Scary death wobble

[Paddletrucker]

So...I've experienced death wobble. Once in my pickup. It was pretty mild, and I was doing 30 or so on a back road. No biggie. Fixed it right up. One night, it happened to me in a semi, pulling three trailers. The shimmy itself wasn't too bad, but being close to 100,000lbs, 90 feet long, and pulling three trailers made it a lot worse. A healthy dose of brakes and it was over with nothing more than a sick feeling in my gut and some shaky legs.

Today, though, I was on I-35 in downtown Kansas city in afternoon traffic pulling doubles and a lifted ZJ (a nice one) with a really cool front bumper and winch, appeared in my left side mirror coming up fast. Noticing it was a jeep ZJ lifted 4 or 5 inches, I wanted a better look. I watched as he gained on me in the traffic.

He passed me, and went to change lanes in front of me, from left to right. That's when it happened. The most violent looking thing I'd ever seen. He all but completely lost control. He took an exit, although I'm not sure if he was trying to. The wobble was unbelievable. It caused him to fish tail. I could see that he couldn't even keep his hands on the steering wheel. It continued until he slowed to a crawl. When it's happened to me, I've been able to stop it by reducing my speed by half or so. This guy had to almost stop completely.

The speed limit there was 45, I was going a touch slower, but he was probably doing close to 60 when he passed me and the death wobble started. I'm glad he got it shut down without an accident. I got a really good look, since I dove my brakes from 45 to avoid him.

Man, I DON'T EVER want to experience that in my Jeep!!

[cantab27]

7440



yeah ya gotta drive through that death wobble shit ...:D

[4.3LXJ]

Yeah, DW can be a real waker upper. No napping afterwards. It is one reason auto manufacturers like to move to independent front suspensions. I had it in a 68 CJ5 due to a loose bell crank. Changed that out right away for something more modern. Had in my XJ and finally solved it with bomb proof stuff

[drakan1908]

I run 70 or 80 in my ZJ all the time. I'm lifted 4 inches on 31's. But like 4.3 said I used the good stuff. :D

[rabies]

is there such thing as fixing death wobble on el jeepo?
im almost ready to give up on it

[nickyg]

is there such thing as fixing death wobble on el jeepo?
im almost ready to give up on it

Yes you can fix it. Tracking it down is the hard part. the last time I got it it was the left upper ball joint.
The front suspension on a xj is like a house of cards. Evreything must remain in perfect balance.

[Mudderoy]

So...I've experienced death wobble. Once in my pickup. It was pretty mild, and I was doing 30 or so on a back road. No biggie. Fixed it right up. One night, it happened to me in a semi, pulling three trailers. The shimmy itself wasn't too bad, but being close to 100,000lbs, 90 feet long, and pulling three trailers made it a lot worse. A healthy dose of brakes and it was over with nothing more than a sick feeling in my gut and some shaky legs.

Today, though, I was on I-35 in downtown Kansas city in afternoon traffic pulling doubles and a lifted ZJ (a nice one) with a really cool front bumper and winch, appeared in my left side mirror coming up fast. Noticing it was a jeep ZJ lifted 4 or 5 inches, I wanted a better look. I watched as he gained on me in the traffic.

He passed me, and went to change lanes in front of me, from left to right. That's when it happened. The most violent looking thing I'd ever seen. He all but completely lost control. He took an exit, although I'm not sure if he was trying to. The wobble was unbelievable. It caused him to fish tail. I could see that he couldn't even keep his hands on the steering wheel. It continued until he slowed to a crawl. When it's happened to me, I've been able to stop it by reducing my speed by half or so. This guy had to almost stop completely.

The speed limit there was 45, I was going a touch slower, but he was probably doing close to 60 when he passed me and the death wobble started. I'm glad he got it shut down without an accident. I got a really good look, since I dove my brakes from 45 to avoid him.

Man, I DON'T EVER want to experience that in my Jeep!!

I wonder if his track bar broke. Did you notice if he was able to continue?

[4.3LXJ]

is there such thing as fixing death wobble on el jeepo?
im almost ready to give up on it

Yes, you can fix it. But things have to be in spec. First of all, your castor angle has to be right. Tires need to be good, no flaws and balanced properly. Then steering box needs to be tight. One thing to check which you may not have, is the hole on the axle track bar mount. They get a little egg shaped and allow the bolt to wiggle back and forth setting up the harmonics for a death wobble. It needs to be real snug in that hole, no wiggle

[Paddletrucker]

I wonder if his track bar broke. Did you notice if he was able to continue?
Yes, he continued down the access road, as he'd taken am exit. I didn't see him get back on I-35, but it winds through downtown right there. I don't THINK anything broke, but I was looking from a ways off. Just some super nasty death wobble, complete with fishtailing and I'm sure irreparable seat cushion/underpants combo

[OldFaurt]

is there such thing as fixing death wobble on el jeepo?
im almost ready to give up on it

I had a little El De Woblo on my XJ at 75 mph, Turned out to be just a bit more caster,
(helped but not quite all) then noticed my sway-bar bushings were shot to hell.
Changed those out and WOW what a difference.
Turns out that when there is free play in those bushings,
it can cause the body to roll freely in a small but amazingly reactive amount.
that small amount of free body roll causes a harmonic point that is amplified in your tie rod
from the steering box to passenger side knuckle distance.
Yeah I know what your thinking, it can't be much, right?
well, it would be like you whipping your steering wheel back & forth about 2", that's how it starts...
Then all the Rubber Bushings through out your steering system start to compress and uncompress...

Yeah, I think you can see where THAT'S going...

So here's the nerdism
As the Jeep leans to the left, it pulls that knuckle towards the driver side (Jeep turns left).
Then as the body rolls right because of the turn, the tie rod now pushes the steering towards a right turn.
Mind you this push pull is only around an 1/8 of an inch to start, but it is a positive feedback loop!
All you engineers out there know what positive control feedback does! Yikes!
So, when you are dumping all that hard earned money into Ball joints and tie rod ends...
Don't forget the $20 worth of Sway bar bushings and grommets & adjust the play in your steering box!

May the force be with you...
Not against you!