I see that Stellantis is finally settling over the Jeep death wobble..

[5030]

The more joints, the more slop, the more wobble.

 

[2LaneCruzer]

Older cars had what they call king pins (before ball joints) that would cause wobble when worn. My old 1930 Chevy would sometimes dance all over the highway. Of course, it was never driven fast at all.

 

[zzvyb6]

Here's THE explanation of this form of what has been called 'shimmy' long before many of you were born. Keep in mind, I have over 40 years of automotive engineering in the Vehicle Dynamics realm, and have even worked on hybrid specialty vehicles (limosines) that you might see on TV in National News reports that needed this problem addressed.

'Shimmy' is the unintended result of coupling between vertical wheel movement and wheel steer movement (not steering wheel movement). The root cause is non-zero angle on the single or double tierod(s) connecting the Pitman arm to the tie rod connection(s). If the tierods are not horizontal in the front view, your front suspension is susceptible to shimmy. A vertical wheel displacement (bump or pothole or tire imbalance) excites lateral forces in the steered wheels mechanism. Much like an inverted pendulum, the oscillation grows because of positive feedback from the steer mode to the vertical mode of wheel travel. Like any pendulum system (hinged from the top or bottom, techniques to reduce or eliminate it involved damping from either friction (new suspension parts) or dampers (steering shock absorbers), or removal of the coupling factor. Obviously lift kits that do not re-align the Pitman arm are principle players. 'Bulldozed' springs which lower the body also are involved. Bulldozed springs are deformed (as in bent) usually from overloading due to many situations. This aggravates the coupling term. Additionally, vehicles with power steering can have worse shimmy because the flow valve in the steering gear will respond to the increased tierod loads in an attempt to reduce them, but with a phase delay that actually increases the forces. Worn steering system parts (lower friction), worn-out pump, lower rack&pinion slipper bearing friction, valve leakage, play in ball joints all add up to create the shimmy phenomenon.

Tires are also players because the air pressure, tread width, wheel rim width and sidewall stiffness of the tire carcass affect the steered stiffness of the tire (called self-aligning torque stiffness). So tire brand, wheels and pressure are ways to reduce the problem or make it worse. Sure, steer dampers help to reduce the amplitude of the shimmy, but eventually these parts wear out or get damaged from the high forces and soon the problem returns. But the root cause is the positive feedback in the steering mechanism.

Note that many of these trucks have symmetric ride steer. (both wheel turn the same way when the front end rises. In most vehicles with purely independent suspensions, the wheels turn in opposite directions when you raise the front end up. (called ride-toe or bump steer). This parallel steering design also feeds the problem because both tires scrub the same way instead of one tire cancelling out the other's steering resistance moment. Note that many different Pitman arm drop dimensions are available from truck specialty shops which correct the geometry factor of this problem. Steering gear stays put, steer arm ball height is altered as installed. But the loss of friction from wear/mileage is always going to aggravate the situation. Plus, soft springs means lots of wheel travel, so the Pitman arm can't always be horizontal.

Now you know the reason(s), many science projects and technical papers written about the subject, but the lore from owners with 'feelings' instead of facts & data permeates the web.

 

[Rustyiron]

I've experienced it ever since my 1st vehicle (74? CJ 5 with 304? v8) as a kid. Might have had something to do with the longer spring shackles and the 12x15 tires and the other monkeying around with the suspension. I learned very early not to be alarmed.
My "lift kit" matched my cherry bomb dual exhaust perfectly , oh the good dumb azzkid memories.

 

[5030]

My 350 is 6 over stock but I modded the suspension to accept that. Did a front axle flip on the front as well. Now that I'm old, I wish I didn't. Hard as hell to get into and out of. I might add that doing an axle flip is no easy matter, you have to be a good fabricator to accomplish it as it entails extensive welding. I did mine because I wanted a high portal front axle for clearaance. I also added an ARB air locker and a Tru Trak out back. and all my springs are running on greaseable Thompson linear roller bearings. In fact, every joint is greaseable including all the U joints. No death wobble on my 350. It's always tight and well greased. I run 36 x 10.50's MT mudders too on Alcoa forged aluminum wheels.

I did have to change the steering box mounts as the huck bolted mounts weren't up to the task. I welded up bolster mounts and drilled and tapped them for A325 high strength bolts.

Would I do it again? Nope.

 

[5030]

Of course it still rides like a lumberwagon unless it has at least a ton in the bed...,

 

[zzvyb6]

I have a proposal for any of you who can create this shimmy at any time they choose. I want to know if your problem is geometry or power steering caused. Yes you need to be equipped with power steering.
When it starts to dance, shift into neutral and floor the throttle. If available steering pressure is low because you got off the gas AND the pump is worn, then you could get the wobble to stop because now the power steering valve has more 'authority' due to the engine rpm increase.
You can also try to shut the engine off when it happens (don't let the steering lock up on you, crashing is not an option). If this works, the worn steering gear is actually the cause, with the engine off, no steering oil pressure, the valve feedback is disabled, and the blocked steering lines add a huge amount of damping.

Just a science project, but could help a LOT of folks here. One would be good enough for me.

 

[ovrszd]

I have a proposal for any of you who can create this shimmy at any time they choose. I want to know if your problem is geometry or power steering caused. Yes you need to be equipped with power steering.
When it starts to dance, shift into neutral and floor the throttle. If available steering pressure is low because you got off the gas AND the pump is worn, then you could get the wobble to stop because now the power steering valve has more 'authority' due to the engine rpm increase.
You can also try to shut the engine off when it happens (don't let the steering lock up on you, crashing is not an option). If this works, the worn steering gear is actually the cause, with the engine off, no steering oil pressure, the valve feedback is disabled, and the blocked steering lines add a huge amount of damping.

