Alright guys heres the run down. 1990 xj, 6" lift, longarms and 1 ton UTK steering and beadlocks on 35's that are balanced professionally. Gets death wobble as soon as i hit 30 mph now. all joints are tight, all joints are tight and practically brand new. Cant figure out why it still gets death wobble. Any help is much appreciated and yes i have searched for an answer and i have tried everything so far that i can think of. thanks in advance.

 

AnY front end component can cause it. Have you replaced ball joints? I think I've read that wheel bearings can cause it. Slack in your steering box. In mine one if the big culprits was the, what I believe is called, rag joint in the steering shaft was flopping around. More detailed info I what's new would help.

 

All ball joints are new and both hubs are less than a year old ove seriously been through everything on this jeep haha Only thing im down to is the axle side UCA bushings (have them in the house just havent installed them yet) and the steering box having slack in it. But just checked the steering box and it has no play in it at all

 

It is usually the trackbar that is culprit. Its bushing, bolt or bracket.

 

I see nothing about the track bar or an alignment, are you still using the stock track bar? And did you get an alignment?

I aired down my tires from 40 psi to 35 and that prevents most of my DW/shimmy. I know its out of alignment but will be getting it done after I lift it again. That may help.

 

forgot to mention the track bar. Its a rubicon express double shear with the hd bracket welded and bolted to the unibody. I just put that back in today after tightening up the bushing on it. Yes it has had an alignment

 

So after talking to a few others about the issue there were questions raised about the control arm bushings. I know the axle side UCA bushings are bad but i have them and just havent gotten around to installing them yet. Possibility to the cause or not?

 

Is the track bar and steering link at the same angle?

 

My upper axle bushings recently split the rubber and ejected chunks of it after impacting small trees. Drove on them for another week before I noticed something. Did not have DW just a wandering back and forth and something 'funny feeling' in the steering.
DW is an oscillation of the axle/suspension that is initiated buy a bump.
Something is loose, worn or in conflict with one another as Andrewmp6 mentioned.

 

Precisely.

Mister OP what does "had tires balanced professionally" mean? Where and what technique? A lot of big offroad tires are grossly out of balance from the factory and yesterday's passenger car balancing machines aren't accurate enough for them. If this happens when you hit a certain speed the tires are generally the culprit, although it is the slop in the front end letting the vibes turn into DW.

 

So whats the caster reading on the alignment sheet???

 

Okay so today took the whole front end ot, i mean everthing... even the cross member. And i did new UCA bushings and a new trans mount. when putting everything back together i made sure every joint was tight and still good.
Tires were balanced at discount. Also, im not sure of a place around here that does anything but standard tires for cars. And i cant remember what the caster angle was on it and i cant find the sheet from it. Should have put it somewhere i would have remembered where i put it haha

 

Oh and i should mention.... took for a test drive and death wobble is better but still there. On a smooth road i get to 35 before DW starts. Even when it starts its not as bad as it was before but it is bad enough that i wouldnt go any faster than that

 

Anywhere in town have a Hunter RoadForce machine? I don't know what Discount uses. People have this problem with Walmart, too, as their cheap machine doesn't do well on large tires.

Trackbar torqued properly? Are the TREs in like-new condition?

 

The fact that it starts up on que at 30mph on smooth road leads me to believe that it'd be linked with an out of balance tire. Have you tried a different set of tires?

In my experience, most cases of DW was caused by bad control arm bushings and poor caster or a loose track bar. (You just replaced the bushings so that's not it.

I'd check the caster with an angle finder on top of the ball joint. I set mine as far as I can while still maintaining a decent pinion angle. Which works out to be about 7-8*.

So, swap on some different tires and check the caster angle.