Yes I searched, and this death wobble post is real.
TJ with 4 inches of lift running 33x12.50 bias ply swampers. Dynatrac D44 front end with custom hi-steer and trackbar. All ends of the rods are hiems. The steering and all is well engineered and everything is tight. Rig was aligned professionally at a good 4x4 shop. Don't have the specs on me.
Took it out on the highway for quite a bit of driving, no problems. Steered great, ran up to 75 without any vibes or issues, hit all kinds of potholes, no problems.
After wheeling it, left the sway bar disco'ed for a 20 mile trip (tires aired up). First pothole the right side went through at 25 mph - BAM - bad death wobble.
I know what DW is and I get it when the sway bar is disco'ed, seems always when the right side runs into a bump.
Track bar and drag link run from the frame/steering box on the left to the axle on the right.
Due to a minor measuring error with the sway bar, it actually kind of pre-loads the axle. The axle mount for the right side disco is a half an inch higher than the left side, so when hooked up the sway bar tends to push the right side down and pull the left side up. Now I'm afraid to fix this problem, which I was going to do by cutting and welding short the sway bar link.
I can't dial more caster in without cutting up the upper control arms, they are already as short as they get.
Suggestions? Cut away at those UCAs or what?

Don't say "just run with the sway bar on" - seems to me there's a real instability here the sway bar just masks.

YOu could get more caster by cutting and rotating the knuckles.

Originally posted by Mo
YOu could get more caster by cutting and rotating the knuckles.

Thanks, but beyond my personal abilities and budget right now. Besides, its a high pinion diff and it actually angles up a bit, so pulling it down a couple degrees in caster would actually give me a zero degree angle on the pinion.

Kinda wondering if there's anything else I should try before I try to dial in more caster.

Are the trackbar and draglink at the same angle? You got a drop pitman arm on there?

Custom pitman:about stock drop beveled to one side to the hiem is at zero degrees at ride hieght.
Track bar and drag link perfectly parallel (but of course the track bar is shorter, but not that much, it attaches at the inner knuckle right behind to drag link). Thought those were bumpsteer issues?

Basically, with the axles centered is there anything other than caster and toe I can play with to work on this?

Why don't you lengthen the lower control arms to add caster?

Death wobble is usually caused by too much caster, not too little. To little caster makes the return to center poor and tracking vague. Too much caster causes wobble, like the shopping cart wheels do....

Try a little less caster and see what the affect is. If the shop aligned it to factory specs (7*?) it is probably too much. From what I've heard 5* is better for lifted Jeeps. I have about 3" lift and run about 5* with no problems.

I don't know what affect it would have but the caster on that one wheel may be different than the driver wheel now. Maybe that would cause DW also.

seajeep is onto it. if you get wobbles with out the sway bar I sounds like the caster on the right side is more than the left. Try measuring the angle of each side with the axle up on stands. that would give you a good clue.

but to the solution. if you only get the wobble on the road with the swaybar disco'd. Why not just connecet it up and have no more DW?

Just a thought

Originally posted by seajeeper
Death wobble is usually caused by too much caster, not too little. To little caster makes the return to center poor and tracking vague. Too much caster causes wobble, like the shopping cart wheels do....

Try a little less caster and see what the affect is. If the shop aligned it to factory specs (7*?) it is probably too much. From what I've heard 5* is better for lifted Jeeps. I have about 3" lift and run about 5* with no problems.

I don't know what affect it would have but the caster on that one wheel may be different than the driver wheel now. Maybe that would cause DW also.

For the most part your right, however with a 3" lift and stock arms my caster was at 3.8 and it was causing death wobble. Adjusted it to around 5 and is much better, still a little squirrely on the high-way

Possible fix, according to the shop that has it (they did all the custom fab work for the track bar and hi steer, that welding was over my head).
Two issues:
1 - a misalignment washer on a drag link hiem had somehow flattened out, split, and about spit itself out, so there was some play there.
2 - They are able to play around with both caster and camber at the ball joint on the right. These are 3/4 ton ball joints, Chevy I think, there are spanner nuts that locate shims that allow for both caster and camber adjustment. The DW was happening only when the right side hit a bump. They dialed in more caster and camber on that side, and claim the DW is gone.

I'll confirm and report back.....

there is something simple you guys have not mentioned, is the track bar mount and track bar tight! I have an XJ and run a RE trackbar set up and after each trail run I climb under the jeep and retighten....it alwasy works a little loose.....half a turn of the wrench stops mine everytime

Originally posted by NothernAZxj
there is something simple you guys have not mentioned, is the track bar mount and track bar tight! I have an XJ and run a RE trackbar set up and after each trail run I climb under the jeep and retighten....it alwasy works a little loose.....half a turn of the wrench stops mine everytime

Keep a close eye on that. RE standard track bars (single shear hiem) on XJs and TJs have habit of working loose like you say, but every time that happens, it allows some slop, which slowly begins to wallow out the hole in the cast ear. When the hole is wallowed out enough, no matter what you do, its loose.
You may be at the point where you need to drill it out to 3/4, sleeve it, then tighten back down and double nut it.

Ok, I don't have a jeep, but you mentioned trailing arms, right? And trying to not run a trac bar? Doesn't that locate the axle laterally? I thought that was a definite requirement for that setup. Since no one else has mentioned it, I guess I'm the one missing something. For leafs I could see a trac bar as optional.

I did a shackle reversal on my truck, and it made all the difference in the world. Yes I did my own SFA with the shackles in front, and now I know it was wrong.

Originally posted by sfazr2
Ok, I don't have a jeep, but you mentioned trailing arms, right? And trying to not run a trac bar? Doesn't that locate the axle laterally? I thought that was a definite requirement for that setup. Since no one else has mentioned it, I guess I'm the one missing something. For leafs I could see a trac bar as optional.

I did a shackle reversal on my truck, and it made all the difference in the world. Yes I did my own SFA with the shackles in front, and now I know it was wrong.

Yes you need a track bar with coils, or a triangulated 4 link.

My steering and track bar are all custom fabbed, 1.25" solid bar, machined out ends for 3/4 3/4-16 hiems.

Ted,

I have had toe-in cause DW when caster was within acceptable limits.

I would try toe in at both 0* and 1* and see if that helps.

How are your ball joints? Seems like all your other potential wear items have been upgraded.