JKOwners Forum banner

Diagnosing Death Wobble and Fixing Non-DW Shimmies and Wobbles

158K views 217 replies 72 participants last post by  TheSecretSavage  
#1 · (Edited)
The Inspection Checklist is in Post #5 of this thread.

Most people would benefit from watching these two videos. The videos are kind of long at 18-19 minutes each. Hopefully, they are thorough enough to help.

PLANMAN explains Death Wobble Diagnosis and Inspection Jeep JK Wrangler Part 1 - YouTube
Part 2, PLANMAN explains Death Wobble Diagnosis and Inspection Jeep JK Wrangler - YouTube

I'll start out by explaining that Chrysler decided to use a 14 mm trackbar bolt, with a trackbar bushing sleeve designed for a 9/16" bolt, and the trackbar bracket bolt holes are somewhere around 15-16 mm large. This is a sure recipe for DW if the trackbar bolts are not properly torqued and periodically re-torqued to 125 ft. lbs.

Stock JK bolt in stock trackbar bracket hole - YouTube

HITMONEY suggested I do a Death Wobble Write Up Dept. thread.

It is a good suggestion because my DW posts are buried in other members' threads and in some PMs.

So, here are some of my posts and PMs regarding DW.

I will also include info on non-DW shimmies and wobbles in the thread.

I will clean it up as I go, but it should be helpful nonetheless.


Death Wobble is no mystery.

It is caused by loose bolts, damaged components, or improper installation.

Look at the picture below and follow along:

Image


First, the tie rod (green) has ends that attach to a knuckle on each side. As you could imagine, if either ends of the tie rod were broken or bad, that could be a culprit for a shimmy (not Death Wobble). A common place to damage the tie rod is on the driver's side at the adjusting sleeve (in the picture, just to the right of the red swaybar link). That sleeve (maybe not the correct term for it, but you can see what I am talking about) allows the width of the tie rod to be expanded or contracted. There are threads on that end that can be damaged, causing play on that driver's side and allow an up and down, or circular play movement. Again, this would cause a shimmy, not Death Wobble.

Next, look at the drag link (purple). On one end, it attaches to the pitman arm (lavender), that attaches to the steering gear box. On the other end, the drag link attaches to the passenger side knuckle. When you turn your steering wheel, a shaft turns that goes to the steering gear box. The steering gear box turns the pitman arm, and the pitman arm pushes or pulls the drag link, which pushes or pulls the knuckle. Your steering wheel is straitened by loosening the two nuts on the sleeve/turnbuckle on the drag link and rotating the sleeve/turnbuckle to lengthen or contract the length of the drag link. If either end of the drag link is damaged, this would cause a wobble or shimmy, but not Death Wobble.

Next, look at the trackbar (aqua). It attaches to a bracket on the frame on the driver's side and to the axle on the passenger side. The purpose of the trackbar is to center the axle on the frame. With the axle centered on the frame, it provides some resistance to the steering system to allow you to turn. If there was no trackbar and you turned the steering, the whole front frame would shift. As a result, there is significant force applied to the trackbar in driving and steering.

Now, imagine that the bolts that hold the trackbar are loose in their bolt holes, or that the bolt holes are wallowed out (oval), or that the bushings at the trackbar ends are damaged, or that the bracket at the axle side has come loose because the weld has broken, or that the bushings are all twisted up because the rig has been lifted without the installer loosening the bolts and then retightened them at the new ride height. All these things would allow play in the front trackbar. When you steer or go around a corner, these loose or broken things would allow the axle to shake or slide side to side. If you hit a bump in the road, it could knock the trackbar towards the driver's side. Then, the rest of the suspension (springs, etc.) would try to bring the trackbar back to the passenger side. If you were going at any sort of speed, you could develop a kind of harmonic resonance as the axle more and more violently slide/rocked/shaked from side to side. It would feel like your whole front end was being voilently torn apart. You would have to bring your vehicle to a complete standstill to stop the harmonic resonance. This is Death Wobble.

Even one incident of violent Death Wobble related to the front trackbar can cause significant damage. The voilent harmonic resonance of the back and forth shaking is more than the trackbar bushings, bolt holes, and brackets are designed to handle. A severe Death Wobble occurance can crack or break the welds on the axle side trackbar bracket, or the bolt can wallow out the bolt hole in the bracket, or the bushing can be permanently damaged.

