Vincenza V

I saw this paragraph on a website for JK's. Being we have the same front axle, I think some/all of this knowledge carries over.

Here the paragraph, the ONLY thing I care about is highlighted in blue:
ARB's Old Man Emu suspension suits my needs very closely. OME notoriously provides a terrific on- and off-road ride because their Australian engineers design their suspension systems for long-distance overlanding across the Outback where rough, washboarded roads are the norm. I have firsthand experience with OME's springs and shocks on several of my previous 4x4s and can attest to the superior ride they deliver compared to comparable systems. Two of this kit's shortcomings are that it uses offset washers as a band-aid to correct the front axle's caster, and it offers no steering geometry correction so the drag link and track bar will cause the axle to move in a side-to-side motion as the suspension cycles up-and-down. Both of these issues can be corrected with additional aftermarket parts, but I determined another kit to suit my needs even more perfectly.

I am chasing this "axle moving side to side feeling. It sounds like EXACTLY what I am trying to fix.

Is that really what happens if the track bar and drag link are perfectly parallel?

XJlimitedx99

Sorry, but I have no idea what you're asking.

Whenever the suspension cycles up and down, whether it's stock or super modified, the axle moves on the radius of the track bar. That means that as the axle droops it also gets pulled to the drivers side.

The drag link is supposed to be exactly parallel to the track bar so when the axle moves with the track bar the steering moves the exact amount the body moves over the axle. If they were not parallel, the steering would move via the suspension moving up or down. That is referred to as bump steer.

Hope that helped..

Vincenza V

It's more of what I already knew, thank you though!

I am trying to confirm if the side-to-side motion of the axle can be really cause by the non-parallel geometry.

Tsaani97xj

Could you possibly explain the symptom a little more clear?

Side to side axle movement doesnt relate to anything I have heard of or experienced. As stated above though when the axle moves up (suspension compressed) the axle moves toward the passenger side some. When it goes down (uncompresses) it moves toward the drivers side. When the drag link and track bar arent parallel when the axle moves it pulls the steering one way or the other because their arcs are different. Not much else to its geometry.

Vincenza V

The symptoms as simple as I can describe are this:

-Under 30mph, feels fine.

-On hwy, on very smooth bump free sections, I can take my hand off the wheel and it will go straight for a while (1/8 mile maybe)

-On Hwy that has bumps, I am constantly having to counter steer slightly, but noticeably to keep her going straight. She doesn't want to veer out of the lane or anything like that, but instead of the natural counter steering that you don't have to think about-you are VERY aware of the need to do it.

-Each bump on the hwy make the steering wheel want to move in your hand.

Tsaani97xj

That is bump steer. This is caused by the drag link and track bar being not being parallel. Correct that and that goes away. If you look at a lot of the aftermarket track bars that include a new frame side bracket they compensate for the change in lift height by lowering/moving that end. More than one way to fix it just depends on skills budget desire etc

Vincenza V

I have a RC track bar, with drop bracket. I also have the RC DPA. I tried it with and w/o the arm (didn't seem to make a difference either way, so I have the stock DPA on now).

I will have to take a better look at the two.

Just to be clear, I am stringing it up from bolt hole-to-bolt hole right? Don't look at the bend in the track bar and figure that into the parallel thing right?

Thanks for the help!

Tsaani97xj

http://www.quadratec.com/jeep_knowle...article-68.htm

Explained pretty well there. But yes ignore any bends or shape only the mounting points.