PST Carbon Fiber Drive Shaft Installed
 

Purchased from Rallysport. Great customer service!
I didn't feel like getting under the car again so I took it to Mr. Auto Clinic who, being meticulous, took under 30 minutes to swap it out and complete an oil change. It was that simple.

Measured 13.9 pounds to a T. I did not weigh the stock piece, but it is supposed to be 10.24 pounds lighter than stock according to Rallysport.

It is as the guys at Rallysport said. The car feels much peppier and it ties all my other mods together very well. The shifts are easier (less notchiness) too. I also did not feel any vibration through the RPM range.

CF Shaft Close-Up

http://i297.photobucket.com/albums/m...S/DSC01261.jpg
http://i297.photobucket.com/albums/m...S/DSC01256.jpg

http://i297.photobucket.com/albums/m...S/DSC01260.jpg

Stock Shaft

http://i297.photobucket.com/albums/m...S/DSC01263.jpg

http://i297.photobucket.com/albums/m...S/DSC01264.jpg

http://i297.photobucket.com/albums/m...S/DSC01265.jpg

http://i297.photobucket.com/albums/m...S/DSC01267.jpg

CF Shaft

http://i297.photobucket.com/albums/m...S/DSC01268.jpg

http://i297.photobucket.com/albums/m...S/DSC01269.jpg

http://i297.photobucket.com/albums/m...S/DSC01270.jpg

Cool mod. Any idea how much lighter this is than an aluminum driveshaft?

Nice! I'll go ahead and be "that guy". How much!?

Nope.

Thanks. More info and pricing here:

http://www.ft86club.com/forums/showthread.php?t=16029

Wow...$$$$$...

Looks awesome by the way!

Just a kidney :lol: Thanks.

Nice Mod! ;)

Sent from my GT-I9300 using Tapatalk 2

1100 bucks to lose over 10 lbs rotational mass. That's bordering on reasonable (compared to 800-1400 for wheels that drop 12-24 lbs). But I still like it. Props for doing this mod. I could see this on my future to do list, but probably when I run out of other things to do.

Wow, thanks for taking the time to do the write up and taking the awesome pictures. Glad you are enjoying the shaft as well, we are loving ours!

Thanks again!
Rick

After the differential gear ratio reduction is taken into account, the effective moment of inertia decrease is pretty small compared to wheels. Of course, wheels can only be made so light, but their effective "moment radius" is still larger.

True. I have lighter than stock wheels, pulley and the CF Shaft. The combo is pretty noticeable.

That must be pretty awesome. I personally wouldn't spend that money (aluminum makes more sense in this situation imo) but CF is always badass :D

Yeah too bad you have to get under the car to see it. :)

Who makes it in aluminum?

No one that I'm aware of, but I haven't really been following the aftermarket for this car since I got a different car.

Hopefully someone makes it in aluminum sometime, as that would be a lot more affordable.

I thought it worked the other way since the drive shaft is spinning 4.1 times faster that the wheels therefore reduction in the rotational inertia is 4.1 times more effective?

What's the diameter of the driveshaft? What's the diameter of the wheel? See what I'm getting at?

I guess I should've written "the effective moment of inertia decrease is still pretty small compared to that of a reduction of mass at the wheels"

Ahhh, sorry i did misunderstand you. And i absolutely agree with what you are saying. The shaft would have to be ~ 4.5" diameter to make the same difference as lighter wheels. Which is why a light weight flywheel is such a good upgrade, but that has been covered in other threads.

Well of course not all of the wheel's mass is on the outer diameter (whereas much of the driveshaft is) but yea I'd bet that the effective "average radius" is still bigger on the wheels.

I have to disagree on the aluminum. Carbon has very very good natural vibrational damping properties and is extremely resistant to fatigue. Additionally, carbon shafts do a great job of smoothing out the powertrain and making it a bit more forgiving. I'd be interested in carbon for this fact alone aside from the weight savings and aluminum will never be able to get anywhere close in that regard.

Nathan

I wish they made this for the AT guys and gals.

Yes, this is needed for an AT fit.

I don't think fatigue is a big issue for a driveshaft since the reverse loads are small and there's not much cycling going on, but I may be wrong. Also while carbon probably damps vibrations better than aluminum, aluminum is still an improvement over steel in that regard, I believe.

At least in the cycling world, aluminum frames are the absolute worst when it comes to vibration. Because they require thicker wall tubing and larger diameter tubing to reach the same strength (Aluminum is lower strength than steel obviously, but it is also much less dense so there's still potential weight savings over *most* steels.) they rattle you to death on rough roads.

Steel has a nice "hum" about it and a certain springyness. Carbon is like riding on a cloud, it damps everything out and also has a bit of spring.

Nathan

Hell yeah...

What you end up getting serial?

Is the shaft different for AT & MT?

Cool mod BTW. Maybe I'll work up to doing this, but I don't know if I can justify the cost for it TBH. :thumbup::happy0180:

According to RSD yes it is, probably in length and spline configuration.

Its hard to tell from the pics, but how close is it to the exhaust?

Far away. Same as stock..

Driveshaft $1,100 ... But the pool table in the photograph is Priceless$

Busted! I wanted good lighting ;)

Is it me or do you have a lift in your garage...

I tried, but the garage doors were in the way. I would have to modify it. Too much hassle.

Giggity

Never thought it was that easy to swap out. Very nice.

Any max torque numbers you can putt through it? With shop already putting 380+ wtq through a stock block when they start to build them it could end up being around 600. I drift and twisting aluminum shafts is pretty common once you start getting into the higher horse power in that type of environment.

From RallySport's Thread:

The shafts are rated at over 2700lbf/tq, in other words you have to do something crazy to break it!
PST has drag cars running in the 6 second 1/4 mile using the same shaft designs.

Cool thing about carbon fiber shafts..they twist a certain degree while staying in the elastic region of the sheer stress, meaning they take up shock and spring back to original shape.
One thing that simply blew me away was that the weak point on these shafts....the metal yokes on the end, and not the carbon. If you ever manage to break the yoke, well PST can make you a billet unit for you monster when that time comes :)

2700 will do... haha One other good thing about the flex would be the shock savings on the half shafts. Even though I want shock going through the drive train in certain situations the flex would theoretically help prevent the half shafts from snapping at higher horse power loads and increased tire size. pretty neat.

If we have enough interest for a AT unit we can get those made as well ;)

As for Aluminum vs Carbon, this is a write up I did going over both of them. This was done on our 2011 Sti shop car as the test mule but the exact same concepts apply.

http://theattack.rallysportdirect.co...shaft-overview

If you guys have any questions dont hesitate to let us know :)

Kirill
RallySportDirect.com