This is the most common source of Death Wobble because inexperienced installers either do not remove the bolt from the trackbar when they install a lift--leaving the bushing pinched in the bracket and bound up, or they do not properly torque the bolts after the lift has been installed with the tires on and the full weight of the vehicle on the ground at ride height, or (maybe the most common) they do not retorque the trackbar bolts after the first 50 miles, after every heavy wheeling trip, and at every oil change interval.

Next, look at the lower control arms (purple) and the upper control arms (light blue). In the picture, they are aftermarket arms with a heim joint on one end. However, the stock control arms have a rubber bushing at each end. When the control arms are properly torqued, the bushing is somewhat pinched in the mounting brackets on the axle and the frame. Sometimes, an installer will make the mistake of not loosening the bolts for the control arms when they install a lift. What happens sometimes is they really bind up the bushings because they are pinched/sandwiched at stock ride height, but then forced to the new lifted ride height. These bound up bushings can cause weird handling, bushing failure, and lead to Death Wobble. The proper way is to loosen the bolts, install the lift, reinstall the wheels so the suspension and jeep are at the new ride height, rock the vehicle/suspension back and forth and side to side, then re-torque the bolts to spec, then after 50 miles re-torque them to spec, then after every oil change or very heavy wheeling trip re-torque them to spec.


Improperly balanced tires, too much air in tires, bent wheels, improperly installed wheel spacers, bad tires (with separated plys), and poor alignment specs (caster, camber, and not enough toe-in) can cause wobbles and shimmies that lead to Death Wobble. However, these precipitate Death Wobble, but they are not the cause of Death Wobble.

Although not specifically identified in the picture, the ball joints that are at the top and bottom of each knuckle where it attaches to the axle C can go bad. Bad ball joints can cause shimmies, wobbles, but usually not full on Death Wobble.

Next, allthough not identified in the picture, the unit bearings can go bad and be a cause of shimmy and wobble, but not Death Wobble.

Hope this helps--assuming you read it all.

Death Wobble is no mystery.

The reason that the steering stabilizer masks it is that it can absorb some of the side to side voilent harmonics of a loose trackbar or damaged mounts. However, this masking is dangerous because it will not prevent the eventual failure of trackbar bracket welds and bolt holes from trackbar Death Wobble.



It is extremely important to immediately diagnose and fix Death Wobble.

Even one episode of DW can damage other components.

Multiple episodes of DW are almost guaranteed to damage other components.

Multiple episodes will often damage your:

  • ball joints
  • tie rod ends--including the adjusting sleeve end on the driver side
  • trackbar bushings
  • trackbar bracket bolt holes
  • steering sector shaft (where the pitman arm attaches to the steering box)
  • steering stabilizer
  • front lower control arm bracket bolt holes
  • unit bearings
  • trackbar bracket welds
  • drag link ends

Hellbound13 is an example of a member who with 5-6 episodes of trackbar related DW on a stock jeep ended up "chasing his tail" for many, many months. He ended up replacing almost everything in the above list--sometimes more than once.

Without repairing/replacing everything that was damaged at once, the remaining damaged components continued to cause DW problems, further damaging the remaining components.




This is Death Wobble (and the guy is extremely foolish for repeating it on purpose):

Death Wobble - YouTube
 
#42 ·
I have gone through and tightened every bolt I could find.
shimmy started the day I mounted the 37's. It has diminished as I got everything tightened to spec per the write up.
But I still can't get passed 72 on the highway.
shimmy starts around 40-45, diminishes from 50 to 70, and then starts up again around 73.
I have to check the rim to make sure they are okay. On wheel (of 5) had to be sent back due to dent from shipping, the replacement had to be sent back because it was really bad. So I am now wondering if other rims in my set are not well centered.
I am hoping that worst case I have to get a new set if wheels. Maybe alloy this time. Supposedly alloy wheels don't warp but steel wheels can.
 
#47 ·
Took it to Piedmont Truck tire today. Rotate and balance. That finally did it. Just have to buy 4 lugs because I lost the lug key and said okay to the "last resort" tool.

I was correct in my assumption that since PTT does big rig tires and wheels that my 37's would be no problem.
$40 for the job.
Next test will be 80MPH. Passed the 60MPH test.
 
