Project GT-R: Lightening The Driveline
Thinking About Rotational Mass

Tuning is not only about upping power and shooting for greater performance, it’s about refinement too.

One of the nicest upgrades I’ve ever made to Project GT-R was replacing the slipping stock clutch with something more durable. At the time, ATS had been on the market for a couple of years with its carbon single and multi-plate clutches, and after developing and refining them, it launched a more street-oriented application. Aside from weighing a lot less than comparable performance clutches, these ATS carbon clutches also had the added benefit of a much more natural feeling of slip on engagement, rather than the snap you get with metal plate equivalents. This totally changed the nature of the car; the RB26 felt more rev happy, and the car was a joy to use even in terrible Japanese traffic jams.


Since then I’ve been wanting to refine the driveline further, the obvious next step up from a carbon clutch and lightened flywheel being the propellor shaft (driveshaft). Seeing the R35 GT-R come with a carbon fiber component from the factory only made me crave one more, the need to modernise and perfect every aspect of Project GT-R becoming stronger than ever. It was always something I assumed I was going to do when the rest of the car was ‘completed’ (if ever that happens with a project like this!), so it was put on the back burner.

That was until earlier this year when I got in contact with the guys at The Drive Shaft Shop in North Carolina, following a discussion at Tatsumi PA with a fellow GT-R owner which reignited my interest. They were keen to come on board, and in no time had sent me out one of their lightweight carbon prop-shafts.


It’s always nice receiving boxed-up goodies for your car, and this time around there was no hiding what the long package contained! Like many things that I stock up for Project GT-R, the box ended up sitting in the office for a few months, but the time finally came to fit it up when I dropped the car to Ito-san at Do-Luck for a bunch of work the week prior to R’s Meeting.


So while Ito-san and his mechanic were busy routing water lines for the new turbo install, I unboxed the carbon shaft and took a closer look at it.

It’s easy to see that this shaft is built tough. Despite being considerably lighter than the factory two-piece item, it’s rated up to 1200hp, which should do me just fine and dandy. At the rear differential end there’s a custom modified High Speed 108mm CV in which the 300M spline slots into.


The other end of the prop-shaft has a flange that bolts right up to the transmission. Each and every shaft from The Drive Shaft Shop is balanced to ensure there are no nasty vibrations or harmonics, and you can see the one sent over to me had couple of metal weights glued in place for this very reason.

The Weight Comparison

After dropping the stock two-piece driveshaft out of Project GT-R, a direct comparison was needed. Lining them up alongside each other, the simplicity of the single piece, carbon constructed shaft became obvious.


Luckily, Ito-san had a digital scale handy, so I stood The Drive Shaft Shop shaft on it, revealing of weight of just 7.6kg (16.7lb).


Doing the same with the two-piece stock item proved a little trickier, so I pulled Ennio away from his ECU prepping duties and had him balance it on top of the scale.


The result this time was 13.2kg (29.1lb). This makes the carbon one 5.6kg (12.3lb) lighter, which is quite a drop in mass off the driveline.

Adapting & Fitting

After the first test fit, Ito-san realised that there were a couple of issues. First up, the whole assembly seemed to be a couple of millimeters too short, which meant he had to make use of the longitudinal play in the CV/spline and pull it to get it to fit properly. That wasn’t going to be too much of an issue, but upon checking again it turned out the CV joint itself was a few millimetres too big, and wouldn’t fit into the receiving end of the diff mount. Ito-san said this happens at times and tried to sand it down a little.


That didn’t remove as much as was required, so Ito’s mechanic, who’s quite handy with a belt sander, took off just what was needed.


A second quick test fit and all was fine so the bolts were added and everything was tightened up.

So what is the effect of an upgrade like this? Well, as you can imagine, 5kg removed from the rotational mass can be felt instantly. When driving the car around, the driveline reacts much faster when you get on the throttle so the response is greatly improved. There is no more hanger bearing there to sap such feel from the driveline as there was previously with the stock item. But the most pleasing thing is zero harshness or driveline shunt when accelerating and backing off the throttle, like in stop and go traffic. It all runs smooth and I’m more than pleased with it.

With the car running on stock injectors and not quite finished yet I could only push it so much, so I will have to explore this further the next time I have the chance to drive Project GT-R hard. It is, however, one nice small step towards a more modern and higher performing BNR34 GT-R.

Dino Dalle Carbonare
Instagram: speedhunters_dino



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Very nice upgrade. I'm guessing this company makes a similar unit for R32-33's?


Hey Dino, long time follower of yours and loving the updates (was so quiet for so long!)
I have a I've got a 34 v-spec as well and was considering this myself however i was advised that this modification can put extra strain on the diff and transfer case (without the flex provided by the two piece item)
Have you heard about this and if so, will it put extra strain on, or cause undue wear to, the aforementioned diff and case?
Looking forward to seeing more!


