Had my first death wobble this morning

[summerinmaine]

I was on the slab on my normal route this morning, doing about 60mph (and slowing a bit for some traffic ahead) and I hit a small bump. Death wobble started, but was pretty benign, and ceased after I got it down to about 35mph or so.

 

I know a number of things can contribute, but since this was a classic induction sequence, should I start going through the checklist, or just assume that this was a matter of being in the wrong place at the wrong speed?

[CWLONGSHOT]

With out knowing anything sans what you just described. i would say its likely you have a couple things going on at once...nothing really bad...but the combo of worn parts all took part in today's "fun" !!

 

BTW, you got off easy!! Full blown DW doesn't stop until you pull over and completely stop, get out and circle the jeep TWICE looking behind you for the parts you KNOW fell off!!

:eek: :eek:

CW

[JeepcoMJ]

the 3800 does this.

 

it's a contribution of bad trackbar, and I think bad driver's side UCA bushings.

[jared]

check everything, its only gonna get worse. if it happens once its gonna happen again.

 

check the tie rods, track bar, all bushings, even get the alignment checked. the tires can even cause it.

 

its not just a track bar issue like most people say. its fukin evil :hateputers:

[JeepcoMJ]

hehe, I feel the same way.

 

I'm just puttin off fixin it b/c i don't need to drive far, or over 55mph very often right now, and the whole front axle itself could be causing it...it's bent at the outer left "C" knuckle so it needs replacing...just lookin for one that's got 3.73 gears and is a disco and high pinion.

[Eagle]

If you can even think of describing it as "benign," I respectfully wonder if you had genuine death wobble. The real deal as CW said, usually doesn't abate until you come to a complete stop. By that time, your life has flashed in front of your eyes and you've wet your pants (at the least).

 

I've had it twice, once in a brand new WJ Grand Cherokee and once in the '88 MJ. There is no way I'd describe either incident as "benign."

[summerinmaine]

With out knowing anything sans what you just described. i would say its likely you have a couple things going on at once...nothing really bad...but the combo of worn parts all took part in today's "fun" !!

 

BTW, you got off easy!! Full blown DW doesn't stop until you pull over and completely stop, get out and circle the jeep TWICE looking behind you for the parts you KNOW fell off!!

:eek: :eek:

CW

 

I know what full blown DW feels like, and that's why I'm not too concerned about this isolated incident. But I certainly don't want it to become a habit.

 

Additional info: I bought the MJ about 1500 miles ago with a lot of miles on it, but a recent (unknown source) 3" lift. It has Skyjackers, an adjustable track bar, new ball joints and uprated LCAs. I'm beginning to suspect that there are some alignment/adjustment issues, however, and I'm inclined to have the front tires spin balanced, just on general principles.

[summerinmaine]

If you can even think of describing it as "benign," I respectfully wonder if you had genuine death wobble. The real deal as CW said, usually doesn't abate until you come to a complete stop. By that time, your life has flashed in front of your eyes and you've wet your pants (at the least).

 

That's my thinking exactly. The wobble started, I recognized it immediately as no big deal, began to slow, and then it stopped. That's why I'm pretty relaxed about the whole experience, and other than checking some of the routine stuff, I'm not inclined to start throwing dollars at the problem.

[JeepcoMJ]

I feel exactly like that regarding my experience.

[Eagle]

The PO probably lifted it without adding shims to bring the caster angle back up to where it should be. I would agree on starting with tire balance, though.

[Mountianrider]

I had an 88 MJ with a horrible case of death wobble. The first time it happened I thought I was lossing a wheel. I put new quality shocks on the front and did a front end alignment; That is, I used a couple of tape measures and set the front Toe; In about a one sixteenth of an inch.

I drove it for quite a while, about a year, before selling it to a coworker: I had to get him away from a Dorf Ranger. Now he is a Comanche nut!

Any way the wobble has not happened since. However, there were a couple things about this death wobble. The wheels always looked like they were not vertical, but splayed outwards, like the previous owner had been doing some jumps. The wheels also appeared to be splayed outwards when looking from the nose. After my garage aligment this appearence improved, but still did not look right. It was 2wheel drive MJ.

