Death Wobble has me stumped

OK so the background info ...
2000 XJ, ~5.5" lift, WJ swapped knuckles and 1 ton steering.

Prior to the WJ swap I had no death wobble, zero.
when we did the swap we swapped in a set of RE1310 4.5" coils (164lb/in) and 1" spacers. Previously I had some RE TJ 4.5" coils (219lb/in) and 1 3/4" spacers. Old used Rancho front shocks. We also did New WJ ball joints and new wheel bearings at the same time
My death wobble has me and other stumped ... as it requires a specific series of bumps, or a specific sized bump above a specific speed. Currently that speed is 85kph (~55mph).

I can drive all day long at 120kph if I don't hit that specific kind of roughspot, but when I do ... it's an axle bouncing hell ride until I slow down to around 30kph (not sure I'm too busy soiling me undies). With the WJ brakes I can hear that the tires are coming off the ground as I chirp as the tough down locked up while in the air. The steering wheel actually doesn't move a whole lot, there is a shimmy to the wheel but that's about it through the whole ordeal.
It starts with "That Bump(s)" and then there is a quick shimmy of sorts (about 7 bounces), and then it just progresses and feels as if the axle is tearing itself apart.

This is Death Wobble, not just a general shimmy, shake or Vibration I can speed up up or slow down through. Once it starts, that's it, I'm along for the ride until I can stop enough. If it hits at 85kph, it's the same as 110kph ... it just takes longer to stop (thankfully the WJ brakes front and ZJ rears make that a short stop).
My thoughts now are the soft springs are causing the shocks to "fade out" of sorts, as there is no excessive side to side action on the steering wheel, making this more like axel bunnyhop. and it seesm the shimmy I do feel is more the result of the trac bar push/pulling the axle while on it torrent.

I'm going to try BDS 4.5" coils in hopes that my springs are just simply too soft for my shocks. I did replace the front shocks for a set of Pro-Comps for a 4" lifted JK as that's the compression and extension lengths I needed and the valving should be similar given the ranges of vehicles it covers (durango, dakota, JK). Caster is at 5degrees and toe is at 1/16" in. Tracbar is a custom jobby torqued to ~110ft-lbs (uses Rusty's bushings and was made using the old Rusty's bar I had on the XJ before). Bushings are all good and everything is tight. Checked by me and a few mechanics (trusted 4x4 shops not just old Joe down the road).

Any suggestions, is my thinking sound?

I've never seen DW caused by running softer springs and highly doubt that's it. It's possible your stiffer springs covered up an existing problem though. This is a tracbar thing 90% of the time, but worn/loose CA bushings can cause it as well. I'd take another long hard look at the tracbar, especially since it's a "custom jobby". Make sure you check the frame mount as well. Things can appear tight by hand, but there's a lot of force applied there! Pics of your front end may help as well so we can see said tracbar and the geometry.

Don't forget to check your caster angle on the alignment if you haven't yet. As stated above double check your track bar mounts to.

I've had some killer death wobble recently as well. I finally gave up on the poly bushing/RE joint track bar and converted to all heims. I'm also throwing a track bar brace on because the body mount moving has screwed me in the past.

My issue is similar to yours tho, my steering wheel doesn't move much with the DW, but the axle obviously does. This is pretty normal because if the axle can move side to side on its own (track bar) or the wheels can go back and forth (loose steering somewhere), then it won't really affect the wheel. Personally, I think my steering box has excess play in it. So technically, I can turn the wheel back and forth a bit without the pitman arm moving. So basically, the opposite should be true as well where the pitman arm and wheels could move a bit without the steering wheel moving. So hydro assist is also a fix I'm trying out.

TRAILREADYXJ said:

This is a tracbar thing 90% of the time, ... I'd take another long hard look at the tracbar, especially since it's a "custom jobby". Make sure you check the frame mount as well.

Click to expand...

^ This.

I've solved DW on 5 different XJs and here is the process I follow:

I lay on the ground in front of the steering and have someone move the steering wheel back and forth about 6-8".

• First I watch the track bar axle mount. Watch for movement in the joint and movement of the bracket - Ive seen those break loose more than once...
• Next I watch the track bar frame mount, look for movement in the joint and then on the mount itself. I've seen the bolts loosen as well as cracks in the mount and in the frame.
• Next I watch the steering box for movement at the frame. I've seen the bolts loosen here and I've seen the frame punched in.
• Then look at the pitman arm and TRE/heim on the drag link for play
• Then check the TRE/heim on the drag link at the knuckle
• Then check both ends of the tie rod

If you don't spot any slop/play then have the person at the wheel change the tempo at which they are turning the wheel. Also you can try with the engine running and with it off, but always wheels on the ground (not jacked up).

IF you make it through all this and don't find any issue, replace all your TREs/bushings for the track bar, drag link and tie rod - they're probably old and need it anyway. Make sure you torque properly.

IF you make it through ALL THIS and STILL haven't found the issue, replace all your control arm bushings.

Finally, if you still have a problem consider a torque/rebuild of your steering box.

Personally, I've never made it past the track bar or steering box before I find the culprit. (Once I've replaced the suspect part or welded the broken bracket and verified the DW is eliminated, I check the rest just to be sure.)