Ares180BPM yeah it will all make sense once I finish up the engine. It's all worth the wait! I guess I'll find out about the extra strain/wear but in all honesty I do not feel any slack or jerkiness even at low speed on/off throttle applications

Gianluca FairladyZ

funny that nissan installed carbon drive shafts originaly on the Z33 but not the GTR's .... ???


If the flange doesnt fit, get another part
Sanding it down will make it sit out of balance


speedhunters_dino Ares180BPM From what I understand, the carbon shafts actually take stress off of the tcase and diff.  If you had a one piece steel driveshaft, extra stress would be a concern as well as critical speed rating (which is twist on the shaft from torque that could cause it to break in the center); but the carbon actually has some twist to it and sort of slingshots to prevent sudden jerks on the driveline.  It's a similar effect to a drag slick wrinkling.  The strength carbon has over steel is significant enough that you can use a longer carbon shaft without worrying about critical speed rating as well.  There's really no downside to a DSS carbon shaft, especially if your stock shaft has non-serviceable u-joints.  The spicer replacements for the DSS shafts are off the shelf items.  I love my DSS carbon driveshaft!  (Sorry about the grubby clothes, just came in from the garage haha!)


"5kg removed from the rotational mass can be felt instantly."
The placebo effect is strong in this one.

Cool build though.


Lmao yup.


DerpyToast  Disagree with you here, friend. (Very science-y explanation coming) Acceleration eats energy, your engine and driveline are accelerated a lot quicker than other parts of your car. Thus
the most effective place to reduce the polar Moment Of Inertia is on the
parts with
the highest angular acceleration. This is why reduced mass
flywheels, driveshafts, etc work so well. The effective mechanical
impedance of any part goes up
with the square of the angular velocities. The first gear of an R34 is
3.83:1 so its 14.7 times more effective to pull mass from the the
rotating assemblies/driveline to
increase your angular acceleration. The simple fact of the matter is; for a given torque, lighter rotating parts will have a greater angular acceleration. No placebo, the change will be immediate.


Trentworth DerpyToast

A change of mass so close to the central axis is trivial, if this removed from the outside of a flywheel, well way from the centre of axis, then acceleration would improve.  Also, first gear or fifth gear makes no difference, the prop-shaft rotates and road speed not engine speed.  However, the massive placebo of a classic Play Station Grand Turismo upgrade always helps?  Loving it Dino, keep the updates comming.


malmoy Trentworth DerpyToast
What he said.

Small weight savings add up, but each individual change wont be noticeable on its own.
Butt dyno's are never right because humans are terrible and making non-biased comparisons.
It's a cool upgrade and build none the less.

Trent's "science" is troll level wrong to boot.


With my BCNR33's carrier bearing needing a replacement, I may just go all out and order up one of these over winter. My wallet thanks you Dino! Hopefully the Getrag conversion doesn't cause their off the shelf unit to not fit. I guess i'll have to wait until Aki's Project R33 goes this route and follow suit! Great write-up!


I just gott a nice six-month old GMC Acadia SUV by working part-time off of a macbook air


Very interesting upgrade. Nice write up!


Non carbon shaft are just sad and pathetic.


You can remove much less that 5.6 kg weight from the flywheel and feel the improved acceleration.


DeWeberis I've done that already :D


@turbo BEAMS ae86 What have steel shafts ever done to you, poor things lol


Jaemcius Thx


Kunal Arneja Ask Aki lol




DerpyToast malmoy Trentworth Think what you will, but it's definitely very perceivable. Plus saves my fat ass having to lose 5 kg so it's a win win on all counts hi hi hi hi ;)


Gianluca FairladyZ #becausenissan


AlchEm1st speedhunters_dino Ares180BPM That is a big shaft. hahaha


fabulous71 Yes they do


If only there was a way to share or measure the difference in feeling, because I really wonder how it feels.

No matter how big the difference might be, there's no denying the carbon shaft is just such a nice "thing".


I'm right down the road from Driveshaft Shop, but I'd rather have a CTG/Torqline unit if I had that car.  Don't know if they still make them for that car, and they're probably at least 50% more than that Driveshop Shop piece, but very nice...


reistje You can measure the torque response curve between the transmission and differential, and you can measure (or calculate) moment of inertia, both of which are different between a carbon shaft and a steel multi-piece shaft.  

How you communicate that difference between people is another story...




speedhunters_dino AlchEm1st Ares180BPM Yep!  That's why I ended up going with carbon.  I had planned to do a steel shaft; but DSS said that with the length I needed there would be critical speed rating issues and I would need to go with a two piece shaft.  They did some math and came back to me with news that it would be only a little more expensive to do a carbon one piece shaft.  As I didn't really want to fabricate a hanger for a two piece shaft, that's what I went with.  It's for a one off custom build I did with my Dad in my parents garage.  As far as I know it's the only complete Evo IV Coupe in the U.S.  (I know most of the guys who have done Mirage conversions stateside)  Done via an extensive floorpan and framerail restoration and swap into a Mirage Coupe chassis.   Still a work in progress, but it's very close to being done.  It has a fully built 2.3L stroker engine I assembled myself.  Shooting for a 10 second car with little to no lag for track days and autocross.  When it's done next year I'm gonna hit you guys up for a feature haha!


