Swapping drive shaft
 

Well I just recently picked up my lovely AT 06 RX8 and I was wondering what kind of gains I would see from swapping to the manual trans one seeing how it is full carbon....I've searched and didn't see any post. And I'm not a newbie to cars I've been around the block and I'm trying to free up some rotational weight....

None.

So the carbon and steel drive shafts weight the exact same amount? I would find that very hard to believe....

Im not to sure if its true but someone told me one is longer then the other. Im still looking into it

No they are a direct swap. My concern is the weight. If we (automatics) shave weight we will obviously have more low end power. And no it won't and 10hp let alone 1hp but it will free rotational mass which ands to more wheel hp....

The only member to do a AT-MT swap said the AT shaft it was about 2-3 lbs heavier. A long dump could save you more weight.

https://www.rx8club.com/series-i-specific-performance-mods-97/mt-swap-151684/page2/ (post 31)

Yes a long dump may save me 2-3 lbs but does no one understand the concept of rotational weight. Most people stand behind light weight pulleys if I'm not mistaken. And for the most part you are saving about 20% over stock which is what 1/2 to 3/4 of a pound and people are seeing or feeling improvements. Now what if you remove 3lbs off of the drive line for the same price you pay for your lightened pulleys but with more of a gain. I don't know about you but I will take the bigger gain for the same price...

If you can pick up one cheap, I'd love to hear the results. My opinion after talking to RR (who did the swap) and mac11 (a really smart local) is that it is not worth the cost. But if you can get a cheap one and get the swap done cheap, then give it a try and let us know.

Never said they were. I meant there's no actual benefits worthy of swapping drive shafts.

removing 3 lbs from the driveshaft is similar in weight loss to what the MT's see for a lightweight flywheel...

now i'm gonna make you think and answer this for yourselves... : Does the diameter over which this mass covers make a difference? ie... a 12lb dinner plate vs a 12lb broomstick..

The better way to go would be the broom stick because the weight is closer together I would assume but I could be wrong. Isn't that way race teams and such use smaller diameter clutchs?

Found the carbon drive shaft for $200 in miaspeedshop.com, now I dont know how reliable they are but its there.

Yeah they are all over ebay if you search I don't know how reliable they are but they are like 150...good find though

Its worth a try most bolt ons out there are $300 and up.....and they dont guarantee much either maybe 3.5 hp but thats it. A lighter weight more rigid drive shaft most likely will provide no gain but you will have less of a drivetrain loss when delivering the power to the wheels...hmm im convincing myself to do this:icon_no2:

Talk about a waste of time and energy. There will be no noticable gain in WHP.

I say since noones ventured to do it. Do it and post the results.

Not sure but I think shaving 3 lbs from the dead weight behind the steering wheel would produce the same results (and be healthier to).:uhh: :)

Although that 3 lbs is not rotating... at least I hope not... :)