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Setting Adj Trac Bar

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themauler

NAXJA Forum User
Location
Va Beach
NAXJA,

92 XJ/ 4.0 AX15/ dana 30 chry 8.25/ 3.5" short arm lift/ 33s/ OTK steering...

I am looking for some advice about setting an adj trac bar. I have centered the axle measuring equal distances between a spot on top of the tire and the bump stop tube. When I do this I feel I am preloading the trac bar too much since it takes someone to turn the wheel inside the jeep to get the hole to line up with the trac bar bracket. I am using RE HD bracket and double shear trac bar.

When I hit a bit of a bump going about 55mph all hell brakes loose and death wobble feels like it is going to shake the lug nuts off. Do you guys think that all of that preload is unloading when I hit a bump?

Should I try to find an axle position and adjust the trac bar so that there is zero preload on the bar? Also I have realized my rear axle on leaf springs is not centered either :shocked:

TIA Guys

Nick
 
How much difference/turn of the wheel does it take? A little bit is not a big deal. In theory, you should be able to basically bolt it up without more than a touch/tap of a turn.
Pictures of your setup?
Unless you are running the IRO "OTK" steering, you should be running an OTA track bar mount. If you are using stock type trackbar, with the stock axle side mount then there most likely inlies your issue.
The track bar and drag link need to be parallel or +/- a couple degress difference at most.
 
At 3.5" of lift, the track bar and drag link are parallel enough.

Not sure what you are calling pre-load on the track bar. If the axle is centered under the body, and the track bar ends are in good condition, something else steering/suspension is worn, out of adjustment, or damaged and is the cause of the Death Wobble.
 
My angle with the trac bar and drag link are pretty darn close. A short trac bar but there isn't another option unless I want to run something all the way to the C of the axle.



Pre load as there is already a force acting on the bolts and bar. My understanding is that death wobble comes from something loading and unloading force. I didn't have death wobble like this before the OTK swap. Ball joints are not even a year old. I can't seem to remember how my axle was centered before I did the swap but I feel like the axle was not centered perfectly and I could drive down the highway without fear for my life and the other people on the road.
 
It's not really preload. When I undo the track bar my XJ seems to lean to the passenger side. It just takes some coercion to get it in the correct place.
 
id say that the "preload" you are describing is not the issue. ive found that using the power steering to help align the trackbar can be one of the easiest ways to get it bolted up.

something else is causing your issue... hows the alignment?
 
VAhasnoWAVES said:
id say that the "preload" you are describing is not the issue. ive found that using the power steering to help align the trackbar can be one of the easiest ways to get it bolted up.

something else is causing your issue... hows the alignment?
Click to expand...

Alignment has been done with the tape measure at 1/8" toe and another set of hands to help out. Maybe I can increase the toe a little bit more? I adjusted castor to 7* which is almost stock so I know that the camber on the wheels is there to help counter DW. I am not shy of taking it to a shop but I want to make sure my axle is where it needs to be before I spend money on that. I also need to redo my trac bar bracket brace.

But back to the rear axle, I have noticed that the passenger side rear tire is sticking out of the wheel well further than the driver's side tire....
 
themauler said:
Alignment has been done with the tape measure at 1/8" toe and another set of hands to help out. Maybe I can increase the toe a little bit more? I adjusted castor to 7* which is almost stock so I know that the camber on the wheels is there to help counter DW. I am not shy of taking it to a shop but I want to make sure my axle is where it needs to be before I spend money on that. I also need to redo my trac bar bracket brace.

But back to the rear axle, I have noticed that the passenger side rear tire is sticking out of the wheel well further than the driver's side tire....
Click to expand...

I can only think of two things that could cause the rear axle issues but I suspect there are more. Were your spring perches knocked off on the rear and rotated or replaced with u-bolt eliminators? If so, are you certain they are in the correct place?
Do you know if your XJ has been in an accident or wheeled hard enough to tweak the 'frame' enough to push the right rear out a bit?

For the DW, what is the angle from bolt to bolt. The meat of the track bar looks parallel to the drag link but the eye to eye looks off. How did it handle when you didn't have it centered? I centered my axle after I got it aligned and I've been searching for my lost road manners ever since. I may just take it back and have them center it at the alignment shop since it would be more precise anyway and then I can work on cutting my c's and getting my caster and pinion angles I want.
 
