by Enid_Triton on Mon Jun 03, 2019 6:11 pm
Old post, but I got this crappy vibration in my mn just recently after a 2" lift.
I worked it out by measuring the Uni-joint angles & then adding castor shims to get the pinion & rear shaft as close as i could to perfect, I also dropped the gearbox by 2.5mm so I could just get the top half of the tail shaft entering the center bearing at (what I think is ) a decent angle. Doing this was not really necessary but I'm finicky, and it does help.
But the best thing I did by far was to add a set of heavy steel drawers in the back to give the old girl a constant load.
Also, the top half of the tail shaft angle is not all that critical, although it is desirable to get it fairly level (but definitely not pointing upwards), think of it as just being an extension of the drive shaft, even if it's sloping down by 4 degrees
The Uni-joints on the bottom half of the two piece tail shaft are the ones you need to worry about and to find out what working angles they are at now you measure the angles on either side of the Uni-joints. This means for the top uni-joint you measure the angle of the top half (or the small tail shaft tube) on the other side of the bearing and then you measure the angle on the lower side of the bearing on the long tail shaft tube. Then subtract lowest angle from highest. The answer you get is the present working angle of that uni joint.
EDIT: I decided to rewrite this next part to make it simpler to understand, how I worded it before even confused me:
So, using the above as a reference lets assume that the drive angle is 4 deg down and now lets say the top half of the shaft is at 10.5 deg down we subtract 4.0 from 10.5 which gives us the working angle of 6.5 degrees. 10.5 - 4.0 = 6.5 degrees
To find the angle of the second Uni-joint we measure the angle of the top tail shaft which we already know is 10.5 degrees and we also measure the angle of the bottom half of the tail shaft, let’s say that is at 11.5 degrees. So now we subtract 10.5 from 11.5 which gives us 1.0 degrees and that is the working angle of the second Uni-joint. 11.5 - 10.5 = 1.0 degrees
Now once you have those two measurements you can work out exactly what your pinion angle needs to be set at to be correct. This may seem a little confusing for some but please preserver because although it may seem complicated, in reality it is really very easy to do.
We just need to find the difference between out first two operating angles that we just worked out.
We take our first operating angle & subtract our second operating angle from it.
Since our first operating angle is 6.5 degrees and our second angle is 1.0 degrees the math looks like this:
6.5 - 1.0 = 5.5 degrees.
So there you have it, to get a perfectly in harmony two piece tail shaft you set your pinion angle at 5.5 degrees and your vibrations will be gone.
Now, here is the formula to work out how much you need to change the present angle of your pinion-shaft from where it is sitting now to get to this magic angle of 5.5 degrees.
All you need to do to find this angle is to subtract the second tail shaft angle you worked out earlier from the angle that the tail shaft needs to be.
In this example we know the pinion angle needs to be set at 5. 5 degrees and we know that the second tail shaft angle we worked out earlier is 1.0 degree. So, you just subtract 1.0 degrees from 5.5 which gives you 4.5 degrees.,
The Math is - 5.5 - 1.0 = 4.5 degrees. This means that you need to change the present pinion angle by 4.5 degrees from where it is now using castor spaces under the leaf springs. It really is that simple, and it worked perfectly for me.
But just remember that the angles I have used above are just examples to show you how it is done, & your Triton tail shaft angles will be totally different from these and hopefully closer to being uniform than the ones I randomly picked.
Also, Please note:if you have part of your shaft that points upwards instead of down you have to work it out differently, and although it is simple to do also I will not bother with it here as it just might confuse the process. But if you need it PM me and I will give you the formula to do it. Also for those who think that the pinon angle and driveshaft angle need to be exactly the same as each other to get the shaft in phase, well, that is true on a one piece tail shaft, but even though uniformity it is desirable with every angle measurement on any tail shaft it's not critical on a two piece. Just by working out the pinion angles as we did above gets it where it needs to be.
Also rotating the center bearing may work for some people but the theory that it lowers the center bearing is nonsense.
Has anyone ever bothered to measure the height differences of the actual drive shafts with the bearing Rotated? Well I have and using the cross-member that it sits on as a base to measure from and with the center bearing rotated it actually raises the the bearing & the drive shafts by close to 6mm.
No wonder so many people get confused with this tip.
Hope this helps.
Last edited by
Enid_Triton on Wed Jun 05, 2019 7:46 am, edited 2 times in total.