any others on the market. The Carbon shafts do a great job of being like a spring in that they can absorb a great amount of force, and then twist back to their original shape/position. You can really feel this on the car under hard shifts or drag type launches, the initial shock in the drivetrain is greatly reduced, and then you feel the carbon shaft give the car a bit of a "nudge" as it unloads the energy back to the drivetrain. Pretty cool feeling overall

Hope this helps!
Thanks,
Rick

[Lonewolf]

What happened to the AT version of this driveshaft? I followed the links in this thread but they were inactive...

[RallySport Direct]

Originally Posted by Lonewolf

What happened to the AT version of this driveshaft? I followed the links in this thread but they were inactive...

We closed them down due to the lack of committed buyers in the group buy. I feel like the timing was off due to the Holidays and Winter. We will start up another Group Buy thread for the AT drive shaft later down the road. I'm thinking this one will go much better due to more cars being on the road, and generally more interest all around. We will keep you posted.

Thanks,
Rick

[robispec]

I LOVE mine!

[RallySport Direct]

Originally Posted by robispec

I LOVE mine!

We have one on both our Shop STi and BRZ, and I am itching to get one for my personal car as well, just all around a great modification for so many reasons!

Thanks!
Rick

[DSOmegaX]

any chance we can revive that group buy for the AT one?