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Death wobble saga


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My son and I finally solved the death wobble ("lateral shimmy", as it is called in the suspension business - I learn something new every day :roll: ) problem with the 89 MJ. I know that many folks here have had the problem and I thought I would cover the steps that we took to solve it (over a 5 month period). It is a daily driver, and he was experiencing it off and on depending on the speed (varied but mostly between 35-55 MPH initally) and the presence of bumps in the roadway.

 

First, I noted a slight looseness (like 3/32 play) in the pitman arm shaft (where it entered the steering box) after the engine rebuild but believing it was normal took the truck for a tire balancing and front end alignment - because a search on the articles in the forum showed many folks were recommending that step. After balance and align the DW came back with a savage vengance on the way home from the shop.

 

We chose to replace the steering box and pitman arm with a rebuilt unit from NAPA. DW seemed to be gone so we watched and waited....DW came back again (39-45 MPH) and examination of the front end seemed to indicate a bad upper ball joint on the driver's side. We replaced (both sides) upper and lower ball joints with MOOG brand, (driver's side stud fell out of the ball when removed) and checked it again on the road. DW still there (40-43 MPH) but much less severe.

 

Examination of the suspension again showed minor play in the track bar mount, so new bolts with lock washers were installed. Shaking the vehicle from side to side (pushing and pulling on the fender) while someone watched from below showed the ball stud in the track bar seemed loose. Ordered a MOOG brand replacement track bar from Rockauto.com.

 

Replaced trackbar and when examining the old one found the stud to have worn inside the ball to the point is was almost falling out. Test drive showed no DW tendencies at any speed or road condition. jamminz.gif

 

Now, I know that many folks on here believe DW is caused by out-of-balance tires. In fact, you could make a strong argument that the DW caused the damage to the ball joints and the track bar...I will not refute that. But I do believe that DW can and is caused by a combination of factors rather then just one aspect especially when considering the design of the axle and it's mounting.

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I'm still going with track bar as the cause. when i lifted mine i knew my ball joints were shot on the drivers side but i didnt replace them. i didnt run a trac bar for awhile because i mainly stayed offroad and less then ten mph. i eventually put it on and drove it as my DD. no DW. i ended up breaking that bar and had to drive a ways back home and boom, DW. got a new bar, put it on, started to be my DD again. no DW. all this with bad ball joints and I'm sure my steering box is f**ked too. well that bar stripped out and then, you guessed it, had DW again. even with all those other problems i KNOW i have, they didnt seem to contribute to DW. i mean i didnt even get a shimmy :dunno:

 

oh and did i mention i never got it aligned at ANY point during all this. i did have the tires balanced but thats it. i guess everything just canceled each other out or something but I'm telling you if you would of got that track bar first, it would of been gone. thats just my crazy theory but then again ive got the p.o.s outside to prove it

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Our 96' ZJ had death wobble,

ball joints were OK, trac bar & TRE's seemed marginal.

 

Ended up replacing all the steering TRE's (one at a time, worst to best), and the trac bar,

DW minimized, but would still rear it's ugly head from time to time.

 

Everything checked out,

only had a slight lift (2") on factory TJ 30's, and I was :hmm: .

 

Then I thought of the factory windowed ZJ control arm bushings

(they looked fine).

 

Replaced the LCA's with aftermarket arms that I had laying around (solid bushings),

and the DW never came back.

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One thing Ive noticed with this issue, is with the alignment. I had this issue for a little while, replaced all the steering parts, to no avail. Did an alignment on it and made sure I did the caster angle too, and I havent seen it since. If you have too little caster, DW will be more likely to happen because it would be easier for it at less of an angle, and if it goes into negative number then you get the grocery cart woobity wheel syndrome..... same principle as DW. And most alignment shops won't mess with the caster on our trucks, especially if it needs special shims, like my 87 did. Adjustable contol arms would give this adjustment, but if youre mostly stock like I am, theres really no need for them.

 

And I agree that wheel balance doesnt cause DW, but an unbalanced wheel at just the right speed will cause DW to start under the right conditions. The wheel balance didnt cause it, the worn or loose parts casue it but wheel unbalance puts it into motion.

 

Sometimes fixing one part will get it to go away, because maybe that part was the worst worn, or maybe balancing your tires will cause it to go away because they no longer set the DW off. It has to be the right combination to set it off or get it to go away. Thats all there is to it.

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Good info, as I'm now tracking down a DW scenario of my own. Funny thing is, I never had DW until I started actually fixing stuff in the front suspension. Once I got around to replacing the UCA and LCA bushings, I nailed a bump on the highway and experienced a horrendous shaking, something akin to a tankslapper on a motorcycle (though I didn't have to change my pants...). Got Moog balljoints, steering stabilizer, trackbar, and some other crap ready to go in. I think I'll take a look at the trackbar first, based on this thread. Sometimes when I'm driving, I think I can feel something "loose" feeling, almost like some piece has slop in it and is knocking around (I can't decide if I'm really feeling that, or if it's just regular bumps in the road that I'm paranoid about now that I've gotten DW a few times). I don't drive on the highway until I get this sorted out, but it sucks that I'll always be wondering "did I really solve it?" or if it's just lying in wait...