:lecture:
Personal note: it helps to have a patient person behind the wheel who will be content to just sit there and QUIETLY turn the wheel side to side for as long as you need them to. Also, get comfy down there, you want to take a good long look at each possible trouble spot!
[/soapbox]

On my 94 it used to take a very specific bump at the right speed to set it off as well.

My fix was the steering box mount was pretty much gone, allowing some play at the box mount that vibrated down into the steering

Bought the jks kit and all was better

TB/draglink angles have to be somewhat correct..
Castor..
check for bad bushings in TB, Lca, elongated trackbar mount hole..
Bad/loose steering box or possible loosely mounted(bad spacer)..
also as mention if your TB bracket(frame side) is loose look into that, you can either get the brace or tack weld it in certain areas.

As previously mentioned, caster is at 5 degrees.
TRE's are one month old ES2010L, ES2010R, ES2026L, ES2037R tube 1.5" DOM and ruffstuff tube inserts.
Bushings looked good, but ordered 4 sets yesterday (replacements plus a spare set). LCA's are 6 months old (fat bob's), uppers are Rusty's old acme thread version adjustables with new bushings 6 months ago. Toe in is at 1/16".
Have the front driveshaft out while figuring crap out (one less thing to worry about). Carry it with me and toss it in when needed.
Angles are almost flat and pretty much parallel, the Trac bar is only 3" shorter than the drag link (which is better than some OTK setups without wobble).
I'll get some pics up in a bit here so you can see what I have.

Here's what I've got so far, forgot to mention we relocated the front swaybar forward to make room for the new Tracbar bracket. My passenger side UCA axle mount is starting to buckle (this is recent and a result of the wobble) so that's getting reinforced to the tracbar bracket this week, they are also going to reinforce the LCA mounts as well.
I'll check the steering play when I get my daughter from school this afternoon (if the Cherokee doesn't go into Karnage today).

Can deffinately say I have never seen a body side track bar mount that has the track bar mount over to the drivers side so far. But your track bar and drag link look right as to each others angles.

You say you replaced the shocks as well. Are all the fasteners for the shocks tight?

I have diagnosed more of these than I can remember. Your track bar isn't parallel to the drag link so you will get some bump steer, but that shouldn't effect DW. But I would redrill the track bar bracket on the axle side down about .75 inches lower.

The method I have always used is simple. Put someone in the drivers seat with the motor off. Have them rock the wheel from side to side maybe 10 degrees. While this is happening, crawl under the front and place your hand across each joint, including the control arm bushing joints. You will be able to feel any slop in the joints. Many times the slop is really caused by holes that have been "egged" out, allowing the TRE or bushing to move back and forth. Also do the same across the ball joints. I have yet to have a vehicle where this simple test would not find the problem.

Also watch the track bar bracket for flexing or where it connects to the frame rail from flexing. It looks like you have some type of shim under the upper two holes. That will allow the bracket to flex and will ultimately lead to cracking and major problems. Where did you get that bracket. I have never seen one like it.

Also check the bushings on the rear leaf springs and the unit bearings. It is very uncommon for these to cause it.

Good Luck.

Going in tomorrow, so they can play with it while I'm away with the family. Re aligning the Trac bar was on the list. The bracket is custom made to gain as much length on the Trac bar as possible. There is no shim there, just bolts straight to the uniframe.

We also talked about reinforcing the passenger side UCA mount and tying it into the tracbar mount as well to make both excessively stronger. Will also be straightening and reinforcing the LCA mounts as well. Ryan (Karnage Fab) wants as much time as he can get to figure it out once and for all.

Thanks for the tips, I'm hoping this round will sort it out, scares the crap out of me at times and Ryan feels bad for not being able to figure it out. The guys at Karnage are great to work with, and fair on the dime as well. Between them and me we'll figure the issue shortly ... Ordered the replacement tracbar bushings to solve one more question of condition. Same as I did for all four shocks in the last two weeks. The only thing that isn't new in the last three/four months on the front end is the steering box, axleshafts, and one ujoint on the passenger side (well and the dif housing itself). Everything else was replaced during the upgrades/lift (lifted ~5.75", regeared 4.56 and WJ front knuckles w/ 1 ton steering).*

Do you like that frame side track bar bracket? Then weld it to the unibody, and add a brace to it. I could never get mine tight enough that it wouldn't move under steering loads.

There's a brace on there, it bolts to the outside and looks like it goes across to the passenger side frame. Also looks like it's made out of 2 different size tube pieces?

Though I agree, welding the bracket to the uni-body is still recommended.

old_man said:

I have diagnosed more of these than I can remember. Your track bar isn't parallel to the drag link so you will get some bump steer, but that shouldn't effect DW. But I would redrill the track bar bracket on the axle side down about .75 inches lower.

The method I have always used is simple. Put someone in the drivers seat with the motor off. Have them rock the wheel from side to side maybe 10 degrees. While this is happening, crawl under the front and place your hand across each joint, including the control arm bushing joints. You will be able to feel any slop in the joints. Many times the slop is really caused by holes that have been "egged" out, allowing the TRE or bushing to move back and forth. Also do the same across the ball joints. I have yet to have a vehicle where this simple test would not find the problem.

