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Thread: The TJ Shimmy
08-27-2003, 01:12 PM #1
For any of you TJs out there that Have/Are/and Will experience the Shake.
Found at http://www.off-road.com
Remedies for the Jeep TJ/XJ Death Wobble
by Alex Parker
2001 September -- If you drive a lifted Jeep TJ or XJ, then chances are you've encountered the dreaded "TJ Shimmy" before, otherwise known as the "Death Wobble." If you haven't yet, it's only a matter of time.
The shimmy can be a pant-wetting experience for those first timers in the crowd. Those of us seasoned veterans have taken precautions to the effect, which causes your TJ's front end and steering wheel to violently shack side to side. It usually occurs at about the 40-45 MPH mark.
The only thing that seems to help in this situation is either a shot of Novacaine, which we don't recommend, or slowing down to a snail's pace and on the way home consider what follows.
I myself have encountered this shimmy more times than I choose to admit and couldn't understand how, after dumping wads of cash on a suspension, did I get results such as the infamous Death Wobble. Luckily, there is a cure, and it's fairly cheep.
I have narrowed the shimmy down to 5 major causes. The first of which is that your alignment is off. Because of the scissor type of steering on TJs, when you lift a TJ, your jeep gets toed-in anywhere from 2-3 inches more than factory. Your Jeep should only be towed in about 1/8 to 1/4 of an inch. Have your jeep aligned if you have lifted it over 2 inches with out a recent alignment.
The next possible cause of the shimmy comes from the balance of the tires. If your front tires weights have been knocked off by an extreme rock crawling incident, you may wish to have them rebalanced. Also as these big mud tires wear down, they loose a lot of there weight, and this can also cause them to come out of balance. For the most part this is the main cause of the shimmy, but not always.
The third cause is the track bar. My lift kit didn't feel the need to supply a longer track bar, they felt all that was needed was for you to merely drill a new hole in the axle bracket, this is not a permanent solution at all. I managed to blow out the ball joint at the end of the track bar within weeks of installing my lift. This blown-out joint allowed for side to side play in the steering and would only help the shimmy along. Get a track bar with a beefy heim joint that is adjustable in length. This makes for a very solid mount and should you ever wear out your heim, you can easily replace it. Several companies make track bars that are heim jointed, and they are not very expensive. Plus, you do gain a little more flex with a track bar that is properly bent to fit large lifts, and we all know you can't get enough flex.
The fourth cause is from excessive castor angles. When you lift a TJ, you need to adjust the lower arms longer, and or the upper arms shorter to put the castor angles back to factory limits. Have a reputable alignment shop do this for you, as it is quite a task that needs to be precise. You should only have to worry about this if you have a lift of three inches or more.
The fifth and final cause of the shimmy can be warped brake rotors. Jeep did not design rotors to handle massive amounts of heat very well. I have managed to warp my rotors in 18000 miles. All you need to do is get them turned and this will only cost about 40 bucks. If you are not sure if your rotors are warped, you can test them if you don't have Anti-lock brakes. All you have to do is drive down a stretch of highway and slam on the brakes. If you feel a pulsating feel through he pedal, then they are warped. However if you have anti-locks, this will be masked.
One last thing to keep in mind is that from the factory your TJ has one coil clamp on the driver side coil that holds it to the axle. I have heard that by drilling a hole and putting a clamp on the passenger side as well, the shimmy is much more controllable. However, this is not a cause, just something to mask the real cause. Keep these thoughts in mind next time you hear of someone whose Jeep is doing the Shimmy Shake or the Death Wobble, and let them know there is a solution - and it ain't ballroom dancing.On a long enough time-line,
The survival rate for everyone
Drops to Zero!
08-27-2003, 04:45 PM #2
Don't forget the flimsy weak tierod and draglink, both of which can be flexed by hand The larger the tire, combine with less backspacing, will cause the steering linkage to flex considerably when driving down the road. This will cause DW.