Incurable Death Wobble Need Help

[onlyinajeep726]

The other thing that concerns me is the readings for the rear, its a straight axle how could the toe be out like it shows on the print out.

 

^{Damn, good eye!}

[Wrz]

The heck is THAT broken bracket attached to?!?!?!?!?!?

Broken bracket? Where do you see a broken one?

[Wrz]

 

Looks like a drop pitman arm with a stock track bar mount. They need to be dropped the same amount. If you drop one the other must be dropped too.

At 4.5", 7* of caster is preferred.

 

Yeah Bo, thinking the same. You need the track bar and drag link as close to parallel as possible as in the pic below. You don't have a pic wide enough to see the total relationship. The geometry looks wrong from what I can see due to the dropped Pitman. 

 

That's actually a stock pitman arm, but wouldn't a drop pitman arm make them more parallel? As far as the axle side what would make them more parallel, I don't think I could turn the trackbar so the hump is facing up.

[Wrz]

The bends on the trac bar make it look right out ... but it doesn't look that far off overall .. you have to go from mount to mount, not the actual visual comparison.

The inverted T steering arangement likely isn't helping.

 

Having chased death wobble all over hell and back on my XJ ... it could be anywhere. It all adds up. The extra control arm angles due to lifting compound and accelerate the issue.

 

A trac bar alone won't do it, but anything else out with a tracbar issue will. Have you looked atbthe upper control arms? If they are worn they will cause enough axle shift to start deathwobble.

Lower your tire pressure as mentioned ... at 35psi the tires will also feel twitchy enough to start an episode. Try 30 or even 28psi ... heck I run 26psi in my 35's on my XJ.

In the end I cured my death wobble with a homebrew long arm 3 link conversion. The biggest change ... lower control arm operating angles and new beefire control arm joints (all are large RE cartridge joints). When we tore it apart we found worn upper arm bushings and a flexing trac bar mount. All added up to wicked ... crap your pants death wobble.

On the other hand ... when I bought my MJ the tracbar had 1/2" of pay in the balljoint end ... and not a single hint of deathwobble up past 140 km/h ... the XJ was a death wobble king at 80km/h ...

Yeah both upper control arms are new and are tight, when I swap my tires around tomorrow ill lower all the psi to 32 and lower more if not improved. I was looking at long arm kits, but would hate to break the bank if its not needed.

[Wrz]

If the readings are true that he gave you then it seems like the axle is twisted. If you look at the control arm mount pictures one side only has one shim and the other has a stack of them. My first recommendation would be take it to a different larger auto shop to have the tires balanced and alignment checked. The other thing that concerns me is the readings for the rear, its a straight axle how could the toe be out like it shows on the print out.

I found a shop that only builds and works on jeeps somewhat locally, I'm going to see if I can make an appointment this week, I noticed one had more shims then the other which didn't make sense, I'm going to have to take some measurements after work to see if the axle is actually twisted.

[HOrnbrod]

 

 

Looks like a drop pitman arm with a stock track bar mount. They need to be dropped the same amount. If you drop one the other must be dropped too.

At 4.5", 7* of caster is preferred.

Yeah Bo, thinking the same. You need the track bar and drag link as close to parallel as possible as in the pic below. You don't have a pic wide enough to see the total relationship. The geometry looks wrong from what I can see due to the dropped Pitman. 

 

That's actually a stock pitman arm, but wouldn't a drop pitman arm make them more parallel? As far as the axle side what would make them more parallel, I don't think I could turn the trackbar so the hump is facing up.

 

You need a pic showing the whole drag link and track bar. Then in your favorite editor draw a straight line from the center of the mounting point to the center of the opposite mounting point. As above. 

[Wrz]

 

 

 

Looks like a drop pitman arm with a stock track bar mount. They need to be dropped the same amount. If you drop one the other must be dropped too.

At 4.5", 7* of caster is preferred.

 

Yeah Bo, thinking the same. You need the track bar and drag link as close to parallel as possible as in the pic below. You don't have a pic wide enough to see the total relationship. The geometry looks wrong from what I can see due to the dropped Pitman. 

 

That's actually a stock pitman arm, but wouldn't a drop pitman arm make them more parallel? As far as the axle side what would make them more parallel, I don't think I could turn the trackbar so the hump is facing up.

You need a pic showing the whole drag link and track bar. Then in your favorite editor draw a straight line from the center of the mounting point to the center of the opposite mounting point. As above.

