FS 1 piece driveshaft (feeler)

I am 99% sure my problem is axle wrap related. I only have a vibe under load. I can cruise at any speed and its perfectly smooth.

The truck is 1000 x smoother than it was with the 2 piece

I have Alcans, which are really flexy, and the truck makes a good amount of power, so I bet the pinion stands right up.

I also compared the clearance. it hanges maybe 1-2 inches lower, max, and the difference is most where the carrier was, I dont think its that big of a difference to tell you the truth since you are high centered as hell at that point anyway.

Also, my DS has a CV at the t case, from the research that I have done, your pinion and T-case are supposed to be parallel with a u-joint up top, and the pinion should be parallel to the DS ( Shimmed) with a CV upper joint.

And the slip joke location doesnt matter really. The first gen trucks has the yoke at the Diff, and the 2nd gen trucks have it at the carrier stock. My DS was made from my stocker, and I had them put the CV in it, hence the slip yoke had to go at the diff.

Justin

 

read this a couple times, hard to get at first but it eventually clicks




The single-cardan style driveshaft, also called a "standard" driveshaft, consists of a tubular shaft with 2 tube yokes, one at each end, that each utilize a single cardan u-joint. Recall how, when we have a single u-joint operating at an angle (as will certainly be the case in any 4x4 because the transfer case output will be above the pinion) it causes the driveshaft to speed up twice and slow down twice each revolution. Uncorrected, this change in angular velocity will cause annoying vibration, wear out u-joints, and cause undue stress and strain on the driveshaft itself, transfer case output, and axle pinion.


The solution is simple and elegant. If we ensure that the u-joints at each end of the shaft are both "in phase" and operating through exactly the same angle, the pinion end of the driveshaft will speed-up and slow down opposite to the transfer case end, and therefore the different angular velocities cancel one another out, the pinion is driven at a steady rate, and vibration is minimal (if I did a decent job of describing why the elliptical paths happen in the first place - you should be able to prove this to yourself). This works fairly well up to angles approaching the maximum operating angles of the u-joints in question. As the angles grow, so do the magnitude of the accelerations and decelerations, and the less effective the matched angle are at eliminating vibration.



In other words, eventually, you may have a driveshaft operating at such an angle that, even though the input (transfer case) and output (pinion) operating angles match exactly, the shaft will still vibrate. At this point, it's time for a double cardan CV driveshaft!




Note that in the standard single-cardan shaft "match the angles" geometry the angles do not have to be the same "sign". THIS IS A COMMON MISCONCEPTION. Certainly, the most common method of achieving proper single-cardan shaft geometry is to set the transfer case output and pinion shaft centerlines parallel, thus achieving equal angles between each end of the driveshaft (pic at left).



Normally, this is done by rotating the axle housing (with shims in a leaf-spring suspension, or with relative lengths of upper and lower control arms with a link suspension). This is because the transfer case output is usually considered pretty fixed - the only way to adjust it is to either lower the transfer case (an all around bad idea and bad deal - I speak from experience) or to tilt the engine up (raise the engine mounts) again - not a good idea).




However - this is not the only acceptable method of achieving the proper matched-angle geometry. The angle between the driveshaft and pinion can be opposite to the angle between the transfer case and driveshaft - as long as they are equal. Note that they must still be in phase. This unusual configuration is called "Broken back" or "W" geometry (see pic at left ), and is common on agricultural equipment, marine drives, some tractor-trailers that use stub-shafts between front and rear of a tandem assembly, and most often on power-takeoffs like hydraulic pumps and PTO shafts.



Most of the equipment that uses driven shafts in a broken-back configuration though, are fairly low RPM (but not all). The reason is, due to the nature (geometry) of the configuration (again, have a look at the picture above) with this setup, there's a lot more inherent strain on the slip member as it rotates. because of the opposite angles, the shaft "wobbles" the slip member back and forth as it rotates - like a skipping rope being swung. At high rpm, with anything but the tightest slip-joint assembly, this would cause a horrible vibration - that's why Spicer light duty driveshafts do not normally come factory in this arrangement. Note however, that some Land Rovers do have stock driveshafts in the broken back configuration, so it can work! I don't have any experience with these Rover's, but I imagine that the angles in the stock configuration are pretty darned small. As with the more standard single-cardan setup - start increasing the operating angles of the u-joints and the elliptical paths get more and more elliptical, the angular velocities (amount the shaft speeds up and slows down each revolution) get greater, and when you spin that shaft at 1000rpm, the more likely it is that the shaft will be noisy, harsh, and vibrate - EVEN IF the angles are matched. Again...time for the double cardan CV shaft!