Need some driveline angle advice

I've spent a lot of time searching, but still can't figure out the appropriate steps to remedy a slight driveline vibration I get accellerating ~ 45 MPH and above 65. It's a 99 XJ with AW4 and 8.25 axle, OME 2" lift in front and OME 2" lift + AAL in back (which is closer to 3").

The current angles are as follows:



From what I've read, the TC and pinion angles are supposed to be equal to eliminate vibrations, but mine already are! Also, I've read that the maximum angle that a U-joint should be subjected to is 6°, so mine seem dangerously close at 5.5°. Is there a way to decrease my U-joint angles without throwing the other angles out of spec? What else can I try to get rid of the vibrations?

The pinion needs to be a degree or two less than the t-case ange to allow for the pinion twisting up slightly under load.........like accelerating up to 45 and speeds or 65. Check that out.

have you tried un-bolting the front driveshaft and see if that maybe has an effect?

XJ_ranger said:

have you tried un-bolting the front driveshaft and see if that maybe has an effect?

Click to expand...

Hmm, I don't understand. What would this tell me?

Um...if it's your front driveshaft that's causing the problem.

You check your U-joints to be sure they are good? Your current setup is the most prone setup to vibrations (97+ TC design, 8.25 rear axle, AW4 tranny) even at the smallest sized lift.

i second the unbolting of the front shaft and brand new u joints in the rear

JNickel101 said:

Um...if it's your front driveshaft that's causing the problem.

Click to expand...

Of course...duh:dunce: I've been so focused on the TC back that I wasn't even considering that the vibes could be coming from up front.