You can tell that the death wobble is still lurking and that something else needs to be corrected. Obviously the caster is off. The wheels just are not vertical. I'd say incorrect caster angle is the main cause for death wobble. Good shocks and some toe in can help stop, but not cure, the dreaded death wobble. Now I agree with Eagle about needing to add shims to correct the castor angle, but where are the shims located? I am sure that the wobble is 80% caused by incorrect castor angle.

:popcorn:

[JeepcoMJ]

yea...shims...where are them?

 

and I have not 1 but 2 jeeps that have their rims/tires "splayed out" on the front end.

 

the 3800 it's more on one side than the other...so an axle replacement will be happening.

 

on the 89, well, it is fairly noticeable....

[ORCA]

The only time I experienced 'genuine' DW was when the bolt holding my trackbar on the axle sheered off and there was about 1/2" of it left holding the tracbar on.

 

This all happened on the freeway mind you. And if you didn't already know the speed limit on CA freeways is posted as 70mph but you NEED to go 80+ to keep up.

 

Scarriest thing that has ever happened to me while I was in a Jeep (and i rolled that one twice!)

 

My answer would be FIX IT NOW. Follow everyone's advice. It is not something to be takin lightly - if it is in fact DW.

[JeepcoMJ]

The only time I experienced 'genuine' DW was when the bolt holding my trackbar on the axle sheered off and there was about 1/2" of it left holding the tracbar on.

 

This all happened on the freeway mind you. And if you didn't already know the speed limit on CA freeways is posted as 70mph but you NEED to go 80+ to keep up.

 

Scarriest thing that has ever happened to me while I was in a Jeep (and i rolled that one twice!)

 

My answer would be FIX IT NOW. Follow everyone's advice. It is not something to be takin lightly - if it is in fact DW.

 

check the "TRE" on your trackbar. mine is loose and that's definitely the problem

[Duner]

I think the club experience shows with questions like this. First check all of the front suspension components especially the track bar mounts then have a knowledgable shop perform the front end alignment. (I'm not talking about Midas or Sears you need a shop that understands how a lifted vehicle differs from stock, stock settings will not correct the problem on a lifted truck). I have actually learned more from working with the mechanics at the shop my dad uses, and they don't over charge - $39 for a two wheel and $49 for a 4 wheel alignment and they road test the setup and check it again and they won't sell you a lifetime alignment to many pot holes in this city, but they will align your truck even if the parts are worn and then tell you that should replace or repair certain parts in the near future ( I hate those shops that find a worn ball joint and then want you to spend $1000 to rebuild the front end so the guy can set the toe-in).

[CWLONGSHOT]

Here is the "shim" that Eagle has referred to:

 

 

(Photo, borrowed from http://gojeep.willyshotrod.com/HowtoAlignment.htm )

 

 

It goes behind the lower control arm MOUNT to effectively, lengthen the OA length of the lower control arm, . Thusly, increasing the caster.

 

CW

[Mountianrider]

Thanks CWLongshot, added it to my favorites; :cheers:

[summerinmaine]

Yeah, thanks for that. But what if you need to SHORTEN the effective LCA length? :brows:

[jared]

Yeah, thanks for that. But what if you need to SHORTEN the effective LCA length? :brows:

 

custom arms

[Eagle]

Gents, adding shims (as nicely shown in CW's pics, thanks for that) increases caster, which can help alleviate death wobble. But if the wheels appear to be tilting in (or out) when viewed from the front, that's a camber issue, not caster. Shims won't affect that. It's considered non-adjustable in the XJ/MJ. The only fix, if the camber angle is really out of spec, is to replace the ball joints with offset ball joints.

[Mountianrider]

:eek: OPPS! Ok, About them Castors:

 

How do you suppose these Comanches end up with these front wheels splayed apart? Are these idiots jumping them?

:popcorn:

 

I did put a straight edge on the bottom of the axle of the Comanche with front wheels splayed apart and I could not detect that the axle tube had been bent or deformed. That was a 2 wheel drive.

 

Thanks for pointing out that addressing castor with shims will still not effect the front wheels being splayed outwards, which is a camber issue.

:bowdown:

[Eagle]

I think it's usually an optical illusion. The flares aren't vertical, so there's no accurare reference line. The only way to know for certain is to take it to a good alignment shop and have them take rthe readings. Next best would be to park on a known-flat & level surface and put an angle finder on each wheel. They should both read zero.