TJ Driveline Issues

[burrellsjeep]

Helping a buddy figure out an issue with some vibs hes getting on his TJ.

Specs,

2000 TJ 4.0, 4 inch lift, Has transfer Drop, No SYE

Here is the issue it only has the vib well in the gas, Let off and its smooth. Does this at any speed. It not just a vib, Its like the death wobble of the rear end, kind of a jumpin type wobble, Feel like the rear end is wrapin up.

Checked the U joints, They all seem to be tight, The Pinion seems fine, no odd play in it (Check it on Jack stands with it in N)

Now here is what I think it is, Let me know if you guys agree or not. This is an Issue that has started and didn't happin after the lift or anything like that. So it points to a wear issue. So I don't believe its in the drive shaft or pinion it self.

My thinking is its the mounts for the motor and the transfer, I can move the transfer about an inch left or right with little effort. So I am thinkin under load its binding up the drive line causing the vibration or shaking.

What do yall think?

[Dookey]

Have someone sit in the drivers seat and set the ebrake. Shift from drive to reverse putting pressure on the drive line. Watch the pinion for excessive roll. It will show you exactly what is going on. The transmission mount is cheap. Replace it.

[burrellsjeep]

Originally Posted by Dookey

Have someone sit in the drivers seat and set the ebrake. Shift from drive to reverse putting pressure on the drive line. Watch the pinion for excessive roll. It will show you exactly what is going on. The transmission mount is cheap. Replace it.

Thanks, This was my next step.

And yeah I told him to go ahead and get the Trans mount.

[PlimothColonyJeeper]

I would not assume that the t-case drop supplied with a lift kit is actually going to give you the right pinion angle. I had trouble with a 2.5" lift even though I was running a drop. And most sources I've seen recomend a cv driveshaft for any lift over 3"

[burrellsjeep]

Originally Posted by PlimothColonyJeeper

I would not assume that the t-case drop supplied with a lift kit is actually going to give you the right pinion angle. I had trouble with a 2.5" lift even though I was running a drop. And most sources I've seen recomend a cv driveshaft for any lift over 3"

The lift/Drive shaft combo has been ran for over a year with no vibs, Seeing how it just started, Its gotta be a wear issue, Instead of a Pinion angle issue.

I see what your getting at and it is possible, I looked at tonight and the transfer has some slop side to side (Whole case moves with the driveline), maybe a half inch give or take.

I had him put the Jeep in gear and pull forward with the brake on and the pinion rotates quite a bit. He just got adjustable uppers so he putting them on tomorrow and see it that makes a difference. It is possible the UCA bushing are shot there the factory ones still. At least now we will be able to set the pinion angle.

[onetoncv]

these rigs are touchy -you need an sye and proper pinion angle to match with a cv driveline- Jess

[burrellsjeep]

Originally Posted by onetoncv

these rigs are touchy -you need an sye and proper pinion angle to match with a cv driveline- Jess

Thanks Jess,

He will be getting one as soon as his money permits him to. But yeah this was my first response to him my self.

[Lake_v2]

Had same vibes, only under accel and most any speed, was so much a death wobble as an annoying vibration.
I thought i was fighting heavy angle on stock shaft on my yj, when i dropped the skid to install the cv kit on the tcase, found that the trans mount was in 2 pieces. I did go ahead with the cv kit and shaft since i already had them.
did your buddy pull his yet?

[stealthjeep1]

Sounds to me like the factory t-case mount is failing. I don't think you should have that much left to right play in your t-case. Factory T-case mounts are junk anyway. I wasted 2 of them before I upgraded to a poly t-case mount. Haven't had a problem since. It doesn't take much to wear out the factory mount.

[onetoncv]

I hear ya buddy but its still needed and nothing will change that- Jess

[Lake_v2]

Originally Posted by onetoncv

I hear ya buddy but its still needed and nothing will change that- Jess

Oh ya there was no doubt in my case, cv was needed, i was using the stock driveline with too much angle even with shims/tcase drop, shaft was on borrowed time.

[bcpd_03]

Originally Posted by onetoncv

these rigs are touchy -you need an sye and proper pinion angle to match with a cv driveline- Jess

x2 HAD SAME PROB WITH MY JUNK, WITH 4'' SKYJACKER AND ALSO A BAD TRANS MOUNT. new SYE SHAFT AND TRANS MOUNT,drives like new now. good luck