ok thanks Ed, I've been doing a bit of internet research & most of the opinions out there are against multiple cardans,i think I will just stick to a double at the yoke end & a single at the diff.
Yea. It finally started coming back to me on the way home last night.
There are three different configurations for drive shafts. Two u-joints - one on each end, Cardan and u-joint - one on each end, and a Cardan on each end.
Level of potential for vibration/vibration follows that order with the first being the least likely and the last being the most likely. If at all possible, you ALWAYS want to use the first, followed by the second if the 2 u-joint setup won't work, followed by the last if NOTHING else works.
And, never use a double-Cardan joint setup for high-speed highway use. Such as in a NP242 AWD setup.
As explained to me, the u-joint and drive shaft stabilize the Cardan joint. That's what makes this setup work on the highway at high RPM. Its like having a rotating solid shaft attached to the end of the Cardan joint. It minimizes potential vibration through the pinion/u-joint/drive shaft and stabilizes the Cardan joint.
I still think my custom shaft I had made here is a dud, the double cardan seems a bit stiff to me & it has too much run out for my liking.
Hmmm. Don't know there. I think all your worrying about run-out is for nothing. The tech that works on my Sports at the dealership built his drive shafts at home for his Truggy. He swears he can run it at 60 down the highway and there's not a hit of vibration. I'm pretty sure the 'run-out' on his shafts isn't down to specs you were quoting.
If it were me, I'd bite the bullet and align the front diff correctly. If I put that much work into something and then had to live with an unnecessary vibration, I'd go nuts.
Edward
