Help diagnosing death wobble on 2004 Wrangler

[mrblaine]

In order to help understand what is going on, one needs to look up precession as it relates to a gyroscope and watch some videos of it. Then spend some time and imagine just how much force is imparted against the steering and control links to prevent wobble based precession. Now take two of those gyros that are trying to do the precession thing and put one of them out of balance, then both of them. The amount of force generated is astounding.

 

[Paul Ruggles]

It is less susceptible since it has the inverted Y link steering or Haltenberger linkage style steering. But you got it with the mods. There are very few instances of stock rigs with DW. It is only when we start changing stuff up and then asking the parts designed to handle smaller tires to do the job of much bigger parts that we start seeing issues.

The biggest problem with DW is all the repeated myths and fallacies. Very few actually understand that if a "solution" is offered up as a cure, then the opposite should also induce DW and that very rarely holds true. If more caster is the answer, then all rigs with less caster should have DW and they don't.

If toe out solves it, then all rigs with toe in should have DW and they don't.

If flattened angle steering is the answer, then all rigs without a drop pitman and a drop trackbar bracket should have DW and they don't.

If hole size versus fastener diameter is the answer, then no rig should be free of DW. There are no zero fit holes in the control links except the steering TRE's and one end of the front trackbar. The rest are sloppy fit holes with undersize fasteners.

Each case has to be diagnosed and then repaired but of utmost important is good tires kept balanced and true. That isn't a guarantee that you won't get DW, but if you don't have good tires, then your chances of diagnosing the issue go way down.


There are lots of cases of non Jeep DW out there. Just have to look for them.

 

[Paul Ruggles]

Whoops, hit post reply before I replied. Another vehicle with death wobble issues is the 1994 to 2003? Dodge ram. There are numerous 'fixes'for those trucks out there, just like 'fixes' for coil spring jeeps.

 

[JEEPCJTJ]

Whoops, hit post reply before I replied. Another vehicle with death wobble issues is the 1994 to 2003? Dodge ram. There are numerous 'fixes'for those trucks out there, just like 'fixes' for coil spring jeeps.

Throwing money and hoping for the best.

The guy that owns the shop where I take anything I can't handle was a mechanic for one of the Dodge dealers that were put out of business by our fine government 10 years ago.

The DW was only on the 2500 and larger trucks which had the solid axle, coil spring front end. Chrysler sent engineers out to every dealer to train everyone what the problem was and how to fix it.

According to them the problem was the negative scrub radius caused by the (way too) positive wheel offset.
(I wish these pictures both faced the same direction)



The factory repair was dealer installed wheel spacers to take the scrub radius to zero, or maybe close to it I'm not sure.

On my TJ I put in a new track bar then got a near perfect alignment and the tires rebalanced by this shop. At that point he DW only showed up when hitting about 75% of the same places that caused it before. The wheels were a negative offset which caused a positive scrub radius, the opposite of the Ram.

Then I found some original Rubicon Moab wheels and have been DW free for 16 months. I have had some unbalanced tires due to mud build up. At first I thought I was bringing DW back but just speeding up would stop that vibration and cleaning the mud off took care of that.

 

[mrblaine]

Throwing money and hoping for the best.

The guy that owns the shop where I take anything I can't handle was a mechanic for one of the Dodge dealers that were put out of business by our fine government 10 years ago.

The DW was only on the 2500 and larger trucks which had the solid axle, coil spring front end. Chrysler sent engineers out to every dealer to train everyone what the problem was and how to fix it.

According to them the problem was the negative scrub radius caused by the (way too) positive wheel offset.
(I wish these pictures both faced the same direction)
View attachment 117090
View attachment 117091

The factory repair was dealer installed wheel spacers to take the scrub radius to zero, or maybe close to it I'm not sure.

On my TJ I put in a new track bar then got a near perfect alignment and the tires rebalanced by this shop. At that point he DW only showed up when hitting about 75% of the same places that caused it before. The wheels were a negative offset which caused a positive scrub radius, the opposite of the Ram.

Then I found some original Rubicon Moab wheels and have been DW free for 16 months. I have had some unbalanced tires due to mud build up. At first I thought I was bringing DW back but just speeding up would stop that vibration and cleaning the mud off took care of that.

