My lift has been installed for about 2 weeks now, and it seems things have settled just a bit because my pinion angle has changed just slightly, for the better.

My pinion angle is 6º exactly, and slipe yoke is also at 6º exactly, and my driveline is at 17º. So, that 17º offset by the 6º pinion and slip yoke angle would put my u-joints at an operating angle of 11º right?

What is the ideal operating angle for u-joints or their limit before they start causing problems? The vibration I was having has nearly disappeared, but I still get it under heavy acceleration at about 40mph.

Anybody have any ideas as to what is causing it?

-00XJCO

Did you put the shims in the between the axle and the leaf spring? just a thought. I forgot mine on my first life. I was like hmmm. wonder what these are for... three days later I found out. LOL

how did you check your pinion angle? with waht tool?

Angle finder with magnetic base

Yeah I knew what they were for when I ordered them, notice I said pinion and slip yoke angles match, thanks to the shims

i have a question when you use a sye and spring shims do you still need to use a x-member drop shim? curious cuz when i get home i will be installing a sye. plus i have a jks x-member that will raise the t-case about a half inch. what degree shim do you need for a 4.5" lift? thanks

If you install the SYE with a double cardan driveshaft you'll have to shim the pinion up to be at the same angle as the driveshaft, won't need a t-case drop either then. I used 2º shims on mine and that worked perfectly.

if you tail shaft is at 6deg your pinion should be at 4deg
to allow for axle wrap on acceleration

That must be why it only vibrates under heavy load... Thank you!