Steering problem question

[Diesel]

Hey ya'll, I have been battling a bout with re-occuring death wobble for about the last year. I have replaced basically everything that can cause it and have upgraded to a cross-over steering set-up above the steering arms on the knuckles and raised the trac-bar to match. Wheel bearings are good, castor is good, allignment is good, all TRE's are good, trac-bar good, ball joints good, suspension bushings good, and I still get the goshdarned wobbles if I hit a sharp bump going 45 or so and above. Could all the wobble in the past messed up my steering box and now that could be the cause? I am running out of ideas, patience, and money, so any help would be greatly appreciated! Also, besides from doing the jiggle and inspect method of checking ball joints and wheel bearings?
Bryan

 

[SV1CEC]

Hey ya'll, I have been battling a bout with re-occuring death wobble for about the last year. I have replaced basically everything that can cause it and have upgraded to a cross-over steering set-up above the steering arms on the knuckles and raised the trac-bar to match. Wheel bearings are good, castor is good, allignment is good, all TRE's are good, trac-bar good, ball joints good, suspension bushings good, and I still get the goshdarned wobbles if I hit a sharp bump going 45 or so and above. Could all the wobble in the past messed up my steering box and now that could be the cause? I am running out of ideas, patience, and money, so any help would be greatly appreciated! Also, besides from doing the jiggle and inspect method of checking ball joints and wheel bearings?
Bryan

Although I didn't had wobble, I had terrible steering since the day I installed my Rusty's 4.5" lift. After 3-4 alignments and three pitman arms, the problem was traced to :

1. TRE on the frame end of the track bar (replaced with a bushing end and frame). That solved almost 80% of my problem.

2. New steering box, to eliminate a wondering tendency and unknown straight-ahead position.

After six months of frustration, I have a decent steering again.

My 2 Eurocents only

Rgds

 

[lndrvrxj]

How many miles do you have on your tires. i was told that if your tires were worn more on the outside than in or vise, that could be one of the problems. I have been have the same problem as you, hopefully i am going to be getting new tires soon. Then i will be able to tell if that was the problem or not

:dunno:

 

[SV1CEC]

How many miles do you have on your tires. i was told that if your tires were worn more on the outside than in or vise, that could be one of the problems. I have been have the same problem as you, hopefully i am going to be getting new tires soon. Then i will be able to tell if that was the problem or not

:dunno:

I suppose you are asking Diesel, but since this was something I left out too, my BFG MT are brand new, installed them right after the lift.

Rgds

 

[jalehman]

One of my friends who does alignments at Les Schwab swears up and down that backing off the castor will cure death wobble. He says that the chronic cases that they have had were all cured by running around 4 degrees castor. His own personal rig is a grand cherokee with about 6" of lift. I don't know for sure but that is what he said.

My neighbors cherokee has had death wobble ever since he lifted it. Brand new 35" bfgs that he has had balanced twice to double check. Toe in is right at 1/16" in. Everything in the front end is completely tight and in great condition. The only thing is, he is running about 8 degrees castor. He doesn't want to decrease the castor because he felt the death wobble was a little worse at 6 degrees. I thought that it was lethal at both settings. Maybe I'll be able to talk him into 4 degrees castor because I want to test this theory.

I've only had death wobble once when I swapped tie rods and had too much toe in. My castor has always been right around 4 degrees.

 

[watson]

When I first got the dw with my 5" lift, my castor was around 6 degrees. I got it down to about 1 degree and it went away. Maybe a little overkill but it worked. Control arm drop brackets or long-arms I think are the best way to get rid of dw. That worked for me once I went over 8" of lift.

 

[cagedxj]

You might want to check out your track bar and mount for flex if the caster dosent pan out for ya. Good Luck

 

[MaXJohnson]

Death wobble consists of two motions; a simultaneous shimmy of both front tires and a fluttering(like a bowtie), up and down motion of the axle. Each of these motions will oscillate at a certain natural frequency unless supressed by outside forces. When the natural frequencies of the two motions coincide, death wobble can occur. The natural frequency is a function of weight and spring rate and will usually happen around the same speed for a given design. Heavier axles and tires with soft springs and low air pressures will tend to experience death wobble at lower speeds; lighter weight and stiffer springs rates, just the opposite. As an example, D-60's and 39.5's see deathwobble in the 30-40 MPH range while D-30's and 33's might experience it in the upper 40 to 50 MPH speeds.

You affect the weight involved by changing axles, wheels and tires. You affect the spring rate by changing springs, anti-roll bars, suspension compliance, air pressure, sidewall stiffness, tread flex/squirm, etc. Various combinations of these and other factors such as wheel offset can alter the natural frequencies of the two oscillating motions to a point where they are close enough together to feed on each other. Then all it takes is some triggering energy from an out of balance tire or single wheel bump/dip event to set things off. If the front end goes nuts every time you drive it, tire balance is the trigger.