Also watch the track bar bracket for flexing or where it connects to the frame rail from flexing. It looks like you have some type of shim under the upper two holes. That will allow the bracket to flex and will ultimately lead to cracking and major problems. Where did you get that bracket. I have never seen one like it.

Also check the bushings on the rear leaf springs and the unit bearings. It is very uncommon for these to cause it.

Good Luck.

Click to expand...

Best info/way to determine DW on your own

I've been doing what G2WANIT listed for the last 10 years, just do it. I don't care how new your TREs are, I've seen Moogs that were bad right out of the box.

Your Track Bar/Drag Link angles are going to cause bump steer, and if you have a bad tire or if your wheel base isn't same on both sides you will get a wobble or shimmy.

Something else, your still running your control arms out of the factory location which means your control arms could be moving in the body side mounts, the alignment plates don't last long on a lifted jeep.

G2WANIT said:

^ This.

I've solved DW on 5 different XJs and here is the process I follow:

I lay on the ground in front of the steering and have someone move the steering wheel back and forth about 6-8".

• First I watch the track bar axle mount. Watch for movement in the joint and movement of the bracket - Ive seen those break loose more than once...
• Next I watch the track bar frame mount, look for movement in the joint and then on the mount itself. I've seen the bolts loosen as well as cracks in the mount and in the frame.
• Next I watch the steering box for movement at the frame. I've seen the bolts loosen here and I've seen the frame punched in.
• Then look at the pitman arm and TRE/heim on the drag link for play
• Then check the TRE/heim on the drag link at the knuckle
• Then check both ends of the tie rod

If you don't spot any slop/play then have the person at the wheel change the tempo at which they are turning the wheel. Also you can try with the engine running and with it off, but always wheels on the ground (not jacked up).

IF you make it through all this and don't find any issue, replace all your TREs/bushings for the track bar, drag link and tie rod - they're probably old and need it anyway. Make sure you torque properly.

IF you make it through ALL THIS and STILL haven't found the issue, replace all your control arm bushings.

Finally, if you still have a problem consider a torque/rebuild of your steering box.

Personally, I've never made it past the track bar or steering box before I find the culprit. (Once I've replaced the suspect part or welded the broken bracket and verified the DW is eliminated, I check the rest just to be sure.)

:lecture:
Personal note: it helps to have a patient person behind the wheel who will be content to just sit there and QUIETLY turn the wheel side to side for as long as you need them to. Also, get comfy down there, you want to take a good long look at each possible trouble spot!
[/soapbox]

Click to expand...

Have the tires checked. I had a nearly brand new set of BFG All-Terrains that I had been running for a few months that had NEVER expressed any death wobble nor had the Jeep ever had a death wobble problem. I had the Jeep in the shop for some front wheel bearings and a few other unrelated things (before I knew how to do as much as I do now). As soon as I got the Jeep back, I wasn't two miles from the shop before I experienced the death wobble, and it was BAD! It was late and the shop was closed at this point so I took it back the next day. To make a long story short it was in and out of the shop 3 more times for death wobble and the shop kept saying the tires were "out of round." I fought DW for 2 years before I finally swapped the tires out and it has never DWed again after 5 years.

So take the tires to a good tire and alignment shop and ask them to specifically check the tires for true roundness. It sounds crazy but I can attest that tires can be "out of round."

Before the WJ knuckle swap there was no wobble with these same tires. They roll without and vibe at all. We did notice a bit of wallowing on the axle end of the tracbar mount. I'm heading down to Disneyland so I left the XJ with Karnage until January 1 at the latest. Ryan was sure he find it by then. But he's going to go over everything. Ordered some new control arm bushing as well just in case so I'll drip those off on my way out of town.

Devilfrog said:

Before the WJ knuckle swap there was no wobble with these same tires. They roll without and vibe at all. We did notice a bit of wallowing on the axle end of the tracbar mount. I'm heading down to Disneyland so I left the XJ with Karnage until January 1 at the latest. Ryan was sure he find it by then. But he's going to go over everything. Ordered some new control arm bushing as well just in case so I'll drip those off on my way out of town.

Click to expand...

I had no DW before the change of the wheel bearings on my Jeep. The problem is you replaced old used parts with brand new tight tolerance parts. Used parts have room to give and can absorb vibrations masking them and keeping them from escalating. DW is simply a rhythmic vibration gone awry. Now that you have brand new tight parts the vibrations have nowhere to go but farther through the system that is your front end. Nothing is absorbing this vibration as it might have been before. This was my case and quite possibly could be yours. A simply diagnosis you could suggest to your friend who is working on it, is to simply swap the tires and wheels for another set. Doesn't even have to be the same size just a different set to rule it out.

Just saying, with DW it could be a hundred different things and the only way to figure it out what it is, is to rule everything out. This IS a possible cause and easy to rule out so why not try it? I know it sounds stupid and crazy, I mean how could tires that were on the Jeep before the change, now cause this to happen? It can, and you should consider it a possibility.