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-   -   Intelligent Question About Death Wobble (http://www.jeepforum.com/forum/f9/intelligent-question-about-death-wobble-1541167/)

OzzLee 06-25-2013 11:24 AM

Intelligent Question About Death Wobble
 
I know what you're thinking, not ANOTHER thread about DW. Don't worry, this isn't the usual "OMG what's going on" post.

I've spent the past week reading up on the infamous DW. I've read the forums and the article in the recent JP magazine, and what I gather is its like an old strand of christmas lights...one light fails and it mucks up the entire system. That and steering stabilizers only mask the problem.

My question: has anyone noticed if the wobble is brought on in different ways by different parts going bad. For example, if wobble from hard breaking or acceleration points to a different faulty part than wobble brought on by a bump in the road?

I ask because I can't make my Jeep shake if I try. I drive fast, slow, swerve, run over bumps, and anything else that would get me pulled over for reckless driving and the Jeep drives smooth and straight as an arrow. Then a few days later, driving casually on a relatively smooth road that I traverse on a daily basis, it shakes. I turn around and try to recreate the event.....no wobble.

When I have a free weekend, my step-dad and I will check all the joints and bolts and what not. I'm confident we can find the chink in the system.

SlackJaw 06-25-2013 11:36 AM

Quote:

Originally Posted by OzzLee (Post 15605190)
I know what you're thinking, not ANOTHER thread about DW. Don't worry, this isn't the usual "OMG what's going on" post.

I've spent the past week reading up on the infamous DW. I've read the forums and the article in the recent JP magazine, and what I gather is its like an old strand of christmas lights...one light fails and it mucks up the entire system. That and steering stabilizers only mask the problem.

My question: has anyone noticed if the wobble is brought on in different ways by different parts going bad. For example, if wobble from hard breaking or acceleration points to a different faulty part than wobble brought on by a bump in the road?

I ask because I can't make my Jeep shake if I try. I drive fast, slow, swerve, run over bumps, and anything else that would get me pulled over for reckless driving and the Jeep drives smooth and straight as an arrow. Then a few days later, driving casually on a relatively smooth road that I traverse on a daily basis, it shakes. I turn around and try to recreate the event.....no wobble.

When I have a free weekend, my step-dad and I will check all the joints and bolts and what not. I'm confident we can find the chink in the system.

First, do you have teh shimmy or the Death Wobble?

I remember hearing tale that you could tell under certain conditions if it might be your control arms....under braking v accel, and/or possibly in 4wd or not. I tried all these and couldn't perceive much of a difference....and it ended up being my CAs anyway. If you've got no wobble, but when you brake you do, then I would say it's likely you have runout on a rotor or "warped" in layman's terms...but if that's throwing you into full blown death wobble, you probably have other issues.

The methodology should be this:

Make sure your tires are balanced well and do not have uneven wear. Make sure your toe is correct. Check wheel bearings and ball joints. These are all easy checks and should be done regularly when you rotate tires anyway.

Do a dry steer test. This is also an easy test, but is typically only run if something doesn't right. Look particularly at the trac bar, but certainly all the other joints.

If all this checks out, then it's your control arms. This is usually the last check, as it is more difficult to confirm, but really, if everything else is good, this will be it. If you have 10+ years on the stock ones, it's a fair bet they are toast anyway, and I'd put even more odds on these if you are lifted.

I also had some intermittance when mine first started shimmying...kind of like you are referencing, like it would wobble all the time, but then if I wheeled it (flexing it out), the trip home would be smooth as glass. Again, final determination in my case was that it was my CAs. Another test I happened to do, (after my D/W became full blown) was to take the lift off the front. D/W was gone. Put the lift back on, D/W was present.

TheBoogieman 06-25-2013 11:39 AM

It's all the same and if you get DW,you'll know it and be changing your underwear quickly.I've had unblanced tires or uneven tire wear cause an occassional wobble,but not DW.

TheBoogieman 06-25-2013 11:49 AM

Quote:

Originally Posted by SlackJaw (Post 15605247)
I remember hearing a tale

Me too.Was it a tale of a fateful trip
That started from this tropic port
Aboard this tiny ship?:wave:

J03_TJ 06-25-2013 12:08 PM

363 Attachment(s)
I've used the passenger test to determine I I had DW. Make sure they are only used to driving/riding in cars with good suspension characteristics. Have them ride along on a road that will trigger your wiggle. If they grab the bar above the glove box and look at you really scared, you probably have DW.

