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Thread: TJ/JK Death Wobble: A cure

  1. #1
    Senior Member SavageSun4x4's Avatar
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    Default TJ/JK Death Wobble: A cure

    Enough is Enough!

    The Jeep has been living on the edge of Death Wobble for nearly 2 years. Kept away, by keeping tires balanced and rotated every 5 k miles and keeping everything tight and ship-shape in the front suspension. Additionally the Jeep is now on its 3rd Track Bar. However sometimes the road is just too much for it to handle.

    While out in Pomona, Ca attending the Off Road Expo I was driving I 10 which is in dire need of repair. The road is rougher than a Nyquil hangover and no ones friend, Death Wobble, is trying to hitch a ride with me at about 70 mph. Of course it picked a great time to do it as I was lifting a cup of near boiling coffee to my lips.

    Suddenly I find myself trying to steer, dodge boiling coffee and traffic at the same time. Ive got 7 or 8 cars around me that are watching the Jeep Rubicon do the Death Wobble 2-step, coffee is everywhere but mostly on the inside of the windshield, my lower lip and between my legs which is causing me to lift out of my seat.

    Finally I get the Jeep settled down enough to pull over in the wish I wasnt here lane. I get out to do an inspection and of course normal cars are whizzing by only inches from my burnt body. At least the wind is making my crotch and lower lip feel a little better.

    Turning the Jeep around at the next exit and heading back to the motel to change clothes, and try to figure out what to do about my lower lip. I also need to think about what I can tell my wife that she will believe about why I have a scalded crotch.

    The genesis of my problem is in the frame side of my track bar mount. I run an OEM track bar and the weak side is the tie rod end that affixes to the OEM C mount welded to the frame. The small tie rod end is no doubt in a constant struggle to keep the Dynatrac ProRock 60, 37 MTRs and Walker Evans bead locks running on the straight and narrow. Rapid wear in the OEM tie rod end is clearly expected.

    After much looking and wrestling in my mind for a stronger and better solution I finally came up with a hoped for panacea:
    I decided to build my own track bar!
    I contacted 4 Wheelers Supply and they suggested I look at the FAB offerings from JKS.
    I turned to JKS and went to their FAB Parts to see what I could find. From their page I picked:
    1) JKS Frame Conversion Bracket, Part # PN OGS925*
    2) JKS Adjustable Trackbar Kit, w/ 2.5" Johnny Joint # OGS950*, $175.00
    *JKS no longer carries this part. The part is now available from: Gen-Right under SKU: SM1004

    NOTE: These parts are also available for the JK. I have a writeup and pics if anyone want to see them let me know...

    Install:
    1) Remove old TB and cut off the TB OEM frame mount. On close inspection of the OEM frame mount it was noticed there were 2 long cracks in the upper portion of the C. One was so large as to be able to slide several sheets of paper into it (see foto)
    2) Use JKS conversion bracket and fab it to the Rubicon frame.I also boxed the frame at that point to give additional strength where we attached it to the frame.
    3) Measure and fit the new JKS track bar. I also strapped the Johnny Joint end for added strength.
    4) Cut and notch TB for the massive 2.5 Johnny Joint and weld up the new TB.
    5) Install TB, check front wheel tracking, toe, and adjust caster

    The Results:
    So far DW has failed to show its head and all the symptoms that so often hung around have disappeared. The first drive after the install I noticed instantly it was smoother and turned better. No doubt from not having the looseness of the tie road end. Which by the time I removed it 1 finger would easily move it around. Not the best scenario for front end stability.

    Conclusion:
    Is this the end of Death Wobble as we know it? Hard to say, but certainly its a giant step forward for DW that has its origins in the track bar. I now have a solid mounting point at both the axle and the frame, a strong OEM rubber based bushing on the axle and a large Johnny Joint on the frame. It is a major upgrade for about $200 bucks worth of parts and some welding.

    Having done it and knowing what I know now and, if I had to do it over again I would have done it a long long time ago!

