Likely the number one tech topic for Jeeps used on the street is Death Wobble. Good Lord! What kind of a name is that? Death Freaking Wobble? Why did I buy this thing anyway? If you have ever experienced it, it is the perfect name. Just see if you can stay on for 8 seconds
Do you have death wobble?
“my steering wheel seems to pulse when I’m doing 30.” Not Death Wobble. “When I hit a big bump, my Jeep wants to change lanes.” Nope! If you’re asking these questions, fear not… You do NOT have Death Wobble. “My God! My !@#$% steering wheel is an absolute blur and the vibration…. Did I just cross the event horizon of a black hole?” If you’re thinking this, you have Death Wobble.
Death Wobble is a violent shaking of the front wheels. It is akin to wheels frantically wobbling back and forth on a tweaked shopping cart. This is Death Wobble. By the way, the wheels on that cart are called Casters, and that is an important thing to remember.
What is the cause?
Despite what you've read, worn steering parts are not the cause of death wobble. In fact, parts are the first victims and exponentially wear due to the root cause of death wobble. The wobble is a result of forces that are happening in every vehicle. Jeeps and trucks exacerbate the problem with steering geometry and large tires.
Caster is part of the steering geometry setup. It is the rotation of the axle and affects is designed geometry by rotating the knuckles, essentially, to push the weight of the vehicle forward of the centerline of the axles/wheels. The weight then “drags” the vehicle around behind it. Caster changes not only affect pinion angle, but also the tire contact patch on the road on where the contact is on the tire. If the caster is set incorrectly for the overall setup, it allows the tire to begin to wobble. Think improperly loaded trailers and wag or recall the shopping cart caster example from above. However, new steering parts with little play keep things in check. That is, tie rod ends, Control arm ends, drag link ends panhard (track bar) bushings and even sway bar links. Steering stabilizers also help control the forces and keep the wobble from manifesting. That is not to say though that the forces aren’t there. The additional forces from improper geometry wear all of these parts exponentially. When they wear to a point, the tires are set free. Free to shake, free to scare the hell out of everyone, free to absolutely pummel the steering parts with every episode and make the problem worse.
My buddy said...
“Its track bar bushings.” “It’s Steering stabilizer.” “Replace the tie rods and it will go away.” Social media is dripping with empirical fixes. Here is why everyone is wrong and right.
As stated, the parts are being exponentially worn. And with each destroyed part the next in line gets hit even harder. Replace one, if you’re lucky the worst one and the first in line, and the problem is “fixed” the truth is it is controlled buy likely for a shorter period of time and the other parts are continuing to wear.
The Fix
Here’s the bad news. You can not eliminate the forces at work here. You could fully change how your vehicle tolerates them but that comes at an exorbitant cost and even with a full geometry/suspension change there are no guarantees. The better solution is to know what causes it and what controls it.
Tire Wear
Tire wear changes the contact patch. It happens daily as the tires change size, and patterns develop. Ensure that they are not wearing out and that the tire pressure is set correctly. Tires are designed for weight classes and uses of vehicles, not specific vehicles. For lighter rides like Jeeps with bigger tires, it is likely that the tire can handle of vehicle 50-75% heavier. Running maximum pressure then makes no sense. If the tires are bad, give a kid a cool swing and swap them out.
Worn Parts.
All of these beating have worn your junk out. (parts you pervert) Replace it… all of it. Every part has tolerances. But if each part is at the loose end of its tolerance, which is likely where it is, then the stacking of parts and their associated wear makes a tremendously loose system. The system as a whole then quickly succumbs to the forces at work against it. Replacing one part and then allowing these forces to beat it up results in short life cycles, less cash in your pocket, and the possibility of another temper tantrum. Replace them all! Anything worn should be tossed out. Set the caster when you’re done. And yeah, throw on a new stabilizer too but don't post about that on the internet… you will just get crushed.
Review List for worn parts. Click links to learn how to inspect:
- Tie Rod ends
- Drag link ends
- Pitman Arm
- Ball Joints
- Wheel/Unit bearings
- Track Bar Bushings
- Steering Knuckles
- Control Arm Bushings
Caster:
Often the root cause, watch the caster angle closely. The pinion angle of the axle in the front is generally less critical than the rear so focus on the steering geometry as the primary concern. Likely reducing caster to some lower single digit numbers (around 4.25 on Jeeps with coil suspension systems) will make a tremendous difference. This can be difficult to do as alignment shops look up factory specs and policies do not allow them to set the caster outside of those parameters. This is important to know because factory setting may not fix the problem. Simply getting an alignment at Bobs Tire and Wheel won’t make it better.
When your ride decides to let it fly, slow down. It will be your natural reaction anyway. Once the frequency changes enough, the shaking will stop. Now go swap out some parts and adjust a few things. Death Wobble certainly isn’t a reason to stop loving your rig. You keep your mate despite the tantrum right? I mean… Right.?