Update: See post #9..... I think that's my issue


Original Message:
You ever see a motorcycle just before a near inevitable crash go into the death wobble where the front wheel oscillated left and right way too fast for the rider to correct it? Well my 2001 Cherokee XJ will do that sometimes after hitting a bump in the road or going over a rail road crossing. I can't grab the wheel to stop it. I have to slow down to make it calm down and straighten up. What could possibly be the issue?

 

Could be a lot of things, or a combination of different suspension components.

Pull/tug/push on every ball joint and bushing down there. Get a big thick pry bar to help lever things to see if they're worn out

 

My understanding of “death wobble” is this. Somewhere in the vehicle, one or more components is worn beyond tolerances, and when oscillation initiates from a suspension “traumatic” event (hitting a bump or a pothole) or also when a vibration reaches a certain point and harmonic at a certain speed, it causes the other components to react. This is called the “multiplier effect”, where one component affects one or more other components as the event travels through the front end of the vehicle.

Death wobble is not uncommon with the XJ. It is even more common with a lifted XJ. Finding the worn component or components is not always easy. It can sometimes be downright difficult. Sometimes it’s obvious, other times everything appears to be okay when you perform an inspection on a hoist, but getting the vehicle up in the air and going over everything with a fine tough comb is always a good first step. It is very helpful if you know exactly how to perform a comprehensive inspection of every single front end part, looking for abnormal wear and or play in that hardware. If you do not know how to do this type of inspection, pay an experienced professional to do it. Be sure to ask them if they are familiar with “death wobble”, as not all technicians are versed in this…..

Check out the below link if you would like some extensive reading on “death wobble” causes and cures. From my research, Kevin (the author of this tutorial) is possibly the best in the business with tracking down root cause of death wobble. He does offer hardware for sale that can help resolve death wobble, but even if you don’t buy any parts from him, you can still get some excellent ideas on what to look at in resolving your death wobble.

http://www.kevinsoffroad.com/how-to-...-death-wobble/

Possible causes of death wobble are listed below. Isolating death wobble is a process of elimination and the root cause is not always obvious and it can often be caused by a combination of things! From my personal experience, I would first concentrate on the track bar and the control arms and associated bushings.
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-Front tires out of balance (try swapping fronts to rear; see if symptoms change)
-Tire pressure. Don’t laugh. It’s not a root cause but can exaggerate the problem. Experiment with lower tire pressure to see if it helps
-Improper lug nut torque on wheels
-Front alignment out of spec
-Loose track bar
-Worn track bar bushings
-Worn track bar (check for play!!)
-Bad control arms and associated bushings
-Worn/damaged steering stabilizer (not generally a cause in and by itself)
-Worn/damaged shocks
-Worn/damaged tie rod end
-Bad U Joint
-Bad ball joint
-Loose frame mount
-Steering box loose
-Bad front hub assembly

 

TJ is spot on here. Anything that's front suspension related, and even tires, can be the cause.
The big thick prybar will help you lever suspension pieces that you can't necessarily pull/push/tug hard enough to determine if they're worn out or not.

Whatever you do, don't just replace the steering damper and call it fixed. There's a root cause to your issues and you gotta tease it out. Sometimes it's easy, sometimes it'll be a combination of fairly worn, but usable components that results in a very unusable situation.

 

Thanks a bunch.

*I do suspect I have a bad wheel bearing due to some squeaking I used to hear. I haven't heard it in a while though and the wear is not bad enough to allow play when I try to rock the wheels while they are off the ground. I'm going to replace both fronts anyway though. *My tires are fairly worn. Though not at the wear bars yet, it's time for a replacement. *So far, I've only looked and tugged on things with an untrained eye to see if anything was bent or had play. I noticed nothing. I do have a friend with a lift and that has more suspension knowlegde, so I'll see if he's willing to help. If I can't find anything, I seek more expert advice. Thanks again.

 

Get a friend or family member to turn the steering wheel back and forth while you look at EVERY suspension and steering component.

Chances are you'll see whats moving and shouldn't.

I had my wife turn the wheel while I looked. My body side trac bar mount was moving all over. Dead give away as to what was wrong. Replaced it, not a problem since.

 

So it seems the main source of my problem is the drag link, particularly at the ball joint where it attaches to the pitman arm.

Can I replace just this end? When I look for the drag link end, I keep running into tierod ends, but their descriptions do not specify compatibility to the drag link. Also, what are the chances that the pitman arm is also damaged at that joint?

 

Where the drag link attaches to the knuckle is probably trashed too. Replace the drag link and pitman arm, isn't your life worth $150?

 

Well, there was a bit of issue with the drag link. The pitman looked fine, but I replaced both. Then the problem got more frequent . So I reassessed and saw the track bar was shifting left and right. While I was there, I checked for movement. I say nothing else. This inspection, according to videos, would cover 95% of the potential problem areas. So I installed a new track bar. It then got WAY more frequent. Obviously, fixing the small movement issues allowed the real issue to be more apparent. I then decided to look for a couple places to mount a GoPro camera to see the wobble happen, while there, I noticed this.....



The bolt is not even close to being centered and the bushing simply looks trashed. The others are all centered, but also not very pretty. I decided not do the camera thing. Looks like a full LCA or bushing replacement is in order.

 

Good catch! Make sure when you put the in the you tighten the bolts up with the vehicle on the ground. Don't tighten them up with it jacked up on stands or you will trash the new bushings as well. Vehicle on the ground and level, then tighten the bolts.

Black89

 

Thanks for the tip.

I haven't searched for the how-to yet, but I assume I should support the chassis at normal ride height with jack/jack stands then remove and replace one arm, then r&r the other arm, remove the jack/stands, then tighten the bolts.