1 Piece Drive shaft. Bad vibration after install

[efwojcik1]

Bought an aftermarket, aluminum one-piece driveshaft from conceptzperformance.com which sells inland empire driveshafts. First one came, installed and had a nasty vibration from 60mph and got worse the faster you go. Took it out and it was a lil to short and i wanted a 3.5" driveshaft instead of the 3". So i sent it back, and got the new one yesterday. Now mind you I reinstalled the OEM one before and the vibration disappeared. I could take the car up to 160mph and the vibration was not there. Took the OEM one back out AGAIN and installed the new, proper length 3.5" driveshaft, and what do you know, THE f*** STILL VIBRATES! But now it vibrates from 80mph+ and gets worse as you go faster.
Now I know the length is right, the OD is proper. From where I am sitting there are only 2 possibilities here.

1. I need to try clocking the driveshaft to a different position to see if this helps it. probably 90 degree and if that doesnt work, 180 degree. Now, on the driveshaft at 12'oclock and 6'oclock there are flat machined recesses in the yoke. I am assuming this will ONLY allow the yoke to slip into the transmission, over the output shaft if these are orientated right, so it is not possible to have it 90 degrees out at the transmission end. looking at pictures online I see that the flange is machined a certain way and maybe i have it bolted up 90 degrees out from where it should be.

2. The drive shaft is out of balance or they did not balance it to a high enough RPM. Like i said, i take this thing to high speeds. The car is tracked and needs to be PERFECT, so no vibration is acceptable.

Before the obvious q's come in, heres what is up. Its and RB25 motor mated to the 300zx bell housing with rb25 internals. I replaced the transmission mount with a Nismo one after i had the vibration the first time. The differential bearings are fresh, less than 5k on them. The wheel bearings are tight. The tires are nice, and I don't think there out of balance, besides the car was smooth with the OEM driveshaft and didnt pick up this vibration until i tried using a 1 piece shaft.

[BigTDogg (MA)]

I'd try clocking it first and see if that helps. Luckily it's a relatively easy part to swap out. Hopefully Coz will make it right.

[efwojcik1]

Coz is a good guy. Its not really anything he can do tho, he didnt make it. I have been talking directly to Jeff at Inland Empire to try and sort this out. I spoke with him again and he agrees it must be something drivetrain related since the OEM driveshaft worked fine without any vibrations.
I am going to try clocking it tonight to different positions and see if it helps. If the vibration does not disappear, Jeff said to send it back to them again and he will make me another one with different yokes and see if that fixes it. Pretty irritated at this point but im really hoping its something i did and can just reinstall the driveshaft. If it ends up being that the yokes were messed up from the beginning or the shaft is out of balance, im going to be a lil angry here. The first one being messed up, ok it happens. If the second one ends up being wrong then im just going to assume that either they are not balancing there driveshafts properly or the yokes they gave me are garbage.

[AussieAdam]

So what happened here ? did clocking it solve the problem, I am having a similar problem with a Shaftmaster one piece - I have one like yours as a second test unit as well which I have not fit yet.

My factory two piece did not vibrate at high speeds but it did at around 60 - 80KM/h - since putting in the one piece it vibrates / resonance around 90 -100KM/h but the vibration at 60km/h - 80km/h has gone !

I have clocked it @ 180' no real change - I am yet to try a 90' position either way. - if that all fails I will try the second tail shaft.

clocking does make a difference, well it did with my two piece - after having the center bearing replaced by a specialist in hope to remove the vibration @ 60KM/h I had a resonance @ 100km/h ( smaller than I have with the one piece now ) I clocked it @ 180' and problem was gone.

I was so please after fitting the one piece.... drove up to 80km/h think YES IT FIXED .... then hit the highway - got up over 90km/h .... OH NO ! - hearing how your turned out would be good - THANKS

[Ikon_1911]

What was the results? I know it's a few years later !! Interested in getting a one piece for my NA 2+2 auto...

[rayop]

I am thinking of doing the same. Results?

[centralcoaster33]

Hey guys, welcome to NICO Club! You can see the date of the posts in the upper left corner of each post. If you look there, you'll see this thread was created and only active in 2012. Ikon resurrected this thread in 2016 and never heard back. Odds are that the same thing is gonna happen Rayop, no response to anticipate. Don't give up though. Try some other threads for research or try some more current threads if you want conversation. Consider making your own thread. Ooh, and consider using shaftmasters if you're wanting to buy a one piece shaft. You might get a NICO Club discount if you ask nicely. Finally, this thread has nothing to do with that, it has to do with an out of balance driveshaft from conceptzperformance/ empire driveshafts, two driveshafts actually.