Ill take a new one tomorrow when it's light out, sorry if this is a stupid question, but when you say parallel do you mean with track bar and linkage side by side, or above one another? If that's the case a aftermarket trackbar mount should do the trick right?

[HOrnbrod]

See the two red lines on the pic above? You can see that the track bar and drag link are very close to parallel.

 

Also, do you have an angle finder? Compare the right and left readings on the flat top of the upper ball joints. This will be very close to your actual caster reading.

 

http://comancheclub.com/topic/39260-shadetree-caster/?hl=caster&do=findComment&comment=395104

[Wrz]

See the two red lines on the pic above? You can see that the track bar and drag link are very close to parallel.

 

Also, do you have an angle finder? Compare the right and left readings on the flat top of the upper ball joints. This will be very close to your actual caster reading.

 

http://comancheclub.com/topic/39260-shadetree-caster/?hl=caster&do=findComment&comment=395104

Thanks I understand it more now, I don't own a angle finder but will get one to see what angles I'm achually at

[Incommando]

Caster or track bar bushing/bracket is loose.

 

On my last XJ the track bar bracket came a bit loose from the frame and I mean barely.  I had death wobble like mad.  Welded the bracket to the frame, problem solved.

THIS! And not only does the bracket loosen but the mounting hole in the bracket wobbles out where the tie rod end goes into the frame-side mount . This can be kind of hard to detect with the weight on the vehicle. I have found this to be the cause of more than one case of "incurable" DW and so many do not even know to check for it.

 

As mentioned steering stabilizers do nothing to prevent DW. They help to mask it until it becomes too severe or the stabilizer wears out. 

 

I must disagree with the unbalanced tires being the only cause of DW. Next time you have a vehicle with DW swap tires with one that does not and see if the DW goes away or if the DW transfers to the other vehicle when you transfer the tires. I have done this to disprove the tire balance story to someone at one point. Tire balance will not fix a wobbled out track bar mount, for example. Tire balance may contribute to DW but is not the only cause.

 

Something as extreme as golf balls in a tire should be reserved as a last resort for truly large tires. Balancing of most good tires up to 37" or so is easily obtained by using good machine and a good shop.  265/75/r16 (32x10.5 +/-)is a very standard size anymore and modern balancing does a fine job with them. Heck the SO's '14 traverse has nearly that large of tire stock ( 255/55/r20 = 31.5x10 +/- ) and they balance just fine. Do you think GM is putting golf balls into their Traverse tires?

[Timeless]

The drag link and track bar angles will not cause death wobble, but will cause bump steer which could in turn cause death wobble.  Death wobble is largely because suspension parts are loose and "give".  The inverted T steering set up set up should help prevent it provided the tie rod ends are good.

 

I would suggest lifting the front end off the ground, taking weight off the front suspension and trying to move the front end in every way possible other than up and down.  Even if a bolt is slightly loose, you can get death wobble.

 

But first fix your caster.

[Eagle]

I must disagree with the unbalanced tires being the only cause of DW. Next time you have a vehicle with DW swap tires with one that does not and see if the DW goes away or if the DW transfers to the other vehicle when you transfer the tires. I have done this to disprove the tire balance story to someone at one point. Tire balance will not fix a wobbled out track bar mount, for example. Tire balance may contribute to DW but is not the only cause.

Disagree all you want, but tire imbalance is what causes death wobble. In fact (as I have posted here many times in the past, I HAVE done what you suggest. When I experienced death wobble in my '88 MJ, I swapped to a different set of tires ... and the death wobble went away.

 

Obviously tire balance will not fix a wallowed out track bar bracket, but a wallowed out track bar bracket also does not cause death wobble. It cause loose, sloppy steering.

[HOrnbrod]

I don't think that statements llike (fill in the blank) is the cause of death wobble, or (fill it in again) can not cause death wobble are ever correct. There is never a single cause or non-cause. Tire balance, loose track bar mount, bump steer, bad control arm bushings, caster angle, etc. etc. etc. are all contributors that combine to initiate and sustain the steering system oscillations known as death wobble. Usually when you find one symptom, if you look hard enough you'll find another.

[Eagle]

I don't think that statements llike (fill in the blank) is the cause of death wobble, or (fill it in again) can not cause death wobble are ever correct. There is never a single cause or non-cause. Tire balance, loose track bar mount, bump steer, bad control arm bushings, caster angle, etc. etc. etc. are all contributors that combine to initiate and sustain the steering system oscillations known as death wobble. Usually when you find one symptom, if you look hard enough you'll find another.

