New Gladiator DW and a Possible Solution?

[Artsifrtsi]

The only problem with the logic in the parts being an issue, is those parts are potentially a facilitator, rather than the initiator of issue. Something must be the initiator to the DW, such as an out of balance tire. The Track bar (as an example) could be loose, whether not torqued properly or has bad end/s, and that looseness will allow the vibrations to amplify and oscillate into the DW. Driving down the road, and even hitting a bump, the steering system parts really only move in very small planes which could never initiate the issue.

Now, all that said... the only time my TJ had a DW incident, I replaced the shocks, and found that the drivers front shock had completely failed... to the point I could compress and expand it in my hands really quickly, and collapsed it would never push itself back out. This introduced the oscillations needed to kick off the DW event.

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[tmgarmon]

The only problem with the logic in the parts being an issue, is those parts are potentially a facilitator, rather than the initiator of issue. Something must be the initiator to the DW, such as an out of balance tire. The Track bar (as an example) could be loose, whether not torqued properly or has bad end/s, and that looseness will allow the vibrations to amplify and oscillate into the DW. Driving down the road, and even hitting a bump, the steering system parts really only move in very small planes which could never initiate the issue.

Now, all that said... the only time my TJ had a DW incident, I replaced the shocks, and found that the drivers front shock had completely failed... to the point I could compress and expand it in my hands really quickly, and collapsed it would never push itself back out. This introduced the oscillations needed to kick off the DW event.

Well said. I really think that the initiator is the tires. The rest comes down to the assembled components ability to compensate on those planes, which is what a stabilizer does if above or below it is rigid. The thought is, that since I've tried two different stabilizers, the Roadmaster Exact Center, which put 110# of equal force on both sides of the Tie rod, and the Factory one, which puts out zero force until moved, gave the same result. The reaction (flex) is either above or below it. Since the Jeep does not have DW when at stock height, but does when lifted, what changed? The planes of movement above, not below. So time to look at those planes and see what can move.

Since the axle end of the track bar is still essentially the same, it has to be the other end.

I'm rambling......and it's all theory. I'll give you an update and let you know if I'm full of s**t

Edit......Both ends of the Track Bar plane changed. But the fulcrum each end acts against is different. It's essentially zero on the axle end, and whatever the length of the frame mount side is on the frame end.

More rambling.......

 

[ShadowsPapa]

No - don't think of it a a part being the initiator - that's also flawed logic. The parts are unable to prevent the oscillations or wobble/extreme shimmy.
The initiator is the bump or crack, the "bump steer" that starts things.

The broken shock wasn't initiating anything- but it wasn't preventing the reaction, either.
What initiated things was a bump - the shock could not halt the oscillations.
There was an event that initiated things. That event was hitting a bump or hole or crack or joint on the road/bridge.

Here is one explanation (there can be multiple causes or reasons) - when things flex, geometry is changed, etc. -

In a very real way, our big heavy tires are gyroscopes (even tops).......... Look at what happens when the rotation is either sped up or slowed down - what the gyroscope does. No one is touching the axis the gyroscope itself is on, only speeding or slowing it's rotational movement on the horizontal plane.

 

[tmgarmon]

The initiator is the bump or crack, the "bump steer" that starts things....................

In a very real way, our big heavy tires are gyroscopes (even tops)..........

I do stand corrected, the 'initiator' is most definetly the bump or crack. Just like your failed shock, I feel that the tires aren't helping to prevent the reaction, this is the reason that a lower air pressure is often run to help dampen the reaction to the crack or bump.

So.....OK. Got this Bad Boy mounted in there last night along with retorquing all the ball joints and TRE's, and going to the next slot on the castle nuts. Work is getting in the way, so no opportunity to see if these have done anything for the DW. I'll let you guys know........

 

[Artsifrtsi]

The broken shock wasn't initiating anything- but it wasn't preventing the reaction, either.
What initiated things was a bump - the shock could not halt the oscillations.
There was an event that initiated things. That event was hitting a bump or hole or crack or joint on the road/bridge.

Road surface is the trigger. The oscillations are still caused by the moving part, and amplified through the entire system with the output being "Death-wobble". The road surface will not create the unbalanced condition, it will only trigger the event.

I do stand corrected, the 'initiator' is most definetly the bump or crack. Just like your failed shock, I feel that the tires aren't helping to prevent the reaction, this is the reason that a lower air pressure is often run to help dampen the reaction to the crack or bump.

So.....OK. Got this Bad Boy mounted in there last night along with retorquing all the ball joints and TRE's, and going to the next slot on the castle nuts. Work is getting in the way, so no opportunity to see if these have done anything for the DW. I'll let you guys know........

I look forward to your results.

 

[ShadowsPapa]

Road surface is the trigger. The oscillations are still caused by the moving part, and amplified through the entire system with the output being "Death-wobble". The road surface will not create the unbalanced condition, it will only trigger the event.



I look forward to your results.

Pretty much what I said.
It also doesn't have to be an unbalanced condition unless you are using the term to refer to things like geometry, stresses, crappy mods, or changes that unbalance how things work.

 

[tmgarmon]

Pretty much what I said.
It also doesn't have to be an unbalanced condition unless you are using the term to refer to things like geometry, stresses, crappy mods, or changes that unbalance how things work.

More like exactly what you said..............
I'll update this weekend and let you know.

 

[tmgarmon]

Well, time for another update. Took the Jeep out for a drive Saturday. DW was still poking fun at me. Particularly at the freeway expansion joints that I could make do it every time. One of the guys at my Jeep club offered me his services to help diagnose the issue. I figured, "What else haven't I tried before we proceed to tear into it one more time?" All I could think of was tires. So I bit the bullet and bought a set of 2021 JL Rubi takeoffs yesterday. We weren't meeting until noon, so I picked them up, threw those suckeres on and took it for a drive......Lo and behold, no more DW! I tried to get it to do it! Then I went to my Jeep buddy's house. He tried to get it to do it......It's magically gone! Are the new tires masking another problem? Fingers crossed, but I don't think so. I drove the Jeep over every spot that had induced DW before and it was stable. My confidence level is still pretty low, which hopefully will improve with more miles.

 

[Artsifrtsi]

I'm glad it appears as simple as the tires are fixing it for you!

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