Diagnosing Death Wobble

[outracing]

Okay everyone, so I have searched, and found a lot of info, I would like to have it all in one thread, plus I have a few symptoms that I would like to toss out there that I didn't see in other threads.

I have a 1999 xj, with 99,000 miles on it. It has a four inch "Bastard Lift" and is strictly an on road machine. I use it to plow snow in the winter. After the lift went on, I had death wobble. I was corrected by having an alignment done at my local Conrads. The only thing that I have done since the alignment is go form the factory 215/75/15's to a set of 225/75/16's from a Jeep Liberty. The tires are brand new and balanced properly. It ran and drove fine for about 1000 miles after the new tires and wheels, but suddenly the death wobble is back and worse then ever. It happens at any speed above 30 miles an hour and 95% of the time it is while I am making a small curve either on the highway or on any of my local streets. I have spent a lot of time under the front end and can't find anything that is loose or worn.

My question; has any one encountered this exact problem, and if so, how was it corrected. Also, any other death wobble issues, what did you change or fix to correct the problem. I should still be okay on the alignment even though I when to a slightly taller tire and wheel right?

 

[Elmateo487]

Look under the car while someone put the car in reverse and taps the brakes on and off, letting the car move a few inches at a time. Watch your pinion angle to see if it moves. Also have someone rocks the steering wheel back and forth hard while you are watching the front steering.

These things, I think, are necessary to see if something is lose. Sometimes you can't move it with your hands and brunt force, and the whole weight of the car needs to do it.

 

[Elmateo487]

In addition. My death wobbles were from blown control arm bushings, and track bar joints.

 

[Alaskan89XJ]

http://www.kevinsoffroad.com/techarticles/deathwobble.html:windows:

 

[VAhasnoWAVES]

have someone turn the steering wheel while the car is under its own weight. look for slop in the steering and track bar. even a little can cause a big problem.

put the jeep on stands and grab the wheels to see if you have play. check the BJs (6 and 12) and unit bearings (3 and 9).

what is your castor at? going to bigger tires will result in a change in tow. you should check it, easy enough to do in your driveway. i would try to identify the cause of the wobble before getting it aligned again.

beyond that... the only thing left is your CA bushings.

good luck.

 

[Teephphah]

http://www.kevinsoffroad.com/how-to-fix-your-own-death-wobble/

Link in the post above didn't work for me, but got me close enough to find this one. I'm learning a lot, so THANKS!

 

[DougJ]

OP, I know you said the tires are balanced properly, but you might want to verify that. You said it frove fine for 1000 miles and then came back. You may have thrown a wheel weight. You possibly have something loose as well, and just havent found it yet.

I just changed the lift height on my XJ, changed control arms as well. I'm actually going to less lift with my new setup. On the first test drive I had DW pretty bad between 40 and 50mph. The "oh crap I'm gonna lose control" kind of DW.
I found the trackbar worn at the frame end. I got the parts in the other day and rebuilt the joint, and while the DW was reduced to less scary levels, it was still pretty significant. I fiddled with the caster, looked for any thing else loose etc. Still there. It's about a 30 mile drive to town for me with 1/2 of it on a two lane mountain road. Once I was sure there was nothing loose, and I knew it was speed specific, I figured I had to get a balance before any more troubleshooting. I went ahead and drove on in today, avoiding the troublesome speed range as much as possible.
30 minutes at Americas Tire for a balance while I ate lunch and it drives as good as new. I'm getting ready to put a different front axle in and I'll inspect everything again at that time, but I think I'm GTG.

Doug

 

[offroadordnance]

I had a similar problem after installing my lift. I shimmed out the LCA's and no more wobble until a few weeks later. I changed out the stabilizer, tierod, and trackbar with no luck. Then i had the tires balanced and the wobble went away. The tires had only 5,000 miles on them and were put on a few months before the lift.

 

[Buckskinner38]

I had a similar problem after installing my lift. I shimmed out the LCA's and no more wobble until a few weeks later. I changed out the stabilizer, tierod, and trackbar with no luck. Then i had the tires balanced and the wobble went away. The tires had only 5,000 miles on them and were put on a few months before the lift.