And again, if zero offset wheels fixed DW, all Jeeps without them would have DW and they don't. In fact I know of several running effective back spacing of 2-3" with no DW.

 

[JEEPCJTJ]

My "Throwing money and hoping for the best. " comment was regarding parts changers in general which seem to be what too many people do try to fix DW.

The part about the shop owner's Chrysler training was just about what they taught him and others about the Ram DW.

I wasn't posting what I did as being the only way it can or needs to be done, I just wanted to show what didn't work on mine and what did work. The part that did work was very similar but in the opposite direction to what Chrysler did on the Rams.

And again, if zero offset wheels fixed DW, all Jeeps without them would have DW and they don't. In fact I know of several running effective back spacing of 2-3" with no DW.

I don't even know what my offset or back spacing is but any change in those effects the scrub radius. I'm just back to original wheels (with new tires) instead of the less back space and wider wheels I had when DW was there.

 

[Shawn B]

So I have an update. The toe out test resulted in no difference in the onset or severity of the wobble. I installed the Rough Country forged track bar with their updated design drop bracket. We realigned the Jeep and with the adjustable track bar I can now get the thrust angle to zero. Took it for a test drive and still no difference. The wobble starts at 55 mph after hitting a bump and will not stop until I come to a complete stop. Next I removed my 4 year old 3,000 mile Rough Country steering stabilizer which came new with my lift kit. I replaced it with a new Rancho 9000 stabilizer and the wobble is gone for the 1st time in 2 months. I then took it on a longer test drive and the steering isn't 100% but its now a vehicle that can go down the road safely.

For those who have experienced a Jeep death wobble you know it doesn't go from smooth to the full wobble instantly. Once you hit the slight bump at highway speeds the wobble quickly builds into the full wobble over a period of about 3 to 5 seconds. My point is before the wobble is at its worst you can tell when its about to come on with the fast slight shake. ****It still has its slight shake you feel just as it did before today it just isn't going into the extreme wobble. The shake feeling is slight now.

Yes, I know the steering stabilizer can't cause the wobble and installing a "better" stabilizer is not fixing any problem but simply masking the unresolved issue.......... I know

What we have done so far over the last month or so is:
2 sets of all 4 ball joints landing on the Spicer OE joints
4 track bars including the RC forged with new bracket done today
3 sets of all tie rods / drag link
Balanced tires many times accurately
Completely new tires
Back to my other tires
New axle joints
Upper control arms OE style
Taken things apart to look for oblonged mounting holes
Retorqured bolts many times
Looked for broken welds, cracks, or fractures in any metal
**Then realigned too many times to count trying all different caster settings from 5 to as much as 7.9 (now at 6.4) while toe camber, steer ahead, and thrust angle all in spec. Thrust angle is now at zero.

I feel confident I have ruled out tires as the issue. All that I have not addressed is the RC 4" lift kit lower control arms which seem to be very tight, I have not replaced the steering gear, I have not replaced the upper control arm bushings at the axle end, and I have not replaced any shocks yet.

Maybe now i just leave well enough alone? I can say that after driving for the last 4 years with this lift in the Jeep, the slight shake I feel now after replacing the stabilizer wasn't there before all of this started. Its was smooth down the highway..... But it isn't that bad

 

[g.hayduke]

Sorry if I missed this but I did not see where you tried removing the trackbar drop bracket and dropped pitman arm?

It seems like hardly anyone runs with those and I personally don't trust bolt-on trackbar brackets, especially since they seem to be unnecessary on the huge majority of (maybe all?) rigs.

 

[Shawn B]

Sorry if I missed this but I did not see where you tried removing the trackbar drop bracket and dropped pitman arm?

It seems like hardly anyone runs with those and I personally don't trust bolt-on trackbar brackets, especially since they seem to be unnecessary on the huge majority of (maybe all?) rigs.

I'm not sure the new RC forged track bar will fit the OE frame track bar mount?

 

[AndyG]

I'm not sure the new RC forged track bar will fit the OE frame track bar mount?

I don’t think mine will, it’s turned 90 degrees.

Has anyone seen hub unit bearings play into death wobble? Just asking.

 

[Titus1531]

Could your upper track bar bolt hole gotten wallowed out where it connects to the frame? Last time I got death wobble was when my upper track bar bolt was loose...

That's what it was for me too. I just cranked it down and mine went away instantly.