Just a science project, but could help a LOT of folks here. One would be good enough for me.

Not even close.

Readers, do not shutoff your engine going down the road during death wobble or any other time!!!!

 

[shooterdon]

I had it happen on my first and only Jeep. Bought it used about 6 years ago and traded it on an F150. The shop I took it to had no clue what to do. They wanted to start changing out parts Was not going to deal with it.

 

[5030]

Little backstory on FCA (and Stellantis). I retired from rhe outfit that supplied under sheetmetal components to them, actually over 85% and they would buy anything so long as it was cheap, cheaper the better. Never cared abour chems or certs either. Best thing they did was loose the Torqueflite and their gas motors. The Cummins and the Asian were good moves but the running gear is still junk and always will be and that includes the Jeeps.

If it's cheap, they buy it.

Good example are the valve rockers. Outfit south of Toledo heat treats all of them and makes them workable. Why they have issues with the valve trains on their gas motors. Junk.

 

[riptides]

I think some of you have seriously NOT had the Death Wobble experience.

It's called Death Wobble for a reason.

 

[ovrszd]

Good example are the valve rockers. Outfit south of Toledo heat treats all of them and makes them workable. Why they have issues with the valve trains on their gas motors. Junk.

The 4.0L I6 used in Jeeps until '07 is, if not #1, at least in the top three, most reliable gas engine used. I've only saw two have major issues. 1st was a head gasket because it was ran without coolant. 2nd was a broken rod, engine in the stutter box for at least 90 seconds.

 

[2LaneCruzer]

A bit off topic, but I'm wondering if anyone else has experienced this phenomenon: I was driving my '70 Nova, turned off the main highway onto an exit that had an immediate sharp turn. The turn happened to have a fairly long stretch of washboard ridges on it, and I was driving at a pretty good clip...the front end started bouncing so badly that I was clear off the road and nearly in the ditch when I finally got the car under control.

 

[ruffdog]

A bit off topic, but I'm wondering if anyone else has experienced this phenomenon: I was driving my '70 Nova, turned off the main highway onto an exit that had an immediate sharp turn. The turn happened to have a fairly long stretch of washboard ridges on it, and I was driving at a pretty good clip...the front end started bouncing so badly that I was clear off the road and nearly in the ditch when I finally got the car under control.

Bad shocks.........

 

[Oaktree]

The 4.0L I6 used in Jeeps until '07 is, if not #1, at least in the top three, most reliable gas engine used. I've only saw two have major issues. 1st was a head gasket because it was ran without coolant. 2nd was a broken rod, engine in the stutter box for at least 90 seconds.

The slant 6 and 318-derived engines were right up there too. Couldn't kill 'em.
Dunno about their more modern engines. I've read bad things about their 3.7/4.7 engines, but I have one of each, both approaching 200k and no issues other than the soft exhaust manifold bolts (4.7 only).

 

[Dftodd]

I think some of you have seriously NOT had the Death Wobble experience.

It's called Death Wobble for a reason.

I experience it once in an f250 regular cab diesel. Highway department was adding a second lane on a merge lane from one interstate to another. Hit some bumps and I thought the front end was coming apart.

Think my bottom sucked up half the drivers seat.

Steering wheel was slamming back and forth. And the front end felt like it was hopping. Let off the throttle and road it out going around that corning. Front end settled down at around 35mph and then I was able to speed back up to highway speeds.

 

[deserteagle71]

The 4.0L I6 used in Jeeps until '07 is, if not #1, at least in the top three, most reliable gas engine used.

^This.

When I heard that Jeep was going to a V6 in 2007 I made sure to get a 2006 Rubicon which I still have. Been driving Jeeps with that I-6 for almost 30 years now and never had any engine problems with any of them.

Jeep is going back to the I-6...already available in the new Wagoneer and Grand Wagoneer and I'm sure will be in the Wrangler before too long. But the new I-6 will be only 3 litres and have two turbos, so we'll just have to wait and see how dependable it turns out to be.

 

[Bearsixty7]

I never had it on my 2002 F250.

My old 2006 F350 developed the DW well after warranty expired. A local Shop replaced tie rod ends and a few other steering components to fix it. There was a short bridge just a couple miles away I crossed to and from work that would always trigger it, once it was repaired, it never did it again.

Just a week ago we were coming back from Jeeping so we had the TJ on the trailer of our 2019 F350. We hit some really bad pot holes on Hwy 82 going east and it started the DW the worse I have ever experienced! I had to slow down to about 25mph before it stopped. Truck only has 35K miles on it. It will be going to the Dealer next week. I already have a Tech bulletin on the steering stabilizer but that is never the fix, only a bandaid. Hopefully they will find the real issue without hassle.

 

[ovrszd]

I experience it once in an f250 regular cab diesel. Highway department was adding a second lane on a merge lane from one interstate to another. Hit some bumps and I thought the front end was coming apart.

Think my bottom sucked up half the drivers seat.

Steering wheel was slamming back and forth. And the front end felt like it was hopping. Let off the throttle and road it out going around that corning. Front end settled down at around 35mph and then I was able to speed back up to highway speeds.

I've saw other vehicles experience it. Front tires are jumping completely off the pavement!!!

 

[Dftodd]

I've saw other vehicles experience it. Front tires are jumping completely off the pavement!!!

That's what it felt like. I was in a turn at around 60mph at the time, too. Scared the daylights out of me. Thankfully, I was able to coast it out.