The problem is, too often the discussion of death wobble conflates cause with effect. Things like sloppy tie rod ends and loose track bar brackets certainly are less effective at combating death wobble than new, tight parts -- but they can't cause death wobble. Death wobble is, after all, wobble. More to the point, it's wobble that starts in one wheel and is then transmitted to the other wheel in a constantly self-reinforcing harmonic reaction, which is why once it begins the amplitude escalates and the only way to stop it is to stop the vehicle. But something has to start the wheel(s) wobbling in the first place. That's the "cause."

 

I commuted to and from work for an entire winter in my '88 Cherokee with a track bar that was so bad I had nearly a quarter of a turn of free play in the steering wheel. Keeping it in one lane took a lot of concentration, but there was never even a hint of death wobble.

 

A track bar can't make a wheel wobble, therefore it can't cause death wobble.

[Wrz]

Empty Post

[Eagle]

You have an adjustable track bar. That's what you use to center your axle.

 

After the axle has been centered, you then have to adjust the toe-in and then center the steering wheel. To be honest, the shop that did the alignment should have centered the axle first, before doing anything else.

[Wrz]

Yeah they definitely dropped the ball, when it gets a few degrees warmer I'm going to center everything and check all my angles

[dave92cherokee]

 

 

 

 

 

In those pictures you're throwing yourself off in getting the lineup of the steering versus the track bar. When editing the pic you want do draw a line from the center of mount to center of mount, not from grease zerk to random point. When tying off the string you went from the zerk to the bolt on both of them which is going to throw it off. For what you have going on with the angles I would look at a drop pitman arm but just a small drop of like an inch or so. If you drop the frame side of the track bar then it will create a bigger V shape between the two. This should help with the bump steer you're experiencing. As for the death wobble I would start by getting the tires re-balanced by a different shop, I would take out all shims on both sides and throw them in the glove box and have them do an alignment again. Making sure to tell them what the jeep recommended settings are then having the shims in the box if so needed to get there. This way when they have the before and after measurements you should be able to see a big change as pulling the shims will increase it greatly then they would have to add shims back in (should be same on both sides if axle isn't twisted) to get it down to the recommended setting.

[Wrz]

 

In those pictures you're throwing yourself off in getting the lineup of the steering versus the track bar. When editing the pic you want do draw a line from the center of mount to center of mount, not from grease zerk to random point. When tying off the string you went from the zerk to the bolt on both of them which is going to throw it off. For what you have going on with the angles I would look at a drop pitman arm but just a small drop of like an inch or so. If you drop the frame side of the track bar then it will create a bigger V shape between the two. This should help with the bump steer you're experiencing. As for the death wobble I would start by getting the tires re-balanced by a different shop, I would take out all shims on both sides and throw them in the glove box and have them do an alignment again. Making sure to tell them what the jeep recommended settings are then having the shims in the box if so needed to get there. This way when they have the before and after measurements you should be able to see a big change as pulling the shims will increase it greatly then they would have to add shims back in (should be same on both sides if axle isn't twisted) to get it down to the recommended setting.

Ok that makes scenes, yeah the zerk was the easier point to tie to on both, but I see what your saying, as far as the drop pitman arm, I thought you shouldn't do one without the other?

[HOrnbrod]

Ok that makes scenes, yeah the zerk was the easier point to tie to on both, but I see what your saying, as far as the drop pitman arm, I thought you shouldn't do one without the other?

Think about it. If you use a drop Pitman arm to drop the draglink into parallel with the track bar, then dropped the track bar they wouldn't be parallel anymore. The picture below sure looks like a dropped Pitman arm, like maybe a 1" dropped arm from a ZJ, would really help line things up. But that may be only because of the parallax angle the picture was shot from. The pic should be from the front looking directly to the rear, not from the side.

 

[Wrz]

Just went outside and got some part numbers off the arm, it's a stock cherokee arm part number 8952000615T. So a drop trackbar bracket and a 2" drop pitman arm should get them pretty close to parallel. Or I could just get a zj one with should drop it between 3/4-1"

I know I'm over thinking this and sorry if I keep asking the same question just in a different way. Still doing a lot of reading up so I can understand everything,

[HOrnbrod]

Before doing that, grab a front shot showing the whole track bar and drag link end-to-end with the wheels pointed straight ahead.

[Wrz]

Ok sounds good, going to see if I can get a clear picture now if not I will tomorrow

[Wrz]

 

 

 

 

[Timeless]

Looks really darn close to perfectly parallel to me...