Wandering and darting steering

[Cpark0402]

I see a lot of topics on the idea of wandering and darting on the TJ. I am having this very issue. My question is how can I tell if the wander and darting is from the front end or the rear end when driving it? My jeep when it hits about 50 mph feels like I am going to roll it going down a straight away. I don’t have a starting point of this issue. I purchased the jeep with a 4 inch lift in the back and best I can tell a 5 or more lift in the front(pro comp). I have pretty much replaced every component on the front end. Even going back to the original pitman arm(to make steering and track bar parallel)and new steering box. New ball joints, adjustable control arms, adjustable track bar, new sway bar bushings. I had a new set of tires and wheels put on it and an alignment done. Also a dual shock steering dampener(which did nothing) . I have not put new shocks On it yet as I don’t see how they factor in on a straight away going down the highway.
So I am now venturing on replacing the rear end components to resolve this issue. But while I wait for parts delivery. I am wondering if there is a way to tell of the wander/darting is coming from the backend vs the front. I honestly can’t say when it starts to happen like if I give it gas etc. but I certainly don’t see any difference if I brake or hit bumps in the road. So other then keep buying new parts. I am grasping at ideas how to make this thing drivable. At the moment it’s literally scary to drive and the shop that put my tires on couldn’t find anything wrong with my suspension. But they could clearly feel the wander when they drove it.
Also I am not a mechanic but I am mechanically inclined. So feel free to tell me I am ignorant and what I should do to fix this thing. I have heard of camber and caster adjustments or adjusting the toe(this is all Greek to me) so help me OB1.
Also if it helps. If I jack up the rear of the Jeep where the back suspension hangs. And spin the rear wheel while the opposite wheels spins the opposite direction then quickly reverse the spin. I can visibly see the rear axle yoke drop or rise about 1/2 inch when forcing the switch in direction. But I don’t think this in itself would cause a wander or darting. I would suspect I would need to see there rear axle move forward or back on one side or the other.

 

[Juggernaut]

What tire size and pressure?

 

[davidgoodman]

I posted that mine was doing this and found the final solution a couple days ago. What ultimately fixed mine was a steering gearbox. And yes, both the front and rear suspension components, steering linkage, ball joints and track bars all have to be without play.

 

[cpwolf]

I'll give my .02 on this, as I have a 2005 TJ and a 2008 JK and BOTH had these kinds of issues.

On the TJ like you have, I would say if you don't know Toe In and Caster, then you need to get to know it.

@Jerry Bransford posted somewhere on How To Align at home. I used 2 square tube aluminum, 2 tape measures and followed the directions, marked up with Sharpie etc, and have the toe in perfect. Write up is easy to find, but put front on jack stands, take off tires, then clamp to the rotors on both sides and start measuring and adjusting. Get it exact.

Then Caster. You've done a lot, and that's a lot of lift, when it goes up, the relationships change as they "hang" to use a slang. I put a magnetic angle measure on top of the ball joints on each side, and measured to get it in range...actually a touch on the high end of in range. This made a MASSIVe difference. One way to know on this, if you turn the wheel while driving, does it return to straight on its own? If not, Caster. These both cost little or nothing to get adjusted and fixed, and you can do them in your garage.

You said you went back to a stock pittman arm, I had to replace the drop arm PO put on, and return to stock. Also, do some measurements, is everything that you can control with the adjustable Track Bar, Control Arms, is everything where it should be? You can measure all this at home by yourself or pay an alignment shop, but I measured it etc.

Lastly, as I see Blaine say a lot here....is everything torque'd to spec? Not over, not under, if you have to over or under......something is done wrong. Is everything tight? Put the front on jack stands on the axle, start it, and have someone go back and forth. HARD with the steering, and look at every joint...all of them. and see if there is anything loose. All my research, I've seen 4 or 5 threads that argue with Blaine..."All IS tight" then take it to him and ooops, something aint' tight.

All of those things can be done and checked before throwing any more parts that I can see.

 

[cpwolf]

On Rear end, only question I have.....how are your bushings? Control arm, track bar, sway bar.

Again, stuff that is loose is not good. My personal experience was wasted CA bushings, and the ass end felt like it was sliding around underneath me on turns, but it didn't cause the darting on straight aways.

 

[Grant Lasson]

I eventually got mine under control thanks to help from the forum @mrblaine and @BuildBreakRepeat. It took time, money, and patience. I recommend a layered approach in which the simplest and least expensive things are checked first. In my case, the PO installed a highly modified suspension (e.g., long arm kit, crossover steering). The PO had toed the front tires in excessively to make it easier to drive straight. However, it also made the steering sluggish in the center (i.e., dead spot) so that it wandered. When the correct toe-in was adjusted, the steering became "darty" and had extensive bump steer. I then removed the drop track bar mount and installed the rockjock adjustable track bar. I also installed the rockjock heavy duty steering and tie rod. Was the axle centered and square to the frame? No--they required adjustment. Better but not good enough. I installed the PSC steering box. That was a major step up in steering quality. I used a BBK install as an opportunity for new ball joints and unit bearings.

My point is that the steering is a complex system of interrelationships. Solving it might involve unraveling problems in several steps. Some steps may take it backward but represent a step forward ultimately. If I had not reset the toe correctly, I wouldn't have discovered the problems it was hiding. Driving it then was a wild and uncomfortable experience. It was tempting to reset the toe to what it was previously but I resisted and worked systematically towards a total system solution.

It also took iteration. It was worth the time to work out a system for measuring toe-in, axle centering, and axle location relative to the frame as I had to use these systems several times. I can share how I did them but there are quite a few good threads on these topics so I won't go into them unless requested. Other people are much more experienced and expert than I am.

Ultimately, I have the steering I wanted. It's sensitive, accurate and predictable. Jeep goes straight down the road. I'll mention one more thing--the Jeep tracks grooves in asphalt. I believe that is due to the tire size (35x12.5x15).