Driveline Angles

So I have a 96 XJ, AW4/NP 231... RE 3.5" lift.

I have shims out back 6* I think, they could have been 4*, and it had bad vibes at 25-30mph but otherwise was fine. NO Tcase drop.

Well, it chucked a ujoint, so rather than buying a new ujoint, I got a RE SYE hack-n-tap and haven't installed it yet.

Understanding that driveline angles of the output shaft is to be parallel with the rear axle pinion, have the shims screwed this up? Will I have to remove the shims?
-Matt

ChevelleSSLS6 said:

Understanding that driveline angles of the output shaft is to be parallel with the rear axle pinion, have the shims screwed this up? Will I have to remove the shims?
-Matt

Click to expand...

That is incorrect for a CV shaft,output shaft angle doesnt matter.The pinion should be about 1-2* lower than the drivshaft angle!

Yeah, point the pinion a degree or two below the driveshaft like RCP suggests and you'll be fine. Note that doing the hack and tap will change the driveshaft angle so mock it up and find your new driveshaft angle before ordering the shims, then put your original driveshaft back* while waiting for them in the mail because the vibes will be pretty bad with the hack-n-tap done but not the pinion angle correction.

* this is why you mock it up instead of actually cutting the slip yoke and installing, you need to put it back to OEM while the shims are in the mail!

I have the lift and shims on it right now... with that I dare say the pinion is angled up (as I was hoping to get by better without a sye) but the vibes that were not bad at speeds under 70mph but at 25-30 the vibes were horrible and of course killed the already old ujoint, so here I am with a FWD Jeep... now I know what a compass driver feels like LOL.

So a Hack-N-Tap was ordered rather than replacement u-joints. Tomorrow I'm off to get a Napa PUJ627. Wouldn't the best driveline angles be achieved by the longest driveshaft? (cutting the tcase output shaft down so there splines on the output shaft are as long as the splines on the sye (an inch or two))

I apologize for the confusion.

I have the same year, t/c, lift and all. If you already have the 4 degree shims in just leave them once you get the h&T in it will most likely work out pretty good. If they are 6 degree you may have to switch them out for smaller ones but that is too easy.

The order of my build:
1. 3.5" RE SF Lift - crazy vibes but I expected that
2. Installed 4 degree shim - pipe dream chance of helping vibes going to install tc drop but decided against it cause i did not want to take off crossmember
3. Installed SYE with front drive shaft - worked but ds was just a little too short which caused vibrating
4. Ordered Tom Woods ds - smooth as silk