Could you tell me a little more about shimming out your lower control arms... I'm having the same problem. I installed a 3" lift kit, new inner and outer tie rods, steering ball joints, alignment, wheels balanced, new bushings for the traction bar, yadda, yadda, yadda. Im now considering on getting new adjustable control arms, and replacing the ball joints. The truck run fine with a little bit of death wobble when ever I hit a bump in the road. I can take it on the highway but if I hit a small dip or pot hole the DW kicks in. GoJEEP.com talked about adding shims to correct this in the lower control arm... but where do you get the shims and how is it installed?

 

[offroadordnance]

Napa sells them for a dollar or two. The counter guy couldnt find them but I think he looked them up under body shims. It's a .125" thick or so shim and goes behind the rear most bolt head of the lower LCA to increase positive camber. Theres a chart on the net somewhere with recommended shim thickness for different lift heights.

 

[offroadordnance]

Sorry caster not camber

 

[Buckskinner38]

Very Cool... Thanks for the info. I did do some searching on the net for shims and I get all sorts of returns for every kind of shim except that particular one ( except on www.factorychryslerparts.com. I just don't want spend 5.00 per shim plus shipping and handling with out knowing how many I will need ) The thickness info was a big help. Got to admit, I heard it first on this forum. That info should help me when dealing with the guys at the parts counter.

 

[offroadordnance]

Cherokee forum has a drawing with dimensions in a thread titled " lower control arm caster shim template " They don't need to be perfect to work if you fab them yourself.

 

[DougJ]

I hacked up some shims out of some .090" aluminum sheet. I made 6 of them in about 15 minutes. Sorry I don't remember where I got the dimensions/template, but it was probably the go-jeep site, I can't get there from work for some reason to verify.

They don't have to be perfect.

 

[VAhasnoWAVES]

dont just throw shims at your LCAs... measure your caster first.

 

[DougJ]

dont just throw shims at your LCAs... measure your caster first.

Obvious but good point.

There's a nice guide on the go jeep site for caster vs lift that should get you where you need to be.

 

[Buckskinner38]

picked up some flat strap today and I'm gonna make some up before the week end. Question as far as measuring goes. Go Jeep recommended using a bevel square...

with a level on it against the diff cover bolt heads that are above and below the axle or use the flat round area next to this. Then use a protractor the read the degrees. Better still, and what I now use, is a angle finder. I have checked many XJ's including one that was still on the showroom floor and providing you are on level ground then it should read 87.5 degrees for stock if done as shown. This is not the true caster angle as the steering knuckles are at a different angle but they will always be relative to this angle so it is used as a reference point.

This quote seems a little vague to me... Could someone elaborate as to what exactly he's talking about? I get the idea on measuring from center rear hub to front hub but how do you know if your getting the right tilt that a person would be looking for?

 

[offroadordnance]

The author of the article has measured the diff angle on XJ's with factory correct caster on a level surface. The angle as measured from the diff is different than what the alignment shops measure at the knuckles. His angle is what most shadetrees can measure with tools on hand. With an actual 3" lift (not advertised) about 3/16" shim should be required. The rear LCA bolts on your rig should appear loosened, some shiny threads showing, and there should be some clean new shims in there if the alignment shop added caster.

 

[Buckskinner38]

Thanks... Now that make sense.

 

[BCXJ90]

My death wobble experience was very similar. I would get to 30mph and hit a tiny bump or turn the wheel the wrong way and my jeep would go crazy. I would have to pull over on the side of the road to get it to stop. I drove it 1500 miles from Missouri to here with no problems and then 2 months later it does this. My brother had just added more lift to the front so he thought it was the control arms, but replacing them didn't help. I basicly had to just start doing stuff to it and see what happened. Had an alignment done, replaced the shocks, bought a heavy duty steering stabilizer, replaced the tie rod ends and the track bar, and rotated the tires. I finally replaced the tires and it stopped. A few months ago it started up again and I ended up replacing both front shocks and the track bar.... again. They were not installed correctly it appeared. Ridiculous.