Last edited:
dan1977p said:
I can only think of two things that could cause the rear axle issues but I suspect there are more. Were your spring perches knocked off on the rear and rotated or replaced with u-bolt eliminators? If so, are you certain they are in the correct place?
Do you know if your XJ has been in an accident or wheeled hard enough to tweak the 'frame' enough to push the right rear out a bit?

For the DW, what is the angle from bolt to bolt. The meat of the track bar looks parallel to the drag link but the eye to eye looks off. How did it handle when you didn't have it centered? I centered my axle after I got it aligned and I've been searching for my lost road manners ever since. I may just take it back and have them center it at the alignment shop since it would be more precise anyway and then I can work on cutting my c's and getting my caster and pinion angles I want.
Click to expand...

I will be addressing the angle difference between the drag link and trac bar with a ZJ pitman arm which should get the angle closer if not exact.

Not centered I was able to drive on the highway bumps and all no issues. I did have a developing death wobble/shimmy but that was from a suspect worn out drag link that was 23 years old and my castor angle of about 5* I ultimately did the OTK steering instead of replacing my steering with another stock design.

As for the rear axle there has never been any sort of accident and I have wheeled this XJ for about 5 years so the possibility of frame warping with no frame stiffeners is there. I do know the bushings in the rear of the springs are shot so maybe they have let the axle shift a little bit. I might try to reset the rear axle by loosening the ubolts and see if it goes back to center. Gosh it sucks to have things get worse after an expected upgrade :banghead:
 
I know the feeling. I bought my rig with the expectation of fixing the known issues and wheeling it. Every time I fix something, something else downstream that is OE breaks.

On a side note, I notice you are in VB. I was born and raised there but never got into wheeling until I moved to Utah 'cause you can only drive the beaches in Corolla so many times. Do you wheel in the George Washington national forest?
 
dan1977p said:
I know the feeling. I bought my rig with the expectation of fixing the known issues and wheeling it. Every time I fix something, something else downstream that is OE breaks.

On a side note, I notice you are in VB. I was born and raised there but never got into wheeling until I moved to Utah 'cause you can only drive the beaches in Corolla so many times. Do you wheel in the George Washington national forest?
Click to expand...

Yes Potts Mountain is the closest place. Very scenic trail riding. Nothing compared to Utah though (jealous). But I have done most stuff in NC/VA/KY. Still need to get out to TN and Rausch Creek.

Back to tech, it is a hard thing to swallow after the first hopefully successful test ride and shit hits the fan. I am hoping minimizing any bumpsteer and finding the sweet spot location for the axle will get me back to a worry free ride.
 
garr said:
+1, Check everything, Tires, tie rods, ball joints, wheel bearings, control arm bushings, track bar mounting holes, everything; any play in any of these things can cause death wobble.
Click to expand...

this.

non-matching drag link/track bar angles will cause bump steer, but should not be the cause of death wobble. check everyhting else. even worn UCA bushings have been known to cause wobble.
 
Is your frame side track bar bracket welded on or bolted on? Are the holes slotted or otherwise wallowed out? I found that even the slightest movement here would induce death wobble, so I welded mine this time around.
 
paddlernate said:
Is your frame side track bar bracket welded on or bolted on? Are the holes slotted or otherwise wallowed out? I found that even the slightest movement here would induce death wobble, so I welded mine this time around.
Click to expand...

It is bolted. The bracket isn't even more than 4 months old but that doesn't mean the hole on the unibody aren't wallowed. I would weld it but I would rather do stiffeners before permanently joining it to the jeep. I will work on altering my bracket brace as the OTA trac bar mount moved my trac bar into where the brace was.

Maybe that will help keep things tied in better since the RE bracket doesn't sit quite flush on the rail.
 
VAhasnoWAVES said:
you can stitch weld it in a manner that can be easily cut off when the time for stiffeners comes.

i grew up in VB as well. moved in 2010.
Click to expand...


Modified my original trac bar bracket. I saw my old drag link sitting in the corner and figured the bend in end could be used to help clear the trac bar.





 
Having that brace will do wonders. I never could make the RE joint on the track bar last though. That caused me death wobble. Heim joints fixed it for good. Have someone turn the wheel back and forth a little and look, listen, and feel for clunks
 
1990JEEPXJ said:
Having that brace will do wonders. I never could make the RE joint on the track bar last though. That caused me death wobble. Heim joints fixed it for good. Have someone turn the wheel back and forth a little and look, listen, and feel for clunks
Click to expand...

Luckily this trac bar doesn't have more than 3000 miles on it. I will absolutely be looking out for a worn out bushing in the future and maybe buy a 5/8 heim for it when it does go :explosion
 
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