#48 ·
Sweet. I have had some pretty funky things happen when rotating and not checking balance. It's amazing what a slightly out of balance tire can do to your ride quality.
 
#52 ·
Well, the shimmy is back. Starts at 40. smooths out at 50 and comes back above 70.
Everything is tight. Do I need to swap out the Rock Krawler progressive rate springs and go to a stiffer single rate spring? Is there a 2.5" lift single rate spring?
Moog tie rod ends and ball joints maybe?
 
#51 ·
Awesome post, Plan!

I am just embarking on my DW investigation, unfortunately! It started two weeks ago after two days of wheeling the black hills at jeep jamboree. I have had my jeep lifted for about a year now with no issues until now.

I am running a 3.5" clayton lift with all adjustable arms, and clayton track bar, as well as the clayton high steer kit with their weld on track bar mount on the axle side and JKS brace on frame side. I have retorqued all bolts to factory specs, as well as had my Fiancee cycle the wheel back and forth while inspecting all conection points. I did not spot any movement out of the ordinary.

Could a "loose" sector shaft cause DW? Mine has always had the "clunk" to it, but it seems worse after the wheeling trip. I did not see any excessive movement of it during inspection, I can just feel it in the steering wheel.

Also, if I remember correctly, my caster is around 6-7 degrees. I will try getting it around that 4-5 range. But like I said, it has not death wobbled since lifted for the past year.

And one more thing. What is the procedure for checking the unit bearings once the calipers and rotors are removed?
 
#54 · (Edited)
First, I want to say this looks like a great write up. As i'm reading thru it, it seems like a lack of maintainence may be the root cause of my issues.

Re-Torquing the Track Bar Every Oil Change and/or Wheeling Trip? Are people really doing this? Seems like alot of work!

I'm at just over 45K miles (not quite 2 years) since the last time my front end has been torqued in any way (I don't own a torque wrench).
 
#55 ·
Re-Torquing the Track Bar Every Oil Change and/or Wheeling Trip? Are people really doing this? Seems like alot of work!
It maybe takes all of 1 minute to re-torque the front 2 trackbar bolts. You can buy a nice torque wrench for $99 shipped right now from one of the guys in the Vendor Section.


Sent from my iPhone using Tapatalk
 
#57 ·
With the exemption of off set ball joints, and testing other wheels, I believe Ive done everything you listed. I installed my RK 2.5 aluminum a couple of weeks ago and had immediate DW. Added to this lift was a PP trackbar bracket and a sector shaft bracket that has since been removed. Once the steering bracket was removed there was a huge difference. I however still get the DW while hitting a ripple if not a pothole on a winding road. I gave up on diagnosing myself and brought it to my local 4wp four times now. They swear the aluminum trackbar in my kit gives too much (if miniscule) flex to cause this. I am at a loss what to do, as it drives gorgeous on straight roads with bumps, but as soon as there is a wave in a turn, all hell breaks loose. Ball joints good, castor good, jam nuts cinched, aligned, TREs good to go, axle centered, balanced tires three times to be sure, 30 PSI, wheel straight, toe in good. Even tried turning ESP off to see if the computer was causing problems. I'm at a loss.
Is it possible the the aluminum threads of the trackbar are more malleable where they just won't bite correctly? I thought about buying their steering kit, but it is for 3.5 lift and above. I would talk to them directly but they are at SEMA and I need my DD drivable in this pothole forsaken city. May be return my aluminum for a steel TB?
Thanks in advance for your help. I've been beating my head against a wall too long over this. That c-4, and det cord is sounding pretty good about now.;)
 
#58 ·
Even one episode of violent DW can damage other components. The only way to fix the problem is to inspect everything in one sitting.

Have you checked for...?

cracks or flex in bracket welds
damaged axle side upper control arm bushings
too much caster (more than 4.5 degrees)
ovaled bracket bolt holes

and all the other items in the inspection checklist?

When you had someone cycle the steering with you underneath the front end inspecting each component visually, manually, and auditorily, were there any clunks or unusual movement/play?

Have you replaced the stock 14 mm bolts with 9/16" bolts?
 
#62 ·
Seperation of bushing question

Planman - great information. Working through your DW checklist again and have a question on what exactly is bushing separation? Is it the the metal sleeve that goes through the middle of the bushing separating from the bushing or is it the bushing having play between the bushing and the trackbar/control arm.

