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Death Wobble, The Saga Continues


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I appreciate those of you who responded to my previous entry on this topic. I thought I had this beat but today while driving secondary county roads that are paved but rough, I had the DW kick in 12 times in five miles. It usually occurred when the passenger side tire would hit a bump and at speeds greater than 30 mph.

 

Tires, balance, alignment have been checked and a new trac-bar have been installed. The tie rod ends all have been examined. So where do I go from here?

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Did you switch the tars front to back? If no try it ...

 

CW

 

or i have seen many a times from the dealer that the tires can go bad or just be bad internally and they are throwing the balance off. it may come down to needing new tires.

 

Alex

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What kind of steering shock are you running? Is it new? Since it seems to be road induced in your case I would look more at steering and suspension components than tires or wheels.

 

Just a note, A steering stabilizer MASKS Death Wobble.

 

DOSEN'T CAUSE OR FIX IT.

 

If it goes away after replacement, you haven't fixed ANYTHING! You still have worn parts SOMEWHERE, your just masking them.

 

CW

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Just what Cwlongshot said -- steering damper does NOT fix death wobble.

 

We need more specifics. What speeds? "Over 30" doesn't help much -- how much over 30? 40? 50? 65?

 

What kind of bumps? Gentle bumps like good speed bumps, or sharp whacks like potholes?

 

Have you checked the wheel rims for runout? Have you checked the lugnuts to ensure that they are correctly torqued? What kind of shock absorbers are you running and how old are they? What are you running for front springs, stock or some after-market lift spring? If after-market, whose and what height and spring rate?

 

DW is not easy to track down. The problem is that it's a harmonic, and there are any number of factors that can set it off, but they may not be the ultimate "cause." I've had it in a box stock Grand Cherokee, and I've had it in one of the MJs. Never found out for 100% certain what the "cause" was in either vehicle, but in each case it only happened one time. With the Grand, it simply never happened again ... I didn't change a thing. On the MJ, I swapped on a different set of tires and never had DW again (so far).

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What kind of steering shock are you running? Is it new? Since it seems to be road induced in your case I would look more at steering and suspension components than tires or wheels.

 

Just a note, A steering stabilizer MASKS Death Wobble.

 

DOSEN'T CAUSE OR FIX IT.

 

If it goes away after replacement, you haven't fixed ANYTHING! You still have worn parts SOMEWHERE, your just masking them.

 

CW

 

Hey, thanks for yelling at me. I appreciate it.

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What kind of steering shock are you running? Is it new? Since it seems to be road induced in your case I would look more at steering and suspension components than tires or wheels.

 

Just a note, A steering stabilizer MASKS Death Wobble.

 

DOSEN'T CAUSE OR FIX IT.

 

If it goes away after replacement, you haven't fixed ANYTHING! You still have worn parts SOMEWHERE, your just masking them.

 

CW

 

Hey, thanks for yelling at me. I appreciate it.

 

Alex is right, I was not meaning to come off like I was yelling or upset.

 

Please accept my apologies.

 

This is a COMMON misconception. Doing me best to dispel it, that's all...

 

CW

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I was actually going to put a smiley at the end of my last post. I don't get offended easily on the internet. Hey, I used to belong to JU.

I am not trying to start an argument but, I have "cured" (OK, masked) DW in mostly stock XJ's with a good aftermarket steering shock.

I understand the whole concept of NVH and the various factors that are involved, and that there are varying degrees of DW. I had bad DW in my ZJ with 3" lift all due to Timberline tires. Changed tires and DW gone. And that most people that think they have DW have never really experienced it. Road surface induced shake in the steering on a XJ with a blown out shock is much worse that one with a good stabilizer. I don't consider this true DW, and that is kinda what I was trying to find out more info from Rundel for.

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Just a note, A steering stabilizer MASKS Death Wobble.

DOSEN'T CAUSE OR FIX IT.

