Cold weather = Death wobble

[ShadowsPapa]

Wench = hooker ≠ winch

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[ShadowsPapa]

Front end is going to be "sloppy" no matter what, compared to most modern mainstream vehicles, other than ford super duties and ram 2500s and up. A solid axle vehicle just doesn't handle the same as an IFS vehicle.

Yes and no -
It won't handle as well, but looseness, slop - no excuses.
A solid axle vehicle and handle very well.
The issue is that today's IFS is rack and pinion in many cases - and it's a quick ratio steering.
My wife's GC steering - I hate it. You sneeze and you change lanes. Move that wheel 1" and you think it's going to do a 180 on you. It's stupid quick ratio. Maybe great for executives, attorneys, women, older people, whatever, but not for anyone who has driven trucks and cars of all types over the years.
The ZJ and WJ are solid axle and those handle great! Tight, good maneuverability, corner well, etc.
There should be no slop in these. Even the service writer at the dealership that replaced my 2020's steering gear made a comment "these should not do that".
My 2022 is tight. Move the wheel any and it's responding. It's not "quick ratio" but then it's longer than some vehicles. The steering ratio used to be determined by wheelbase, and other factors - such as a Camaro getting quick-ratio steering gear compared to other similar cars.
It's really not fully a matter of the solid axle as the solid axle only has an effect on uneven roads, tight curves where the vehicle leans and so on. Highway driving you really shouldn't feel a difference.
Heck, my friend and neighbor (who is running the front brakes, spindles and hubs from my 73 Javelin under his Ford) takes his 49 Ford to the salt flats and runs it. He drives it all around the country. It's not exactly IFS............

 

[Dougstdig]

I get a low level steering wheel shimmy around 35 MPH on rougher than normal roads.
After driving for about 5 minutes it is gone.

Part of that is low air pressure in tires from cold, part of it is the cold steel in the steering. Once everything warms up it is gone.

I don’t think this has anything to do with cold steal in the steering.

When tires sit motionless with a load they have a tendency to “flat spot”. Colder weather exacerbates this. Typically, driving 5-10 miles warms up the tire and corrects the issue. Older super swampers would experience this at summer temps…and it was one of their drawbacks.

 

[ShadowsPapa]

My JT feels tight. I can almost flick it around like my Nismo. It's stable all the way up to where the speed limiter kicks in.

I've had mine up to 95 and backed down. They do watch the interstates around here......... mandatory loss of license at more than 20 over.
Mine is stable and tight. No shimmy, no wobble, no vibrations, no problems.

 

[ShadowsPapa]

I don’t think this has anything to do with cold steal in the steering.

When tires sit motionless with a load they have a tendency to “flat spot”. Colder weather exacerbates this. Typically, driving 5-10 miles warms up the tire and corrects the issue. Older super swampers would experience this at summer temps…and it was one of their drawbacks.

Cold steel won't be a cause........ cold shocks, cold other components, maybe - but the fact that the steel of the bars and tie rods - naw.

 

[jeepwaver]

i only have 5800 miles and its only three months. I am taking it in today. this feels unsafe. this is very documented issue. I am surprised there isn't a TSB for that.

 

[ShadowsPapa]

i only have 5800 miles and its only three months. I am taking it in today. this feels unsafe. this is very documented issue. I am surprised there isn't a TSB for that.

It's not that common - it's more amplified by the internet. It's like visiting a hospital then claiming all humans have cancer or are otherwise sick.

A TSB for what? There are multiple causes. Sometimes people do it to themselves with wheel and tire swaps, never thinking of what they are screwing with, all in the effort to make it look impressive to the manly set who believe wider and bigger are better, needed or not.
People throw parts at these and then wonder what went wrong.
In the less common "100% stock" examples, it's not always the same CAUSE. It can be caused by worn parts, damaged parts, loose parts, unbalanced tires or tires with other problems and more.
So what do you do? DW on Joe's Gladiator may have a very different cause than DW on Sam's Gladiator.
Too much caster can cause "caster wobble" which is basically a "death wobble". Changing tire height, wheels further out, spacers, can cause it. (so don't blame Jeep if your manly huge tires and wheels sticking way out may be involved with your DW)
People assume they know about toe and seem to like certain numbers regardless of tire size - but that's a bad idea. Similar for caster - the internet "wisdom" (and I use that term mockingly) says "more caster is better!" and that's bunk as well.

Yeah, very well documented because when it does happen - it's a major thing, but in the grand scheme of things, the numbers aren't that high unless you buy into the theory that if it's posted on the web 20 times, it's all vehicles on the road.

And it's been a thing with OTHER makes, including FORD, since at least the early 1960s - this is a thing where you need to deal with each individual case, not assume.
I've had two Gladiators -neither had so much as a vibration at all.
Grand Cherokees were solid axle prior to the WK series, no problems there.


----------------------
Here's a quote from a well-known performance guy -


the "Jeep death wobble" is basically a shimmy, and can affect any suspension with a continuous tie rod (which nearly all solid axles have) to connect the front wheels. He noted, "Shimmy is normally cause by aftermarket application of larger tires, lifts that change the front axle setting for toe, or caster and camber, or worn or damaged parts. An out of balance tire, a broken tire cord, a bent wheel, or worn shocks can be the cause."

Shimmy can be caused by wear or damage to the tie-rod ends, steering box, steering arm ends, or steering stabilizer; even an improper alignment can do it. A major cause is improper toe-in or toe-out, with oversized tires.

Most shimmys come in certain speed ranges, and some are severe enough to require coming to a complete stop. They can be scary to the first timer who is not expecting such violent behavior after hitting a pot hole or railroad track, or just hitting a certain speed.

