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Diagnosing Death Wobble and Fixing Non-DW Shimmies and Wobbles

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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
 
#206 ·
That's normal bud. I asked the same question way back. My axle bushings were in ok shape. I replaced them with JJ's and it improved handling. And tightened things up-up front.
Pain in the ass but well worth it.


Sent from AutoGuide.com App
 
#207 ·
Just wanted to thanks for a great write-up! I installed a 3 1/4" lift on my '07 JK 2 door about two weeks ago, and just this past week discovered the DW issue. Having just bought this JK from the Ford dealer where I work two months ago, I was present when it was run through the shop for check-out. They replaced all the ball joints, brake pads and rotors, and had done an alignment. Now with the lift installed, I had planned the alignment soon, then the DW struck. Thanks to your write-up, I found both outer tie rod ends had vertical movement and they have now been replaced and the alignment was completed. The DW has disappeared. If by chance it returns, I know how to diagnose the system.

Greg
 
#208 ·
how much movement should the track bar have on the frame end? I have rebuilt the polyperformance bushing and replaced bolt to grade 8 9/16. all other connections are good. I did howeve found a crack on the weld of my currie inner c.
Image


could this also cause DW? only other thing i need to check is the caster, which i have to do some research to see what the Ideal setting is for 40" tires.
 
#209 ·
how much movement should the track bar have on the frame end? I have rebuilt the polyperformance bushing and replaced bolt to grade 8 9/16. all other connections are good. I did howeve found a crack on the weld of my currie inner c.

Image




could this also cause DW? only other thing i need to check is the caster, which i have to do some research to see what the Ideal setting is for 40" tires.

Yes ... Any play in the
track bar is not acceptable.
 
#210 ·
Planman's Help Did The Trick

Just wanted to say thanks to Planman again. My JK's death wobble did return this past winter and just this past Saturday, I was finally able to go through the front end again using Planman's videos. I first replaced the trackbar bolts with the 9/16 x 3" grade 8 bolts and noticed a big improvement in steering wheel feel on the road. Then I checked the draglink ends and found excessive play in both positions. Replaced both ends with Moog parts from my local parts supplier, centered the steering wheel and road tested. What a difference! Steering is much smoother through out the range of motion. The real test was today on interstate 95. I actually increased my speed and made it a point to hit all those potholes and expansion joints in the road. Not only is the death wobble gone, but all shimmies and shocks to the steering wheel are gone too!

My total job from day one is four ball joints, both tie rod ends, both drag link ends, lower control arm caster adjustment cams, and both trackbar bolts. It may sound like a lot, but my JK has 126,000 miles on it so it really needed it all.
 
#212 ·
Hi Planman
Thank you for your great videos and advice.
My 2013 JK that I brought hit with a bent front axle that I replaced is always has a shimmy (Shimmy defined as: at 40-55mph. It will also engage the traction control at speed on the highway. Any irregularities will cause the steering wheel to get a vibration. There is also a clunking noise at from the front end at any speed. Have taken it to alignment shops and 1 tell me it is good and the other says that he can not get it into tolerance as one of the shock mounts is slightly bent from the hit.
I have been driving it this way for a year and have put 8k miles on it. Do you have any ideas?
 
#213 ·
Hi Planman

Thank you for your great videos and advice.

My 2013 JK that I brought hit with a bent front axle that I replaced is always has a shimmy (Shimmy defined as: at 40-55mph. It will also engage the traction control at speed on the highway. Any irregularities will cause the steering wheel to get a vibration. There is also a clunking noise at from the front end at any speed. Have taken it to alignment shops and 1 tell me it is good and the other says that he can not get it into tolerance as one of the shock mounts is slightly bent from the hit.

I have been driving it this way for a year and have put 8k miles on it. Do you have any ideas?


I'd suggest you go through the inspection checklist at the beginning of this thread.
 
#214 ·
Great videos on the Death wobble inspection. We have change alot of the parts and problem went away for a short time, now it is back. I have read that a bad ABS wheel sensor can also contribute to the death wobble as it incorrectly applies the brake on that wheel end. It usually happens at hiway speeds hitting a pot hole or bridge expansion joint.
What are your thoughts on the ABS ESB/BAS light issues?
Thank you
 
#215 ·
First of all WOW!!! Best write up I've read. So I got an odd one. I have a09 Rubicon Unlimited and when I brake I get a wobble in my driver side tire. I know because the brand new unworn spare I put on to see if was tire/rim related has chunks missing while the other side does not. Has synergy track bar and drag link, rock krawler lift with RK track bar.

Any suggestions would be great! I don't know if it falls into this category or not as it seems to just be one side.