 

I'm the dissent to this advice. Road (or not so road) debris took out the stabilizer on my first Mj. If you think about it, if the stabilizer has no bearing on DW then, theoretically, if the rest of the system where "harmonized" you could remove it without DW worry. The steering shock is the first place I look. If it's damaged or severely worn (and there is no other apparent wear) I replace it, re-balance the tires ($40 total repair cost) and continue on.

 

On the really bad advice column - even if the shock is a cover-up, it is effective and relatively cheap. The real question is - are you looking for a functional repair or proper repair?

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I understand the whole concept of NVH and the various factors that are involved, and that there are varying degrees of DW.

Sorry, but I very strongly disagree. Death wobble has exactly NOTHING to do with noise, vibration and harshness, and there are NO degrees of death wobble. Either you have death wobble, or you don't have death wobble. Period.

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I understand the whole concept of NVH and the various factors that are involved, and that there are varying degrees of DW.

Sorry, but I very strongly disagree. Death wobble has exactly NOTHING to do with noise, vibration and harshness, and there are NO degrees of death wobble. Either you have death wobble, or you don't have death wobble. Period.

What I was trying to get across in the rest of my statement is that alot of people who THINK they have DW really don't. This is what you are also saying I believe. Do you agree that you can have a tire or road induced shake in the front end, that isn't classic DW?

I worked for years on Jeeps at the dealership level and dealt with many front end complaints and never really understood DW until I felt it first hand. Once you experience it there is no forgeting it. BUT, if you have only read about it.....kind of like trying to explain how cold it is in Canada in winter to someone who has always lived in the Bahamas. They know what cold is, and have felt cold but don't really comprehend the degree of cold without being there.

And I AM NOT saying Rundel doesn't have DW, or doesn't have control arm issues. Or any other issues for that matter. Just simply tryng to establish if it is DW, or just a shake due to a bad stabilizer and some bad roads. I guess that we really need to hear back from Rundel for more symtoms and parameters before doing any online surgury.

 

"The problem is that it's a harmonic,"

 

I guess I'm lost on this one. I always figured that harmonics, or in this case dissonance, had everything to do with NVH.

:D

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Sure, you can have wheel shimmy that doesn't develop into DW. I've driven thousands of miles with slight shimmy. That's why I know it isn't DW -- 'cause I've also had the real deal. Makes me crazy when I see kids on NAXJA blathering about "verge of death wobble." WTF is "verge of" death wobble? Either it is ... or it isn't.

 

It's a harmonic because if the initiating shake or shimmy doesn't/can't induce a corresponding shake in the other wheel at the same frequncy, it doesn't escalate into DW. My first DW experience was in a box stock '99 WJ. Word is that the '99 WJs with export suspension had a horrible DW problem, but the standard US suspension didn't. Why? Different spring rate and shock valving. The export suspension happened to match the natural frequency of the spring with the bounce rate of a warped brake rotor at 57 MPH. Once you hit the harmonic, the oscillations become mutually reinforcing rather than mutally cancelling, and THAT's what DW is. My WJ had the optional suspension, which I believe either was the same as or was very close to the export suspension.

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Do you agree that you can have a tire or road induced shake in the front end, that isn't classic DW?

 

To answer for EAGLE, YES. Tire balance and Alignment are the BIG One's!!

 

The HARMONIC is a tough one to describe online..but I'll attempt it...

 

Lets set up a scenario, Your driving a mid 80's XJ with say 120,000 miles and not so good routine maintenance. The steering box is a bit loose but not major. You got some new snow tars last winter. After doing a lube and filter, the mechanic told you, you should think about replacing the TRE's soon. But the ol' girl is driving fine and you kinda forget about it. One day on the way to work there was a bad storm the night before and flooding everywhere. You don't worry as you drive a Jeep. You ford right thru the standing water with out a worry. Just before you get on the freeway, you go thru another puddle, but this one slows you right down. You make it thru but it seemed funny. Once on the high way you start to feel a little bounce in the front end. Then in a curve you hit a seam in the road and all of a sudden WHAMO the wheel is jerking all over the place, the front end of the Jeep is bouncing wildly. The jeep seems uncontrollable. You slam on the breaks and pull over clutching you chest. You KNOW you just totally destroyed the front end of your jeep. You get out and give everything a look see, but find nothing....you have just experienced DEATH WOBBLES. What caused them?? Well a combination of parts and circumstances.

