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 Death Wobble Info 
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Planning for 4 1/2"

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Location: Columbus, Oh
Vehicle: 97 XJ
Post Death Wobble Info
I just ran across these, and thought they looked good.

http://kevinsoffroad.com/death-wobble-c ... mment-1946
http://www.ironrockoffroad.com/Merchant ... cklist.pdf

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Wed Apr 27, 2011 11:59 am
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Location: Charleston, WV
Vehicle: 2014 WK2, 2008 JK
Post Re: Death Wobble Info
Thought this was worth posting over here in case anyone is having issues or needs a better understanding of "death wobble"...  This guy did a A++++ Writeup.

Posted by username:planman on JKowners.com



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.

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Wed Apr 27, 2011 1:21 pm
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Post Re: Death Wobble Info
9 out of 10 times its completely caused by tires out of balance

and results in loosening something up, if you have your tires road force balanced and everything is tight, you wont have death wobble and in return of having perfectly balanced tires nothing will prematurely loosen amplifying the death wobble :bigthumb:

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Wed Apr 27, 2011 7:34 pm
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Post Re: Death Wobble Info
I've also noticed that the rougher the tire the worse it makes the DW generally speaking.

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Wed Apr 27, 2011 7:52 pm
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Post Re: Death Wobble Info
My Jeep got VIOLENT death wobbles straight out of the dealership. I was doing 70 through Cumberland, MD when my head suddenly bounced off of the side window, scary as hell!  Replaced the track bar bolt with a larger grade 8 bolt.  Wish I could remember the size. $1.10.  3 years later, it hasn't done it since.


Sat Nov 29, 2014 11:38 am
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Post Re: Death Wobble Info
Image

Seriously though ive seen too little caster be the primary cause as well

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Sat Nov 29, 2014 12:54 pm
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Post Re: Death Wobble Info
I have found that just about every component on your front end can and will cause DW if it is worn enough. Biggest contributors in my experience has been-

tires-out of bal. bent wheels, grooved or out of round tread
track bar-worn ball joint, upper mount hole egged out, diff mount hole stretched out
ball joints-worn out
hub bearings-worn out, even a little bit of slop can cause you problems
alignment issues-toe and caster out of specs. I usually set my own toe and 1/8-1/4" toe in. Toe out also works
Lower control arms-worn bushings or joints
steering gear-worn, has play

With a perfect set up where all of the front components are good except one, usually a DW situation will not show its self. You just end up with some noise or play in the steering. Problem is, when you realize you have a worn part, its usually after its been bad for sometime. By then the excessive play and feedback through the rest of the components usually wears additional parts.  Then you are just chasing the bad parts.  When I run into a DW situation, I usually start with replacing anything that appears to have free play. I have rode to the trail with no issues and develop DW on the way back home, worn part or even mud in the front wheels can cause this. I have learned one thing, trying to drive through the DW by going faster, usually just results in a stain in your driver seat.

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Sat Nov 29, 2014 9:56 pm
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