Great to see continuing updates on Project R34! This and Project R33 are my favorites, even if they feel like teasers at times. Keep up the good work!


AlchEm1st There are a few Evo IV rally cars in the US, not conversions.  They're not street legal though as they don't have production VINs and were only built for racing.


@Fabrik8 AlchEm1st Yep, that's true; but mine is the only IV Coupe.  They never made an Evo Coupe.  There's only a few (two that I know of) 5th gen Evo Coupes in the U.S. that are full conversions.


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People need to forget about CTG - they will not be making any more carbon driveshafts. DSS all the way!


How much does your flywheel and clutch setup weigh? On Bambi R33 GTR we had a 9.1kg flywheel and clutch setup along with a DSS carbon prop. Acceleration and response from. 600bhp/520ft/lb engine setup was just ballistic. Good luck Dino!


It's normally the plate that fits over the cv end. Mine was too big so they sent replacements.


DerpyToast malmoy Trentworth  Dude, I've been called many things on internet discussions over the years, but this is the first time I've been a troll. I'll remind you that speedhunters_dino shaved ~42% of the weight of his driveshaft off with a single mod, according to you
and the evidence you have to back your assertions up I may be wrong,
but I hold that the simple act of cutting 5.6kg off a part that requires
energy to accelerate then decelerate multiple times over a single drive
will be noticeable simply because it will take less energy to drive
this entire process. And as far as it being a 'classic Gran Turismo mod'
I wouldn't know about that as my parents took away my Playstation when I
was 10 so I didn't get to play these games until I was old enough to
buy my own platforms at which point I wasn't really interested anymore.


Trentworth DerpyToast malmoy speedhunters_dino Grab a big golf club or broom, hold it straight out in front of you by the handle and try to quickly raise it up.  Now hold the club or broom by the heavy end with the handle hanging down and try to raise you hand quickly.  It weights the same but it is harder to accelerate the heavy end when it is out in front of you up (and around) than it is to accelerate the same weight close to you.  The prop-shaft has a very small diameter (compared to a flywheel) so it is close to holding the golf club by the heavy end and not having to rotate a heavy mass around a big circle.  5kg is 5kg but I doubt, as the diameter of a prop is so small, that it makes much difference.  Anyhow, I can't afford these lovely things, and don't want to stop or discourage Dino doing gorgeous things I can't do so lets end this here and I can get back to beating the kids on Grand Tourismo. :)


my Aunty Elizabeth just got a fantastic green Nissan NV200 Minivan


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turbo BEAMS ae86

Gianluca FairladyZ Wdf?  Thats villanous

turbo BEAMS ae86

AlchEm1st bien Alchemix


malmoy It is a relatively small diameter shaft (3.5 inch or something like that for the DSS piece I believe), but most of the mass is in either the far outside diameter or at the joint assemblies.  It's not like a solid shaft, as a lot of the weight is at the outer diameter of the shaft and not in the center, and that's a very important distinction for changes in moment of inertia.  If you're migrating from a multipiece shaft to a single piece shaft, some of the weight reduction comes from eliminating the center joints, and the change of moment of inertia per pound of mass reduction won't be the as great as the change from removing mass from the shaft tube.

Still though, a 42% mass reduction is going to equate to a pretty significant reduction in rotational inertia for a tubular part of that type.  Again, not a solid shaft, and not the same moment of inertia as a solid shaft.  Think of it as making a small diameter flywheel that is a ring, not a disc. Completely different moment of inertia for the same amount of mass.

If you're already starting with a lightweight flywheel and lightweight wheels, reducing driveshaft inertia is obviously a greater percentage change of total drivetrain inertia than if you were starting with heavy stock wheels and a heavy stock flywheel.  Whether that means a big enough change in inertia to be noticeable is a different matter.  In low gear, when the available torque is high and the shaft acceleration is high, it could be a noticeable difference in response for many cars.  If it is noticeable on that particular car, it will be less noticeable in each higher gear as the available torque is lower and the rate of shaft acceleration is lower as well.

Go and play Gran Turismo if you want, but don't tell someone they don't know what they're talking about and then use brooms and golf clubs to explain your position.


Gianluca FairladyZ Z33 is a newer car.


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@ihateyoutoo Very nice of you.


AlchEm1st speedhunters_dino Ares180BPM Yes please do hit us up! That sounds rather interesting!


@ihateyoutoo Funny :)


Cool stuff...Eventually, did you paid for it or not? How much was it?


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Nice Dino. I always wanted to see the comparison of those CF Driveshafts. Excellent


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