JJeepII

[Rammin97]

Picked up this Jeep last week. Its in really good shape other than a few minor things that need to be addressed. My Daughter and I have been working on her 95, JJeep, but this one came along and I couldn't resist. Its a four door, Green like my 2 door, 4.56s ARB up front and Auburn LS in back. 4.5 RE shortarm with discos, extended brake lines, and good tires.

It has a driveline vibe at freeway speeds that is bugging me so i want that fixed before handing it over to Jorji to DD it. Not sure if its the angle of the rear shaft or maybe its out of balance? Is there anything else I should look at? Thanks in advance :sunshine:

 

[blondejoncherokee]

first swap front tires to back, and back to front , to see if it helps.
check for a bent rim. possibly take tires in to get balanced to rule out tires, unless you're sure. or just swap over a set of tires that are known to be balanced , if vibes go away , you know its tires, if they stay , you know its something else.


second pull front driveshaft and then drive it on the freeway.
see if that helps. check front driveshaft pinion u joint for wear and inspect the CV joint and U joints at the CV as well.

if that doesn't do it, then

third pull rear DS and check for pinion u joint wear, and check U joint at the slip yoke.
West sac driveline will usually balance a shaft for 60$, and u joints are 15$ each.
then measure pinion angle, and Tcase output shaft angle to make sure they are the same (if stock) otherwise make sure the pinion angle is the same as the DS angle, or 1-3* below, if its an SYE.

also check motor mounts and tranny mount for wear as well while you're at it.




does it have an SYE? or is the stock slip yoke setup?

 

[Rammin97]

Thanks John!! It does have an SYE and CV shaft. I haven't taken a close look at it yet to see if its aftermarket or an XJ/ZJ front shaft. It has a bigger tube than the front so I am not sure where it came from.

 

[blondejoncherokee]

make sure the rear pinion angle is 0-3* below the DS angle. since you have a SYE, you can actually take turns pulling front shaft then drive it. then re install front, then pull rear, then drive it. try to isolate the issue from front or rear. if it happens all the time, then maybe tires. with only one shaft, start with the shaft and replace u joints or CV if needed.

 

[BlueRockRash]

blondejon is the man

 

[Rammin97]

Yes he is!!!

 

[DaveNJeep]

If that's a hack and tap I think I installed it! haha. I can't remember what DS he used though (it's been a few years!). I would start at the tires, as much as I love BFG they are nortorius for balancing issues.

Jon has some good thoughts although I've heard if you have a DC joint with a SYE you can set the pinion at 1 degree below the DS angle. That's the way I have mine set up and I have no vibs.

I'm so glad this XJ stayed in the club. I look forward to seeing you at SF! Or before!

 

[blondejoncherokee]

i usually set the DS 1-3* below the pinion angle for an SYE to account for axle wrap.

 

[blondejoncherokee]

i usually set the DS 1-3* below the pinion angle for an SYE to account for axle wrap.

if you still have vibes after all of the things listed, i would start considering the t case,
but bad DS angles, bad u joints, out of balance tires, bad CV joints, out of balance DS, and more can all cause driveline vibes. i would not be surprised if it was a way out of balance tire.