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-   -   DW and your Front End. (http://www.jeepforum.com/forum/f96/dw-your-front-end-1608889/)

JTPhoto 09-21-2013 12:11 PM

DW and your Front End.
 
Rather then comment on another thread I have decided to start a new one Re: Front end components and DW specifically trackbars.

Jeep specs. 08 JKU Sahara 3.5" RK front springs the rest of the lift is a TF 2.5" BB with rear factory 59 springs. 35x12.50x17 Pitbull Rockers at 27psi.

I have just recently changed out some front end parts and discovered the following.
Axle side track bar hole wallowed out.
Original SS 145,000klm in great shape.
Original shocks not leaking but tired.

I have yet to experience any type of DW so a sloppy Trackbar is not the major player on DW.
What are your thoughts on this. I run 90% chip and seal back highways at 50mph and they are by no means smooth.

HappyTrails 09-21-2013 12:23 PM

Ball Joints were my culprit for DW. Have you inspected those yet?
I had already replaced the frame side track bar bolt with a proper sized one with the shoulder on it before my DW/Near Death Experience.

As for the title to this thread. I think a better title would have been, "DW and your REAR end" because I needed a pry bar to get the seat cushion out of my posterior after my first experience with DW. :rofl:

JTPhoto 09-21-2013 02:58 PM

Quote:

Originally Posted by HappyTrails
Ball Joints were my culprit for DW. Have you inspected those yet? I had already replaced the frame side track bar bolt with a proper sized one with the shoulder on it before my DW/Near Death Experience. As for the title to this thread. I think a better title would have been, "DW and your REAR end" because I needed a pry bar to get the seat cushion out of my posterior after my first experience with DW. :rofl:

Yup 2 ball joints are toast. 4 new Synergy ones going in soon. Still have all the original CA and Trackbar bolts. Never an issue and never DW. Which leads me to believe that there is an underlying cause of DW that no one has really pinned down yet. Some get it, some do not no matter how worn or new the front end is.

JTPhoto 09-21-2013 05:06 PM

I would also like to add that over the past 38 years I have own a number of 2 and 4wd vehicle with straight axle and even a few straight axle tractors with no suspension only a pivot pin attachment is susceptible to DW.
As for steering stabilizers, up until about 15-20 years ago straight axle vehicles did not come from factory with them and BTW didn't need them. they were an aftermarket item uses on big trucks when big bias ply tires were used. Back in the day when they couldn't balance tires that big.

TheBoss 09-21-2013 05:52 PM

Any number or a combination of loose or worn steering related parts can contribute to death wobble. Pinpointing the single root cause has always been the issue.

You raise an interesting theory having had no issue, but yet have the underlying worn areas most have pinned down as being the cause.

Nsiavosh90 09-21-2013 05:54 PM

Chiming in on ball joints, mine were bad and I noticed because my tires were toed in bad and my tires wore uneven. Heavy wear on the inside and no wear on the outside. Once I replaced ball joints and replaced tre's drag link joints track bar was torqued properly I still had DW. I rotated my tires so the front were even as far as wear from inside and outside and I dropped psi from 40 to 30, and DW has never happened since. I know you said 27 psi which is already low but maybe rotate tires around

SLADE 09-21-2013 06:53 PM

Sometimes it's one component, other times it's a combination. It's allways worn/loose components, alignment issues, out of balance tires, and slop in the steering and suspension.

Getting by with a wollowed out trackbar mount now does not mean it won't be a major contributing factor later. I would not write it off just because you havn't experience DW yet. Wollowed out/loose trackbars have been the major factor before.

JTPhoto 09-21-2013 08:17 PM

If I haven't experienced DW after a 145,000 of rough roads it ain't gonna happen.
I personally think the combination of too high of tire pressure, bad alignment and worn parts are major contributors to DW. Too high of tire pressure being the trigger.
Have you ever tried to bounce a basket ball with not enough air. Same principle, A low pressure tire can absorb a lot of rough road.

HighandLow 09-21-2013 08:21 PM

I'm a total neophyte when it comes to suspension in our jeeps. So let me put in two cents and try and add to the discussion. The Trackbar does what exactly? Allows your steering to remain stable? While all of the other components do their job correctly the trackbar "tracks" and allows for bumps, grooves, ruts, etc supplemental of what the shocks, SS, tires absorb? Then you have your CA's BJ's and I guess tie rods(?) doing their jobs as well. So it seems like it's not the correction, but the over correction of the suspension that causes the DW. So all things being equal, worn out, or brand new it corrects accordingly. When new springs, shocks, TB's CA's BJ's are added, that seems like the X factor of over correction and uncontrolled steering.

