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It's not the same as lightening the flywheel.  The flywheel gives the engine end of the drive train additional momentum, which assists with maintaining revs (helps you to not stall) when you let the clutch out.  This improves driveability.  There are some other benefits during gear changes. 

A lighter driveshaft (or lighter wheels) will not have this effect on driveablility, as they are on the other side of the clutch.  There is no downside - beside the cost.  :rolleyes:

I don't understand your logic. The tailshaft is a rotating piece of the drivetrain, exactly like the flywheel.

I'd argue that there is a lot more bang for buck in things with large diameter because inertia does after all have a r^2 component.

I'd pick flywheel lightening to be biggest bang for buck for reasons of weight, angular velocity range and diameter.

The rest would be hard to separate. Wheels get the vote for weight and diameter but you want the weight removed from the extremities, which may be difficult to achieve.

Tailshaft is relatively skinny so i'd think it's bang for buck is pretty low.

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the down side of a lightened flywheel is that engine revs will drop quicker when gear changing, because there is less energy to keep the momentum going

what hes saying is that the tailshaft is disconnected from the engine when the clutch is in on gear change, so you dont get this affect

the car itself may lose momentum quicker(although would probably be marginal), but the engine revs wouldnt be affected

the down side of a lightened flywheel is that engine revs will drop quicker when gear changing, because there is less energy to keep the momentum going

what hes saying is that the tailshaft is disconnected from the engine when the clutch is in on gear change, so you dont get this affect

Right on.

I agree that the flywheel will offer greater performance benefit from an inertia perspective (hence, I have one in my track car). However, you do pay for it with driveability. The driveshaft offers less bang for buck, but if I had an infinite supply of loot, I'd buy one. :)

Another benefit to a lighter flywheel is that it spins faster than the driveshaft in the gears lower than 4th. As such, it needs to accelerate faster and therefore offers further potential gains from lightening. The driveshaft spins faster than the wheels, but with 4 wheels there is a greater opportunity for weight saving.

Edited by clayoth

As you can see, they aren't actually made by Trust: http://www.trust-power.com/14import/carboneshaft.html

There was one for sale on Yahoo JP a few weeks ago (brand new I think). Unfortunately it was for an R34 (IIRC), otherwise I would have been sorely tempted.

im not a big fan of nismo i havent had the best of advice from them

Ummmmm.. are you talking about www.nismo.com.au, or Nissan Motorsport (aka. Nismo)? BIG difference.

only reason the GTR ones are $4000 is because it has GTR written on it

you know what i mean

all i want is a place that sells these shafts not snide remarks leave that for the SDU forum

I'd say it would the carbon fiber that costs the money, not those three letters.

vivid racing might be able to help. $US + Shipping, though.

face it. this is an expensive way to go faster. why not just get a shorter diff?

eh - and the snide comments are free.

why not get it directly from

http://www.acpt.com/

I think it will only cost around $AUD1500

may be someone should organise a group buy for these badboy. There are also some safety benefit with cf driveshaft. However I've never heard of gtr driveshaft breakage.

the down side of a lightened flywheel is that engine revs will drop quicker when gear changing, because there is less energy to keep the momentum going

what hes saying is that the tailshaft is disconnected from the engine when the clutch is in on gear change, so you dont get this affect

the car itself may lose momentum quicker(although would probably be marginal), but the engine revs wouldnt be affected

Engine revs change during gearchanges anyway tho, so I still can't see the downside of having a lightened flywheel.

If you are going to use this argument then you would also have to say that weight savings anywhere on the drivetrain side (or anywhere else in the car) will have a negative effect during gear changes. ie car will slow down more quickly.

Edited by browny

iwells i was talking about www.nismo.com.au

ebola thoes three letters cost in this case $3500 more for a simlar product

thanks for your help guys i will have to inquire the places in the above mentioned and see what happens if you have any other sites let me know

I see there are a few people commenting who actually don't have any experience with either a lightweight flywheel or tail shaft.

Neither the lightweight flywheel nor the tail shaft cause drivabillity issues.

Thats from experience.

Keep thinking about it. and then ask someone who builds race cars.

I have just got info back from Jame Martin the product manager at ACPT.

They have off the shelf designs for R33, R33 & R34 GTR tail shafts. The price including shipping to Australia is $2,160 Aussie dollars for just one, I am sure we can get it a tad cheaper again if we group buy.

This makes it half the price of the jap units and more than attractive enough as a modification when you consider that there aren't too many mods for $2k that are as good as the accelleration you are going to pick up from one of these bad boys.

I shouldn't go on but the mines R34 is equiped with carbon tail shaft and it is quite a big reason behind the 'response' of the car.

Here is one test of a rotational mass reduction on a V8 setup, the big thing to note is the massive reduction in time taken to achieve both maximum horsepower and torque once weight is taken out, that boys is accelleration increases. Note this is taken in 4th gear under load.

http://www.vetteweb.com/tech/0407vet_flywheel/

Group buy anyone ? :P

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