TheBoogieman 06-25-2013 12:12 PM

Quote:

Originally Posted by J03_TJ (Post 15605393)
I've used the passenger test to determine I I had DW. Make sure they are only used to driving/riding in cars with good suspension characteristics. Have them ride along on a road that will trigger your wiggle. If they grab the bar above the glove box and look at you really scared, you probably have DW.

But if it's a girl with bladder problems,you have to clean the pee off your seats.(Don't ask how I know that one.):(

J03_TJ 06-25-2013 12:51 PM

363 Attachment(s)
Quote:

Originally Posted by TheBoogieman

But if it's a girl with bladder problems,you have to clean the pee off your seats.(Don't ask how I know that one.):(

Funny. Me and a buddy went hunting one day in mine a few years back when I was having DW problems. I'd have to say he is my most "redneck" friend, doesn't mind fighting, chews and doesn't spit, all round tough guy that I wouldn't think would be scared of anything. He was scared the whole ride home after it happened. Not me though having been through it a few times.

matteo92065 06-25-2013 01:29 PM

Ozzlee, I feel your frustration/pain.
My DW is also very intermittent. I really think that mine is most evident when it is cooler out and the jeep (and tires) are cool. [run on sentence] I go up a hill in the morning and the thing will shake the hell out of everything, have to pull over and get it under 10mph, catch my breath, turn around to go home and put it in the garage and take the VW to work [/run on sentence]. BUT, on the way home the thing is smooth as can be. So I turn around AGAIN, head up the hill and all is good and almost perfectly smooth! What gives?

biffgnar 06-25-2013 01:31 PM

22 Attachment(s)
Wasn't Blaine once upon a time trying to collect info to use onset speed as an indicator of where the problem was? Maybe I am misremembering.

SlackJaw 06-25-2013 01:38 PM

Quote:

Originally Posted by biffgnar (Post 15605750)
Wasn't Blaine once upon a time trying to collect info to use onset speed as an indicator of where the problem was? Maybe I am misremembering.

sort of...between 47 and 53 iirc his last statement on it, but that's where it starts for everyone...I mean the oscillation of the axle is what it is, regardless of what starts it.

JEK3 06-25-2013 01:38 PM

Quote:

Originally Posted by matteo92065 (Post 15605746)
... I really think that mine is most evident when it is cooler out and the jeep (and tires) are cool...

I noticed a temperature dependence with mine also. I believe it is because the CA bushings are stiffer when they're colder.

SlackJaw 06-25-2013 01:38 PM

Quote:

Originally Posted by TheBoogieman (Post 15605411)
But if it's a girl with bladder problems,you have to clean the pee off your seats.(Don't ask how I know that one.):(

pics please.

SlackJaw 06-25-2013 01:39 PM

Quote:

Originally Posted by JEK3 (Post 15605778)
I noticed a temperature dependence with mine also. I believe it is because the CA bushings are stiffer when they're colder.

this. Except mine was the other way around...warmer it got, more it shimmy. This seems to make more sense to me considering the properties of rubber.

matteo92065 06-25-2013 01:49 PM

I'm running all JJ's on control arms.
Yes on the speed. "Magic speed" is right around 50mph. I can keep it just under the magic speed and it is like tires are out-of-balance. But if I immediately try to 'power' through the shake it will get worse and develop into DW. If I wait a few minutes at just below the magic speed then 'ease-into-it' I can get up to 60-70 mph with no drama.

SlackJaw 06-25-2013 02:55 PM

Quote:

Originally Posted by matteo92065 (Post 15605828)
I'm running all JJ's on control arms.
Yes on the speed. "Magic speed" is right around 50mph. I can keep it just under the magic speed and it is like tires are out-of-balance. But if I immediately try to 'power' through the shake it will get worse and develop into DW. If I wait a few minutes at just below the magic speed then 'ease-into-it' I can get up to 60-70 mph with no drama.

Push it past 70 and you should be able to find another magic speed for a even wilder ride :D


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