    ** Note: This will only solve Death Wobble problems that originate with excessive track bar induced oscillation.

    Note the limp Richard bushing

    08112006150-2.jpg
    Look at the piece of paper pushed into a CRACK on the TB C mount
    08112006158-2.jpg
    The kit I assembled
    07112006141-2.jpg
    Welded in and frame boxed
    08112006159-2.jpg
    NOTE the welded strap around the bushing assembly
    08112006162-2.jpg
    Finished assembly
    26062007379-2.jpg
    Don

    '15 Jeep Unlimited Rubicon Hard Rock...OLD SCHOOL 6 Spd Manual Trans
    17 Oaks Ranch Companies LLC

    www.savagesun4x4.com

  2. #2
    Senior Member HillBillE's Avatar
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    Bump for relavance.


    As long as the people remain armed,
    government knows that it cannot rule over the people by force.
    Those who stand in defiance of unconstitutional laws
    do so out of duty, honor, oath and love of country.


    "Certified Jeep Junky!"


  3. #3
    Senior Member SavageSun4x4's Avatar
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    DW is both simple and complex set of issues. What needs to be done is to systematically go thru your suspension one component at a time until the issue is found.

    While I know you have already done this I will say for all:

    1) And step 1 is to insure your wheels are balanced and rotated

    2) Check caster and toe to see if its within OEM specs for any tire 32" tall or less. More than 32" and you will need to reduce your caster

    The following is ONLY some suggested starting points in setting caster based upon tire size:

    37 in: 5 degrees [I run 37 BFG KM2s, 36.8 in diameter tire, and 18 lbs of pressure]
    35 in: 5.5 degrees
    33 in: 6 degrees
    <33 in: Adjust to factory specs

    This is the basics and quite often will solve DW. BUT if it does not, then its now time to get down and dirty:

    1) ANYTHING attached to the front frame that is a member of the suspension family can cause or contribute to DW. In addition ball joints can be an issue that initiates DW or contributes to it.

    2) Steering Stabilizer: The OEM one is the same used on many screen doors across the South and when they no longer work on the screen doors they are shipped off to Jeep to be installed on Wranglers.

    The next and most often recommended SS is the Rancho 5407 which is also the same SS for most other brands...Rancho is the largest shock producer in the US and most shocks are relabeled Ranchos.

    For the more serious and those who run the big meats or just want a top quality SS then order up the Rancho 5401. Note the comparo between the Rancho 5407/5401

    Problem solved yet? NO! Ok then on to the next likely culprit and the genesis of most DW issues.

    TRACK BAR: First look at the OEM TB. What we have is a tie rod end attached to the 'C' frame mount. Right off the bat you have the prime frame suspension connection that ROTATES from the vertical at about33 degrees and rotates 360 degrees. This is called OEM DW. In other words is part of the Jeep guarantee. NOTE this setup is common across the line up of cars world wide.

    For a cheap and perm fix you can do this: http://www.savagesun4x4.com/enter/fa...r_install.html

    Baring this solution you can just replace the TB.

    For you JK owners Teraflex offers a kit (and other companies as well) to simliarly solve the problem. I just installed one on a client JK a couple of weeks ago along with the JK frame brace see pic.

    The advantage in both of these installs is the removal of the TRE and convert it to double-shear bolt on a horizontal plane.

    If you want to see how dangerous the 'C' mount can be, check the pic below with a crack in the C mount and a piece of paper slid into it. Note the pic with the C mount replaced with the horizontal 2.5 in Currie Johnny Joint I used on TJ's.

    Problem solved? NO? Ok, now we really get into the weeds as several on here have mentioned, such as the sage advice HillBillE provided: Uneven or weak, Springs, shocks, worn bushings, bad ball joints etc etc etc.

    HOWEVER my $ sez you will not need to go that far, chances are by the time to finish the TB fix or install a replacement problem solved. The reason is because the SS and TB are the 2 components that are there to STOP DW, the rest just contribute to the problem. The SS/TB can and will initiate, cause, contribute and SOLVE the issue...you see how critical they are.

    Understanding the root cause:
    The ROOT cause of DW is an imbalance condition. Often it is initiated when you drive over railroad tracks or a "crease" in the road from the contraction of road surface materials. The hitting of a manhole cover or pothole are other examples.