Other factors in the front suspension and steering dampen these oscillations. Steering stabilizers, correct castor, tight drag link ends and tight steering box all help to keep things under control. Track bar bushings that locate the axle side-to-side can be part of the problem. This includes steep track bar and drag link angles.

What is your castor set at? IMO, 6° seems to be a pretty good target. Try changing your air pressure up or down and see if things improve. Try a different size tire or wheel offset as an experiment.

HTH

 

[xj92]

I had DW when I started out with 4.5" of lift. I tried several things, but the cure for mine was getting rid of the stock LCA's and putting on the solid skyjacker ones that came with the lift. Different stuff works for different cases of DW, but that's one more thing to check.

 

[Diesel]

Thanks for all your replys! Well, I do have RE drop brackets, so my suspension arm angles are very good, I raised the trac-bar on the axle end so that it is pretty much perfectly parralell to the drag link, all the steering TREs are 3/4 ton and brand new. I will try and lower the castor, check all the steering box mounting bolts and check the bolt on top of the box that adjusts the amount of play and see what happens. The tires are pretty old but have good tread left and have been rotated and kept balenced, so have worn evenly. It is driving me crazy so hopefully something will happen!

 

[Eagle]

I will try and lower the castor ...

Whoa, pardner. Go back and read the thread again. At least two very knowledgeable people just told you that caster should be around 6 degrees. We have had many long, involved threads on this forum about death wobble, and one of the few constants we see is that increasing caster seems to alleviate death wobble. Reducing caster does not.

The only reason not to run even more caster than 6 degrees is that you have a solid axle, and changing the caster also changes the front pinion angle. Finding a compromise that yields decent steering and no death wobble while not killing the u-joint is alwys a hit-and-miss proposition, but nobody on these forums has ever (before now) suggested that reducing caster might help cure death wobble.

I respectfully suggest that you go back and read MaXJohnson's post again -- several times.

 

[Diesel]

Right now my castor is about 7-8* or so, so maybe dropping it down to six might help. In my past experience, lowering the castor did help with death wobble but now I have a whole different steering set-up so I figure that trying again with a more "factory spec" figure might be the ticket, but maybe not. My theory to why lowering castor helps in some circumstances is that when or if things start to flutter back and forth, having little castor makes it less violent since the point of castor is to give the wheels the tendency to go straight ahead and so the castor causes sort of an over correction condition. Well, like I said it is a theory, but maybe science as well. But, I think that it is a band-aid regardless of why it may help. If something is not right, than lessening the castor to help isn't fixing the problem, it is just changing the situation so the problem isn't as severe, or as in my case, hidden until it finds another means to rear its ugly head. Maybe I have too much castor, maybe lowering down to 6 degrees might help, but I don't think that my DW is caused by too little or too much castor, castor just effects where and how intense it will occure. I still appreciate all the help and am up to more discussion. My biggest hang-up is that I have done bassically everything to solve it, and the only things left are the steering box itself and the possibility that the ball joints and the wheel bearings are undetectibly worn to the human eye, but still worn enough to cause problems. Maybe one thing that might be a clue to some of you super slueths out there is after one particullarly violent bout of the wobbles, there was a weird noise coming from the engine compartment, very possible the steering box or pump. By the time I opened the hood, the noise had stopped so I couldn't see for sure. Sorry all these have been so long, but I really need to fix this for a trip to the 'con in mid June and also so I don't loose all self esteem and consider myself a failed jeep owner.

 

[SV1CEC]

Failed Jeep owner?

Only if you stop working on your truck.

It took me six months to solve my dreadfull steering problem, but finally I did it, and I am very happy now. This feeling is what Jeeps are all about, self-accomplishement, when you finally arrive at a solution.

Until then, keep searching!

Rgds

 

[jalehman]

Eagle,
I have never heard that increasing castor gets rid of death wobble. Increasing castor just increases the straight line stability and return to center feel. It also increases the steering bind when turning. If your rig drives fine at 4 degrees castor like mine does, why increase it to 6? 6 degrees castor is the baseline figure to shoot for if the rig is driving bad or has driveline vibrations, not death wobble. International Scouts have always come from the factory with around 0 degrees castor. I bet the death wobble on those suckers is just awful..... yeah right.

 

[XJoachim]

I run about 4.5" castor with a long arm setup at about 10" of lift in front and in have no sign of death wobble at all. But if just one bolt is not tighten to specs i feel it in my steering wheel with the tendency to wobble what means to me "time for inspection" of the front end.

Sometimes it's just a wheel out of balance and sometimes a worn bushing. To find the right adjustment do like MaxJohnson advised, got to a 6° castor and play around with tire pressure if everythings alright. 8° castor is definitely too much.