 

1)Your steering box is loose (Steering wheel is not positive when turning)

2) Your TRE's are loose.

3) You picked up some mud from that puddle before entering the freeway

4) You hit a bump in a turn

 

Well, that bump "set" the harmonics in motion.

 

Think of a bicycle wheel. Have you ever held one when someone spun it. Do you remember that force when you tried to "wiggle" the wheel. You know that's centrifugal force. The force imparted on a wheel set into motion. the force keeps the wheel straight. Even though the TRE's and steering linkage has play, you don't feel anything. Well add the out of balance from the mud and the bump in the road and the slight turn of the wheels and the wheels where forced to the right as far as the "slack" in the TRE's would allow. almost instantly the centrifugal forces forced the wheels back in the other direction only to pass center and slam in to other end of the slop in the front end. this continues back and forth, back and forth SUPER fast and IS the harmonics that is DW. Think of a figure * sideways, the infinity sign. It continues and continues until acted upon by something to stop it. In this case you hit the brakes that do NOTHING to the actual DW other than eliminate the motion that in turn stops the DW.

 

Eliminate the mud, the bump and the slight turn and that jeep could likely drive fine again for some time. More likely, the severity of the DW further wasted the steering linkage and TRE's to the point where now they are too bad and MUST be replaced.

 

 

I hope that better explains DW.

 

CW

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I hope that better explains DW.

 

CW

One of the genuine mysteries about DW is how you can never adequately explain it to someone who has never experienced it ... and there's no need to explain it to someone who HAS experienced it.

 

Well...I TRIED... :cry:

 

I didn't post it to preach to the choir... :cry: :cry:

 

CW

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see, i think you can have BOTH.

 

you can have wobbles that don't escalate to DW then at the same time you can get DW randomly.

 

this is what my heep does. I only get DW when I'm doing something stupid though (aka going 65-70mph, or accelerating rapidly past 55 over bumps)

but i get wobbles ALL the time that i can stop from escalating by slowing down or just coasting the right way.

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my DW has been fixed(for now) by replacing the LCA's on the MJ. i still get a slight shimmy once in awhile but i need to replace the uppers too.

 

i also had a shimmy that looked like a mild form of DW on the TJ and fixed that by modifyin the track bar bushing. i say it looked like mild DW is because i knew a spot in the raod that caused it and i looked out window at the tire one day and seen the tires.

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There is no such thing as a "mild form of DW."

 

If the vehicle can be controlled and driven, and if you didn't pee in your pants and watch your entire life pass in front of your eyes, it was NOT death wobble. There is a reason it's called "death" wobble.

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There is no such thing as a "mild form of DW."

 

If the vehicle can be controlled and driven, and if you didn't pee in your pants and watch your entire life pass in front of your eyes, it was NOT death wobble. There is a reason it's called "death" wobble.

 

ok so it was suspended animation wobble...

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There is no such thing as a "mild form of DW."

 

If the vehicle can be controlled and driven, and if you didn't pee in your pants and watch your entire life pass in front of your eyes, it was NOT death wobble. There is a reason it's called "death" wobble.

 

ok so it was suspended animation wobble...

Or "shimmy" ...

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so what fixes a shimmy?

 

cause i've got a "suspended animation wobble" and a "pee your pants and watch your life flash in front of your eyes wobble"

 

does that mean i need to fix TWO problems (where's the shoots self in head icon?? :D )

 

but my DW doesnt make the truck change lanes or anything crazy it just shakes you like a damn paint mixer and everyone around slams on brakes and i pull off and coast to like 30 then it stops and i go again

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