I was 16 years old in the summer of 1960 when I first experienced the dreaded death wobble. OK, we called it "the shakes" then. My Jeep had previously been through a war-World War II, to be exact-and that war had taken its toll on it both physically and mechanically. I hit those railroad tracks at about 30 mph, and the steering wheel-heck, the whole front end-shook like a dog ridding itself of water. I had no idea what caused it at the time. Later, I asked the local gas-station mechanic what caused it and his answer was: "All Jeeps do that when you add bigger tires."
Well, after the fifth or maybe even the 20th time it happened, I figured it would be a good thing on my part to fix the problem. Hey, I was 17 now, had owned the Jeep a year and naturally considered myself an "expert" Jeep mechanic. Actually, what it came down to was just a process of elimination of various worn-out parts. Now that I think about it a bit more, it was replacing the bell crank that really solved the problem, or maybe it was taking out a few shims from under the trunion bearing caps that did it.
Bell crank and trunion bearings? My guess is that half the people reading this have no idea what I'm talking about. Never mind-let's get back to the death wobble thing. There are a whole bunch of things, both individually and collectively, that can cause a front end to shake violently from side to side. So let's go through a quick check with the engine off and the parking brake set.
Get your trouble light out and crawl under the front of the vehicle. Have someone turn the steering wheel back and forth just to the point of the tires turning. What you're looking for is any loose movement. Watch the tie-rod ends where they connect to the steering knuckle arms. Watch the drag link-that's the rod that goes from the pitman arm off the steering box to either the right-side steering knuckle, or maybe the right side of the tie rod. Check for wobble in the steering-box selector shaft. Make sure the box isn't moving away from the frame because the bolts that hold it in place are loose. Check that the frame isn't broken or cracked in this area.
Now have your steering-wheel slave turn the wheel a bit harder, maybe just so the tires are starting to move a bit. You want to look at suspension components, things such as spring-eye bushings, or leaf-spring movement on the axle pads for those of you with solid axles. The independent folks need to look at control-arm bushings for movement. Watch the track bar-it should remain tight without side-to-side movement. Also check out the idler arms, especially where they mount to the frame. They are noted for wearing out when a lift kit is installed.
Now you can tell your slave-er, helper-that their steering job is done, but you need them to do one more thing. Jack up a front wheel off the ground and have them grab the top of the wheel and try to rock it back and forth. You want to watch for any in-and-out movement. If it's just the tire and wheel moving, chances are the wheel bearings need either adjusting or replacing. If you see movement where the steering knuckle and the axle join, then the ball joints are loose or in need of replacement.
But now you're saying that you didn't have any problems until you put on the lift kit and the bigger tires. I can agree with that. Did you have a front-end alignment like the lift kit's instructions said to? Lack of proper caster angle may be the problem. Are the tires properly balanced? Bigger tires put additional loads on the suspension components. Add up a little bit of wear in all the steering and suspension components, and multiply by the added leverage of the larger tires, and it just all may result in the dreaded "death wobble."
Oh, and I almost forgot about steering stabilizers. They never were designed to take out the "wobbles." However, in some instances they will work as "band-aids" to cover up the problem, at least for a while. I have seen as many as four used trying to correct a death wobble! Actually, they should be called steering dampers. Their purpose is to absorb the shock loads that the steering components receive, like when you drop a wheel into a hole or up against a rock. Not only is it easier on your arms, but one will allow steering components to last a heck of a lot longer.
So grab your slave, your trouble light, and spend a few minutes crawling around under your rig and you should be able to figure out the problem just like I did as a 17-year-old "know-it-all" kid.