 

[Eagle]

Eagle,
I have never heard that increasing castor gets rid of death wobble. Increasing castor just increases the straight line stability and return to center feel. ... International Scouts have always come from the factory with around 0 degrees castor. I bet the death wobble on those suckers is just awful..... yeah right.

If you haven't heard this, then you haven't been with long enough to participate in some of the very long and involved discussions we have had about what "causes" death wobble and what "fixes" it. As I commented, out of all those discussions one of the very few constants was that almost universally people reported increased caster either eliminated or reduced death wobble.

The Scout is not applicable. The Scout dates to a time when virtually every vehicle Detroit produced had zero caster, and the reason was that nearly every vehicle had manual steering, and increased caster means increased steering effort.

Death wobble is only a probelm when it occurs. There could be thousands of Scouts that never experienced it, but that doesn't mean zero degrees of caster is the reason why they didn't. FWIW, my one and only experience of real death wobble was in a totally stock 1999 Grand Cherokee WJ, on a smooth state highway in New Hampshire. Out of about 15,000 miles that I drove the vehicle, it was the only time I experienced death wobble. What set it off was applying the brakes while going downhill. Sounds rather trivial, but I had the famous Jeep warped rotors and that's all it took. However, the same rotors never set off death wobble any other time.

There is no single cause for DW and no single solution. However, based on real world reports on the forums, I stand by my statement that one of the very few constants we have seen is that increased caster tends to reduce or eliminate death wobble.

 

[MaXJohnson]

... International Scouts have always come from the factory with around 0 degrees castor. I bet the death wobble on those suckers is just awful..... yeah right.

...and I've heard that ignorance is bliss.

Eagle's point about the lack of power steering on the old Scouts is right on. That plus the fact that the design parameters of the Scout front end keep it out of the natural frequency zone that I mentioned. It is when we start modifying our Jeeps with bigger tires, different springs and other suspension/steering parts, less backspacing, etc that death wobble becomes a problem. IMO, Eagles experience in the stock Grand is an isolated case and the only report of death wobble I've ever heard on an unmodified Jeep. Read a few posts on swapping in Scout axles and you'll find that the lack of castor is considered one of the downsides to this axle.

 

[jalehman]

I know that 0 degrees castor is a definite downside. The wandering and feel at the steering wheel would be awful. I was just trying to point out that many Scouts are happily weaving in and out their lanes without death wobble issues. Also, many Scout IIs came with power steering and still had the same castor specs.

I was trying to separate the notion that what causes wandering and decreased steering effort shouldn't be associated with what causes death wobble. In my opinion, they are two complete different problems.

Either way, you would have to rule out any loose suspension bolts, worn joints, toe in/out conditions, and wheel balance issues before you even considered castor. Once all of these are checked and you still have dw and are running 7 to 8* castor, which diesel is, I would highly recommend that you decrease castor. That is the point I was trying to make.

 

[watson]

I was the one who said 1 degree worked for me. I'm wasn't saying he should set his at 1 degree I was just making a point that it isn't always fixed by the textbook solution. All Jeeps react differently. It was just another suggestion if nothing else worked. When I set up my lift (about 5") I was at 6 degrees castor. This was with all brand new suspension, shocks, rusty's tie-rod conversion steering, brand new BFG ATs (31s too, nothing big). I got the full-blown dw. Go about 45 and hit a bump and the tires got to shaking everywhere and bouncing off the ground (could barely keep it in my own lane) and nothing would stop it until I came to a complete stop. I called several suspension manufacturers and they all recommended going higher so I set it to 8 degrees and it was even worse. Wouldn't even have to hit a bump, 45 mph on flat road and start a wobblin. I replaced all the ball-joints, got all new stock steering parts again, sway-bar bushings, bigger steering stab, even a different set of lower control arms. All of this helped a little but not nearly enough. I was almost to the point of taking the whole lift back off. I figured I had nothing to lose and took some shims out and it was about 3 or 4 degrees and it rode way better but still had some shimmy, but not dw. I took all the shims out which put my castor around 1 degree and bingo, no problems anymore. I know, it seemed all wrong to me too, but it worked and I felt SO much safer driving it that way. It was just a suggestion. From reading on here and other forums plus my personal experience with mine and some friend's dw, you can't count out anything.

 

[Rocky]

I have had several small problems with the way my XJ steers after 5 inches and lots of tweaks here and there. Never understood what DW was until two days ago. I was slowing from about 70 mph on a smooth highway with my Dodge dually 4x4, when all of a sudden the wheel was shaking terribly and my employee/passenger's eye's where opened wide. Don't know what the problem is yet but I do know now that what I previously thought was DW in my Jeep wasn't. As the four link design is similar on the front of my truck and everything is stock maybe I'll learn something new. Hope it doesn't happen with 16,000 lbs on the trailer, yikes!