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:agree:

I found that one place it always happened, that was a good spot on city street and returned there after the TB bracket repair. Was like you,cringing if it was gonna return! At least it was a good spot to pull off the road. Got my confidence back after no DW!!!

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After reading some of the responses it occurred to me that I neglected to add: we replaced the UCA and LCA and bushings when the engine was pulled for the restoration. Although he wanted to lift it we agreed to leave it stock for the time being until we were sure all the bugs had been worked out. The really unique thing about his truck was that with each part we replaced the DW came back at a different MPH speed. Makes you wonder if there is a specific speed for DW depending on the part that is needing replacement.. :hmm:

 

Its true that if you find one 'spot' on a road that causes the DW you alwys cringe when you hit it...just in case it does reappear, but at the same time you can go there to see if you've fixed the problem as well.

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my question is what kind of alignment shop suposedly aligned your truck with bad ball joints and track bar?

 

Firestone.

 

But - the purpose of this thread is to show the problems we experienced could have been one or all the itmes we discovered.

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  • 1 month later...

I'm having some death wobble problems. It's only after I hit a bump and if I let go of the steering wheel and let it go to the right it stops. I took it sunday for a balance, rotate and alignment. The wobble didn't happen on the way home or to work this morning but on the way home form work, I hit a bump and there it was. Not nearly as bad as it had been but it was there. Also, after the alignment, my steering wheel is off 45 degrees. I'll take that back and have it fixed. What else should I tell them to look at while it's up there?

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Its really tough to say there is any one cause. There are folks who will swear that it is solely balancing, but our experience was different. We have yet to replace the TRE or the steering arm, but did not have any more problems with DW until my son hit a curb piece the other day...and after that he had DW at 45 MPH when hitting an expansion joint in the road. I swapped the tires front to rear and the DW went away...meaning it was a balance problem this time.

 

Folks at the local tire store said his tires have dry rot which they say can also cause DW. I say it can't unless the belts shift (which would be at best a balance problem or at worst a blowout or tread separation).

 

We are gonna replace the last suspension parts (TRE and steering arm) and then see about tires. I'll let ya'll know what effect that has.

 

As a side note...I looked under the WJ the other day and noted the upper 2/3 of the UCA are mounted inside the frame rail so they cannot move laterally....therefor pinning the axle in place without allowing side-to-side motion (otherwise the axle is quite similar in configuration). I wonder if we welded 1/4 inch plate down the frame rails and along each side of the UCA on the MJ if it would stop this foolishness once and for all (this would not work if the truck was lifted, but he has decided he doesnt want a lift).

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I just had the wheels balanced, rotated and aligned. Would the steering wheel being out of whack cause it? I'm thinking not because before the alignment the wobble was worse and the steering wheel was positioned correctly. Is it possible they didn't tighten something enough or get the camber right.

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On my xj waggy, it had an adjustable track bar, on the frame bracket end. I thought the po had made it up, and it appeared to have some looseness in it, so found the stud to be loose in the bracket. Couldn't tighten it on the jeep. Figured time for new bracket.

Went to jy, found nice tight track bar, got bracket and all.

BTW, this is the easiest/best way to replace the track bar, due to the access on the bracket end.

After about a year, got looseness again. :wall: Found bracket end loose again. Took bracket/bar out, and found stud loose in bracket.

This time decided to investigate. Found that when installed previously by the po, the stud hadn't been full seated in the bracket, stud still tight in bar. Had to chisel the nut to get it off, cleaned things up, found new castellated nut, and installed the bar end/bracket assy while off the Jeep.

Now I know the thing is tight, and am thinking access causes these things to not be fully seated when installed while the bracket is on the jeep.

Taking the bracket off is way easier than fighting to get to the cotter key and nut on the rig. :banana:

Oh, and had some junk/good looking Goodyear wrangler 30x9.50s that werent helping, though I still run them. :doh:

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DW is a cause of numerouse sloppy parts in my opnion. on my 86 xj it was the track bar, on my 96 i went straight to the track bar and it fixed- nothing, then i did my ball joints and both my lowers fell apart while removing them. so add together out of balanced tires, loose suspension joints, bad ball joints and you get death wobble, or any combo of out of spec old parts IMO

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I'm having some death wobble problems. It's only after I hit a bump and if I let go of the steering wheel and let it go to the right it stops. I took it sunday for a balance, rotate and alignment. The wobble didn't happen on the way home or to work this morning but on the way home form work, I hit a bump and there it was. Not nearly as bad as it had been but it was there.

If you can let go of the steering wheel and it stops, and if it's not nearly as bad as it was -- you do NOT have death wobble, you have wheel shimmy.

 

If you can continue to drive and if it isn't a struggle to even keep the vehicle on the road -- it ain't death wobble. There's a reason it's called DEATH wobble.

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depends on how much faith you have in yourself but i think if you can do reg maintance on your rig you can swap out a track bar, or do ball joints. have someone get in your truck and jerk the steering wheel around while you look and inspect for clunking/loose parts (track bar,tie rod ends etc) i did my ball joints in the driveway and they were a bit of a pain but not to bad, and i used a ball joint press i rented from schucks. you can check your ball joints by jacking the front up then by hand lifting/twisting the tire with no load on it. if it clunks or you can feel verticle movement the ball joints shoud be replaced.

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