    What takes place is the impact forces the tire backwards and to the left or right unless you were to hit it exactly dead on. The L/R motion brings with it the OTHER side (tire). As you move forward the suspension tries to straighten out the tires. BUT Newton's laws of motion begin to interfere.

    The 3rd law states "Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first." or for every action there is an equal and opposite reaction.

    When an impact causes one tire to move L or R, then the other tires is forced to move along with it, but it exerts its own force, Newton’s 1st law of motion: "Every object continues in its state of rest or of uniform motion in a straight line, unless it is compelled to change that state by forces impressed upon it. " As you might surmise, all hell is fixing to break loose. What the automakers and engineers do is add a steering stabilizer to absorb and slow down the violent continuing reactions…better known as DW.


    more reading: http://www.savagesun4x4.com/enter/te...le_on_tjs.html


    HillBillE has a LOT of specs and a great check list here: http://www.militaryjeepers.com/commu...t=death+wobble
    Don

    '15 Jeep Unlimited Rubicon Hard Rock...OLD SCHOOL 6 Spd Manual Trans
    17 Oaks Ranch Companies LLC

    www.savagesun4x4.com

  4. #4
    Senior Member HillBillE's Avatar
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    Quote Originally Posted by SavageSun4x4 View Post
    ........HillBillE has a LOT of specs and a great check list here: http://www.militaryjeepers.com/commu...t=death+wobble
    Yep, I just bumped both yours and mine to the top, since another DW case popped up.

    I'm with you on betting the issue is in the SS or Trac-Bar, since his just started, and will go away if he turns.

    The mount coming loose on the frame side of the trac bar is common also, at least for some aftermarket mounts.

    That's a good place to use some quality thread locker on those bolts. (mount to frame)

    One place I do not reccomend using thread locker, is on the adjustable portion of the trac-bar!

    When they break, they usually break right at the threads. Now, if it's a style that uses a TRE (Tie Rod End) like some aftermarket adjustable trac bars use, when it breaks (not if, but when) you might be lucky to have the lock nut left, or just 2-3 threads showing.

    Now, if you used thread locker, you are going to play hell getting that stub out!!

    Not what you want out on the trail, 40-50 miles from town.

    I always use Anti-Sieze on the threads, and then use the jamb nut (lock nut) to hold it tight.

    It can't turn much anyway, as both ends are captured.


    As long as the people remain armed,
    government knows that it cannot rule over the people by force.
    Those who stand in defiance of unconstitutional laws
    do so out of duty, honor, oath and love of country.


    "Certified Jeep Junky!"


  5. #5
    Senior Member SavageSun4x4's Avatar
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    Quote Originally Posted by HillBillE View Post

    I always use Anti-Sieze on the threads, and then use the jamb nut (lock nut) to hold it tight.

    It can't turn much anyway, as both ends are captured.
    I have pondered this many times and in fact have experimented with not tightening at all and I completely back my jam nut off. What's my thinking?

    As each end of the TB is locked and in fact cannot turn any more than the flexibility allowed by the bushing's at either end, then there is nothing to come loose.

    By leaving the jam nut backed off what it allows is th TB to rotate as the front axle droops. Remember the axle when drooping follows and arc as it goes down and to the REAR of the jeep. Why is this an advantage?

    The advantage here is that in some jeeps like mine and many others we articulate very well and when you artificially withhold the full articulation of the axle droop you do so by restraining the rubber bushings. The result is you CRUSH the rubber bushings and they wallow out.

    It is this that I believe is the root cause of premature OEM TB failure. The axle droop overextends the TRE causing it to flat spot internally and it fails due to premature wear as a result. The OEM Jeep will articulate in excess of the ability of the OEM TB to accommodate.

    I have run my adjustable TB for years like this and have suffered no ill effects or rapid wear. In fact the bushing never failed and the Johnny joint showed little wear and the bonus was additional, measurable droop at the axle.

    As I have said before: A well executed short arm will outperform an average long are setup.

    NOTE: I also adhered to this theory on my rear TB.
    Don

    '15 Jeep Unlimited Rubicon Hard Rock...OLD SCHOOL 6 Spd Manual Trans
    17 Oaks Ranch Companies LLC

    www.savagesun4x4.com

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