Below is a pic of my track bar with pressure applied by a screw driver. Would the gap shown be separation? Only happens on the side with the arrow, no gap on the other side with pressure applied.

Thanks,
 

Attachments

#63 ·
Planman - great information. Working through your DW checklist again and have a question on what exactly is bushing separation? Is it the the metal sleeve that goes through the middle of the bushing separating from the bushing or is it the bushing having play between the bushing and the trackbar/control arm.

Below is a pic of my track bar with pressure applied by a screw driver. Would the gap shown be separation? Only happens on the side with the arrow, no gap on the other side with pressure applied.

Thanks,
The concern is separation from the bolt sleeve in a bushing that is made of rubber (i.e. Clevite rubber bushings on stock or aftermarket arms).

Your pic above is not an issue. When the bolts are torqued to spec--125 ft lbs--there is no problem with a polyurethane bushing.
 
#65 ·
Have a ? when going through the OP it says there should be no movement in the tie rod correct? I can move both the tie rod and drag link by hand and the rubber seals or bushings around them look flat. is this correct or is this the error in my shaking? :beer:
 
#71 ·
Up and down like when you pull your finger and the knuckle pops.

Here is a sample drawing of a tie rod end (not a JK):

Image



If the ball shape at the bottom of the stud can be pulled up out of the cradle, the end is bad.

End design allows the tie rod rotational play so that the suspension can cycle without breaking off the end.

However, if there is side-to-side play in the cradle or there is in-and-out (up-and-down) play of the stud in the cradle, the end is bad.
 
#74 ·
Got alloy wheels coming now. It seems there can be issues with bolt hole precision on steel wheels. Also, the same shop that will do the mount/balance on the new wheels, also has a mechanic that has a skill for diagnosing and resolving shimmy on everything from passenger to PeterBuilt.
Hopefully the Wheels eliminate the last of the shimmy.
Everything else is tight. All the bolts. Even did the 9/16th swap on the track bar.
Another hint that it could be the wheel is that I feel the vibration in my seat too.
I will report back the results.
 
#75 ·
what happened with your steel wheels? i looked through this thread but couldn't find a lot of info on your problem, looks like you're on another forum too? anyways, i ask because i have also been chasing a shimmy/DW for months now and have had a few issues with balancing my tires/wheels and everything else seems to be ok, or at least they were last time i checked, can't say the same now.
 
#78 ·
It is not uncommon for steel wheels to be untrue/bent.

Whenever you buy wheels--especially steel wheels--it is important to have your tire shop run them on their balancing machine before mounting the tires to check for bends/untrue or other problems so you can return a bad wheel before it has a tire mounted on it.


Sent from my iPhone using Tapatalk
 
#80 · (Edited)
Here is a video of a stock 14mm trackbar bolt in a stock trackbar bracket with a 9/16" hole.

This is why it is important to remove the trackbar to inspect the bracket holes for ovaling.

This is why it is a good idea to replace the stock bolts with 9/16" grade 8 bolts.

This is why it is important to re-torque the trackbar bolts at each oil change interval and after every major offroading trip.

Because dealers rarely remove the trackbar to inspect the bolt holes and replace the stock hardware with 9/16" bolts, they miss the most common source of DW.

Stock JK bolt in stock trackbar bracket hole - YouTube
 
#86 ·
#87 · (Edited)
I just bought my rear,(I already braced/changed fronts) T.B. replacement bolts today. After picking up my replacement drivers side exhaust manifold! (How many others have cracked???), Seems like all of them? Shouldn't some of these things be recalled?
 
#88 ·
so i've had death wobble issues at least two or three separate times and usually just too broke to fix it so i just torque the shit out of everything and slap a new stabilizer on till it comes back... i know i know terrible idea but i'm a broke college student that needs to get around town. anyways i've finally saved the funds and now have the time over xmas break to really take care of this and as i've had it so many times i want to address the issue as wholly as possible so this is what my plan is and i'm hoping you can verify if its good or not. thanks!

poly:
- steering (tie rod and drag link)
- ball joints
- track bar relocation bracket
- F9 hardware kit

teraflex:
- complete flex arms and track bar
- already have front LCA and TB