These shimmies have little to do with design flaws, until design parameters are tampered with, or damaged. It's been around since at least the 1950s, and is not limited to Jeeps.

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So, a TSB for what?

A TSB is for a known issue that has a known fix. It's a "if this happens, do this". It's not a "try 100 things and keep trying until you figure it out".
A TSB is a service bulletin for a known - with known causes and defined known repairs. If this is broken or malfunctioning, replace this part.
Don't look for a TSB.

 

[jeepwaver]

call it what you want --- shimmy or dw - it is not normal. i dropped the car at the dealership.

 

[ShadowsPapa]

call it what you want --- shimmy or dw - it is not normal. i dropped the car at the dealership.

No one said or suggested it wasn't normal. But some logic - and facts, please!
I guess you didn't comprehend the post or all of the other stuff I, and others, have posted about it. DW is a "shimmy" - albeit a violent one. So what can cause a "shimmy" can lead to the violent shimmy known as "death wobble".
No, it's not normal, but there's more bullshit out there about it than fact. All of the youtube experts and engineer think it's a Jeep thing or recent or unique or has one single cause. FACT - this has been an issue for decades! Ford, Jeep and others - nothing new or unique, and it's not "a Jeep thing".

 

[jeepwaver]

No one said or suggested it wasn't normal. But some logic - and facts, please!
I guess you didn't comprehend the post or all of the other stuff I, and others, have posted about it. DW is a "shimmy" - albeit a violent one. So what can cause a "shimmy" can lead to the violent shimmy known as "death wobble".
No, it's not normal, but there's more bullshit out there about it than fact. All of the youtube experts and engineer think it's a Jeep thing or recent or unique or has one single cause. FACT - this has been an issue for decades! Ford, Jeep and others - nothing new or unique, and it's not "a Jeep thing".

i agree. that why i left the speculation to the internet and took the trucks to the dealership at the shop. now waiting to hear back.

also, i know most jeep owners are self-reliant and do it themselves type but personally this is main vehicle and major investment. I do not want to fix this myself. I want a working reliable and safe vehicle.

 

[ShadowsPapa]

i agree. that why i left the speculation to the internet and took the trucks to the dealership at the shop. now waiting to hear back.

also, i know most jeep owners are self-reliant and do it themselves type but personally this is main vehicle and major investment. I do not want to fix this myself. I want a working reliable and safe vehicle.

Very well said and thought out

 

[jeepwaver]

ironically, when I was there the service advisor was entering "steering stablizer issue" into the system;

 

[ShadowsPapa]

ironically, when I was there the service advisor was entering "steering stablizer issue" into the system;

That's Chrysler's standard answer to any steering instability.... sad. At least it's there and they didn't push you back out the door ignoring you.

 

[HankB]

I have read this whole thread. Interesting stuff. It is pity we don’t have a resident acoustic engineer. We have two topics going here: the original complaint about cold weather start up vibration, and the infamous DW,
AKA ”Death Wobble”.

Let me deal with the first since i can speak from professional and personal knowledge. The OP is driving on cold tires that have formed a temporary flat spot. Tire rolls around a bit warms up, flat spot flexes out, problem solved. This happens to all tires, some worse than others. It happens to truck tires and it happens to tires on go fast cars.

While I have never experienced a jeep with DW, I have experienced something similar with other cars, but usually after having messed around with front and rear suspension shocks, springs, geometry and/or tires. It’s basically harmonics. The parts of the suspension start vibrating and reach a frequency where the vibration resonates through the whole system, and engineers say it has reached the systems “resonant frequency“, or the frequency at which a structure will literally shake itself to death. Left alone without changes to the environment and the structure will shake itself until it self destructs. Want to see a cool video of a highway suspension bridge doing just that? Google “Tacoma Narrows Bridge Collapse”. Spolier: in the thirties a suspension bridge was built across the Tacoma Narrows in Washington State. The engineers failed to take into account the effect of the fairly regular wind that blew through the bridge. The bridge reached resonant frequency and then self destructed.

Here’s the reason why the cause DW is hard to diagnose; it is created by many factors, mass, complication of structure, speed and strength of inputs, mechanical integrity of fastened joints, etc.

In cars when body panels start to vibrate, it’s a resonance issue. The solution change the design to a thicker panel, or slap a weighted patch on it to change the resonant frequency of the panel. FYI, it’s the same for a ship. For skyscrapers that shift it the wind several tons of mass will be installed on an upper floor. These are all solutions where the environment can’t be controlled and it’s easier to modify the structure.

On a jeep when DW strikes, slow down because the driver can control the environment by doing that. Theoretically speeding up could also stop it, it could also exacerbate it. So slowing down is probably the surest course of action.

On the front end of a jeep there is a very complicated structure of rods and bars and pipes and castings all tied together with mechanical fasteners with joints also meant to articulate. If that isn’t bad enough there are two very large pieces of spinning sprung mass that happen to be hung out at the worst possible location.

Every time a wheel goes into a pot hole, the front suspension vibrates. As long as the vibration does not happen at the system‘s resonant frequency, the vibration self dampens. But the resonant frequency for a system can change, as the physical attributes of the system change. Add bigger heavier tires, resonant frequency changes, steering damper wears, resonance changes, shocks wear, resonance changes, etc etc etc. Likewise once DW becomes prevalent, the exact nature of the cause is unknown because it could be one of many things, or the result of many small things. This makes diagnosis very hard because there is not a limited list of things like an engine (gas: air, fuel and spark) or (diesel: air fuel & compression).

 

[Rusty PW]

It's not that common - it's more amplified by the internet. It's like visiting a hospital then claiming all humans have cancer or are otherwise sick.

Hospitals are not for well people.

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