A carnival barker for a freak show steps to the microphone entreating the passerby’s to listen, to be reviled, and to be entertained by the monstrosities of what’s behind the curtain. With fear and trepidation the captivated onlookers wait nervously to see what the face of fear looks like.
This is the type of apoplectic hyperbole that newscasters, magazine writers, and certainly expert forum mechanics use when they describe the dastardly “Death Wobble”
What is death wobble?
Vehicle suspension works best when all the parts are properly fitted and compatible. When a part isn’t working with the others it causes things to go cross-eyed and a little batshit crazy. That part may be worn, broken, loose, or there may be several parts that are slightly worn all giving just enough to make the vehicle unstable. The video above shows exactly what I am talking about.
Now that you have witnessed what “Death Wobble” is let’s talk about “Why” it is.
There are multiple pieces that all tie together to keep everything tracking straight and true. When any one of these is off it shifts the workload to the other components. What happens over time is the next part fails and then the next because each failure compounds the work of the next part in line.
What are those parts we keep talking about? It starts with the steering box. Mounted to the frame rail it interpolates the rotation of the steering wheel through an output shaft that turns the Pitman arm. The Pitman arm moves the drag link. This is an adjustable length rod that runs from the Pitman arm to the steering knuckle on the passenger side of the vehicle. That adjustment is used to center the steering wheel.
The tie rod is attached to the steering knuckle and runs the entire width of the vehicle and attaches to the opposite side steering knuckle. On the Jeep we used for this article there is an adjuster on the drivers side to set the toe of the vehicle. Toe is whether the tires are pointed towards or away from each other in the front.
There are a few other components involved in the basic causes of the out of control oscillation. The track bar locates the axle in relation to the chassis, worn bushings or damaged mounts can cause the wobble, so can worn ball joints.
So how do you diagnose “Death Wobble?”
First you need someone to help you. Unless you are Mr. Fantastic your arms are not long enough to move the steering wheel and check the suspension at the same time. You need to check the steering while the vehicle is on the ground, there must be tension on the parts or the movement won’t show up that we are looking for. Before going any further make sure to torque all of the bolts to the proper torque setting. Loose parts will cause a wobble just as much as failed parts and it is hard to differentiate if they aren’t installed properly.
With the running, have your buddy cycle the steering from side to side while you are under the front end. Starting at the arm use your fingertips to feel each joint. Be careful to keep your fingers out of pinch points and away from sharp areas. It doesn’t take any pressure to do this just contact. The stronger a jolt you feel the closer you are to the issue.
Normal operation of any of the joints is side to side. They have to have that to allow the suspension to articulate and rotate. What you don’t want to see is an up and down movement at the joint. Don’t stop just because you find one fault. Go from the Pitman arm all the way to the end of the last tie rod and annotate any parts that have failed. If you see any vertical movement you know that these parts need to be replaced.
To check the ball joints you can lift the vehicle in the air. Grab the wheel by the top and bottom and try to wiggle the wheel. If you feel movement or see any movement in the ball joints they need to be replaced. You will be able to tell pretty easily as they often times will also make a thumping noise when worn as they move around in the socket. This is best done with the help of a friend who can look at the joints and make sure it’s not a loose hub. (Thanks to Rick for the input!)
The track bar should move up and down as the suspension moves but not have any sloppiness at the joints. Look for worn or cracked bushings and any other obvious signs of wear. If you torqued the bolts earlier and these were loose, it’s worth looking at the mount brackets. Take the bolts all the way out and check for any elongation of the holes. If they are this was loose enough to move. You can get these repaired and install a larger bolt to take up some of the excess room getting you back on the road safely.
What if none of this works?
Well, so far we have spent $0 to try and diagnose a wobble. If you follow the above steps and find nothing wrong it could very well be your tires. They could have a bad belt, have uneven wear or simply be out of balance. The larger the tire the more these conditions are likely to occur and be magnified through the steering wheel. One of our brand new tires had a flat spot and they were terribly balanced. At 50MPH the front wobbled but would go away at a higher speed. I ran through the above checks, determined it was the tires and took them to a professional shop to fix the issue. One replacement tire and having them properly balanced and no more wobble.
How do you protect against it?
Once everything is ship shape again there are some things you can do to prevent the issue from returning. Maintenance is paramount, lubricate the joints that need lubrication, check the torque settings when you change the oil. Keeping those components tight is one of the best preventors to premature wear. We also recommend spraying the suspension with a good silicone spray to help prevent rust and dirt from sticking.
There are some aftermarket solutions that help the steering system and allow it to handle larger tires, taller suspension, and heavier loads as well.