JTPhoto 09-21-2013 08:27 PM

Quote:

Originally Posted by Nsiavosh90
I know you said 27 psi which is already low but maybe rotate tires around

My point was I have never had death wobble even with all the worn parts. But I do run 27psi in 35" Pitbulls which are worn perfectly even. Chalk test proved 25-27psi is the best pressure for even wear on these tires. 45,000 KLM on these tires, rotated every 5000klm and tread depth is even across the face.

As your case implies, tire pressure does play a major role in DW.

TheBoss 09-21-2013 08:34 PM

Quote:

Originally Posted by HighandLow (Post 16209321)
I'm a total neophyte when it comes to suspension in our jeeps. So let me put in two cents and try and add to the discussion. The Trackbar does what exactly? Allows your steering to remain stable? While all of the other components do their job correctly the trackbar "tracks" and allows for bumps, grooves, ruts, etc supplemental of what the shocks, SS, tires absorb? Then you have your CA's BJ's and I guess tie rods(?) doing their jobs as well. So it seems like it's not the correction, but the over correction of the suspension that causes the DW. So all things being equal, worn out, or brand new it corrects accordingly. When new springs, shocks, TB's CA's BJ's are added, that seems like the X factor of over correction and uncontrolled steering.

The track bar locates the axle under vehicle without it the axle would shift side to side shearing the control arms eventually. All parts are function together failure of one component eventually fatigues another in the process.

JTPhoto 09-21-2013 08:49 PM

Quote:

Originally Posted by HighandLow
I'm a total neophyte when it comes to suspension in our jeeps. So let me put in two cents and try and add to the discussion. The Trackbar does what exactly? Allows your steering to remain stable? While all of the other components do their job correctly the trackbar "tracks" and allows for bumps, grooves, ruts, etc supplemental of what the shocks, SS, tires absorb? Then you have your CA's BJ's and I guess tie rods(?) doing their jobs as well. So it seems like it's not the correction, but the over correction of the suspension that causes the DW. So all things being equal, worn out, or brand new it corrects accordingly. When new springs, shocks, TB's CA's BJ's are added, that seems like the X factor of over correction and uncontrolled steering.

Really all the track bar does is keep the differential housing centered under the frame, which in turn, as you stated, just keeps the steering components stable, nothing more and that is why leaf sprung vehicles don't have one. CAs align the diff in the frame rails and keep the the driveshafts happy as well as set caster and pinion angle.
DW happens in ALL straight axle vehicles no matter what suspension they have.

SLADE 09-21-2013 09:23 PM

The track bar centers the axle, allows the Jeep to be steered without shifting the axle, and keeps the load from the axle movement off of the steering draglink. As simple as it may seem, keeping the front axle centered is a crucial part of the suspension and steering.

Control arms locate the axle front to rear and keeps the axle from rotating.

Even some leaf sprung vehicles came with trackbars. The trackbars helped control the front axle on leaf sprung vehicles even though they may not have been required. Ford and Jeep both put a trackbar to some of there leaf sprung vehicles. I think the shackles location played a role in the need/use of a trackbar on leaf sprung vehicles.

Just recently, a worn trackbar on a Crew cab Ford F350 was responsible for causing death wobble on the leaf sprung front suspension.

HighandLow 09-21-2013 09:28 PM

Learning as I go here. Right , and right to Boss Slade and JT replies in helping me understand. So, is what I'm theorizing in any way correct? The overcompensation of weaker parts versus the under compensation of the stronger/ newer, is what causes the DW. IE: Introducing aftermarket springs, shocks, adjustable TB's and CA's expose the weaker stock or worn out OEM parts, like BJ's. It's like computational theory, all parts being equal...blah blah.

SLADE 09-21-2013 09:42 PM

Death wobble is caused by loose/worn parts, poor alignment, out of balance tires, and slop in the steering/suspension. ALL loose or worn parts will play a role in death wobble. It can be caused by new and old parts. Some setups can handle more slop than others.


Death wobble is the steering and suspension getting out of sync with each other. When it starts, it resonates and amplifies itself until it is uncontrollable and continues until the out of control movement is stopped.


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