What Tailshaft Are You Running

[Marko R1]

The gtr runs a 2 piece drive shaft, what is the subject matter here, gtst? Do they run a 1 piece shaft?

[The Dan]

Aluminum alloy has a fatigue life though... Not like steel.

I'm fairly sure steel has a fatigue life. Albeit probably less than aluminium alloy but it would still have some type of fatigue life

[The Dan]

The real problem here is that no one has called Nissan to inform them of their design flaw.

They clearly over spent on the much more expensive 2 piece design when they could have saved all that money making 1 piece shafts.

Forget engineering rules. This is obviously an oversight on their behalf. Someone should notify them

[WMDC35]

I asked these questions when it was made!

I picked up a 2 piece yesterday, gutting thing is I’ll need a second driveshaft loop and it certified!

I’m not keen on a high speed moment with the tailshaft doing some dub step death vibration

I’ll get onto Nissan and tell them to stop wasting time and money on the tailshaft and put it into forging the engine

[The Dan]

I asked these questions when it was made!

I picked up a 2 piece yesterday, gutting thing is I’ll need a second driveshaft loop and it certified!

I’m not keen on a high speed moment with the tailshaft doing some dub step death vibration

I’ll get onto Nissan and tell them to stop wasting time and money on the tailshaft and put it into forging the engine

If you aren't having a problem with the shaft you have, why change it?

You will feel a vibration before anything worse happens.

It also depends on the material it's made from and how it was made (which is explained in detail in this thread).

If your shaft maker has made it from the correct material for the length and diameter then it might be perfectly fine

[WMDC35]

they're going to check some calculations next week, will see how it goes

[GTSBoy]

Remember that the critical speed is tailshaft speed, which you will only reach when you have very high road speed. 6000+ rpm at the tailshaft is fairly hiking, and is not going to happen on the road very often, and not happen on many racetracks for long either. That said, on a racecar, that will do that speed maybe once or twice every lap....you'll eventually have a bad moment, and that bad moment will upwards of 200km/hm, which you won't like. So, not a risk worth taking on a race car, and strangely enough, probably perfectly fine on a road car.

That said, I like the 2 piece design. Engineering wise it is much smarter, and does a better job of separating any movement of gearbag relative to diff from each other - not that it matters so much in an IRS car.

But for my overall preference, the only engineers who have ever really showed an interest in doing it properly are those from Peugot and Porsche (and a few others) who used a torque tube. I can remember reading that the solid driveshaft up the centre of the torque tube on a 928 was capable of absorbing something like 7 or 11 complete twists as it loaded up on launch with a 500+ HP engine in a race car. That is some serious business.

[bigmikespec]

Steel does not have a fatigue life, it has a fatigue limit and as long as it is operated at a stress level below this then it should last for an unlimited no. of cycles.

[The Dan]

Remember that the critical speed is tailshaft speed, which you will only reach when you have very high road speed. 6000+ rpm at the tailshaft is fairly hiking, and is not going to happen on the road very often, and not happen on many racetracks for long either. That said, on a racecar, that will do that speed maybe once or twice every lap....you'll eventually have a bad moment, and that bad moment will upwards of 200km/hm, which you won't like. So, not a risk worth taking on a race car, and strangely enough, probably perfectly fine on a road car.

That said, I like the 2 piece design. Engineering wise it is much smarter, and does a better job of separating any movement of gearbag relative to diff from each other - not that it matters so much in an IRS car.

But for my overall preference, the only engineers who have ever really showed an interest in doing it properly are those from Peugot and Porsche (and a few others) who used a torque tube. I can remember reading that the solid driveshaft up the centre of the torque tube on a 928 was capable of absorbing something like 7 or 11 complete twists as it loaded up on launch with a 500+ HP engine in a race car. That is some serious business.

6000 tail shaft rpm is the same as 6000 crankshaft rpm in 4th gear.

That's 111km/hr I'm pretty sure.

[WMDC35]

i think 4th at 6000 is around 165 ish km/h (with 4.3 diff)

[GTSBoy]

Yuh, car hits 180 speed limiter at almost the same as rev limiter when in 4th.

Granted I was thinking about running the car out in 5th and forgetting that the tailshaft speed would be 25-30% faster than engine speed.

[The Dan]

i think 4th at 6000 is around 165 ish km/h (with 4.3 diff)

Yeah my bad. I'm using an imperial calculator and that's MPH not KM/H.

So with a 4.11:1 it's 178km/h at 6000rpm on a 235/45/17 and 170km/h on a 4.3:1

[The Dan]

With 5th ratio being 0.752:1 that's 148.5km/h

[GTSBoy]

No, 5th doesn't change the road speed it happens at, just the revs. You just made the same mistake I did, in reverse.

[The Dan]

No, 5th doesn't change the road speed it happens at, just the revs. You just made the same mistake I did, in reverse.

Lol. I seriously need sleep. Powercruise has f**ked me.

Let's just say.....fast

[a20089]

So I what fixed the problem cejay?

[abr33]

Got my tailshaft today, I opted for the biggest unis I could get, they built the entire shaft using my old centre plates, and my sliding spline drive. Made everything else, heavier tube, 90x30 uni's that are solid, no grease galleries. The bloke at hardie spicer said it'll handle 1000 odd hp, and massive tourque, so I should never break this one!

I did have to flare the end of gearbox cover/shield to allow the uni to clear.

Best bit, replacable uni's!!!!

If anyone wants better photos of details etc just ask..

[The Dan]

Got my tailshaft today, I opted for the biggest unis I could get, they built the entire shaft using my old centre plates, and my sliding spline drive. Made everything else, heavier tube, 90x30 uni's that are solid, no grease galleries. The bloke at hardie spicer said it'll handle 1000 odd hp, and massive tourque, so I should never break this one!

I did have to flare the end of gearbox cover/shield to allow the uni to clear.

Best bit, replacable uni's!!!!

If anyone wants better photos of details etc just ask..

That shield can be knocked out quite easily if you have trouble with it fouling. It's a dust guard for the rear seal so can be ditched with only minor ramifications.

[abr33]

That shield can be knocked out quite easily if you have trouble with it fouling. It's a dust guard for the rear seal so can be ditched with only minor ramifications.

Yeah I popped it out to flare it a little, id like to keep it on, but if it gets in the way still, ill machine up a s/s one the right size

[kitto]

This is what happens to a single piece tailshaft at 8,300RPM. Its in an AE86 so the tailshaft isn't exactly all that long either. Guy had a tailshaft loop as well, it ripped it clean out, took half the gearbox out with it along with the shifter and the fuel lines. Punched 4x big holes in the floor.

There is another guy here in SA that had a Cefiro. Freshly built car, new very expensive engine, clutch, gearbox etc etc.

Tailshaft failed in 4th gear when he attempted his scando into turn one at Mallala. The shock was so severe to the car that it the car actually buckled, destroyed the gearbox and engine. Car was pretty much gone because of a failed tailshaft.

I for one, will not be putting my single piece shaft back in.