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Old 10-18-2018, 09:10 AM
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Wobble that I beat just came back

I have a 16 JKU with a teraflex 2.5 coil lift. It had a terrible ride and DW with a big bump from the word go, after about a year I chased the issue down to a ovaled hole in the rear track bar relocation bracket. It was tight enough not to clunk or move by hand but was allowing the axle and frame to move side to side a little less than an inch. Removed the bracket, remounted original track bar in the stock location... ride tightened up like new. Did the rear brakes a month or two ago which were about due and just replaced the wheels with AEV savagres and a new set of Wildpeaks in 285/70r17 this week. Not running rear sway bar links for the moment.

The jeep feels 100 times better going down the road and going over bumps, but now I have a whole other wobble. It's triggered by hitting the brakes hard but not with 100% regularity. Maybe half of the time if I apply a good amount of pressure to the brakes rapidly itll feel a little squirrely like it wants to start wobbling, about half of those times it actually does and once it starts it keeps going until I pull over and slow down to about 10mph regardless of brake input.

Everything up front (track bar, tie rod, drag link) all feel tight and without play when I climb under the jeep. The only part that's modified are the sway bar links (are the stock rears) and the tie rod got folded once on a rock and replaced (foolishly) with a crown part, but both rod ends feel good. The front brakes are original, which means poorly lubed from the factory, but only have 45k on them. I can feel a little oscillation in the pedal under light constant braking, but just barely. I'm sure doing front pads and rotors will help, but theres gotta be an underlying issue I'm missing that's making it so prone.

Thoughts?

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Old 10-18-2018, 07:41 PM   #2
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Warped rotors?

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Old 10-18-2018, 10:20 PM
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Rotors was my first thought. That is what it feels like, but its intermittent. If it was a warped rotor I'd feel the shimmy that triggers the DW all the time. Plus, it's rare but It still happens when i hit bumps. I guess this thread will turn into my own discovery journal. I finally found planman's videos and have something to go on


Tomorrows plan is this... front brakes and rotors. It's cheap and the brake pad slides in the rear were rusted when I did those a few thousand ago... if the front slides are rusted they could be binding and have warped a rotor.

I have a track bar bushing kit from rugged ridge that I was going to use on the rear before I realized that the relocation bracket was the problem. I'm going to put it on the front track bar with new 9/16-18 grade 8 bolts and stove or lock nuts.

If I have time, install the new 3" rear sway bar links from rugged ridge. The forums would indicate that they are shorter than they should be and work well for 2.5 (2 inch rear) lifts.

I'll report back what comes of it.
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Old 10-19-2018, 10:18 AM   #4
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I'm very confuzzled... you had death wobble, and repairing the rear track bar fixed it?

DW is not a shimmy or a pulsing when brakes are applied... it is when you hit something (usually off angle) and the front starts oscillating in a feedback loop so violent that it can not be stopped without almost coming to a complete stop. It causes complete loss of steering control. If you have this happening more than once, you likely have extreme damage to the front track bar mounts.

All solid front axles are going to give you a little shake when you hit a bump... that's just the weakness of the design. Are you sure you are dealing with full-scale death wobble? Brake rotors will have nothing to do with DW, but everything to do with a pulsing or shimmying steering wheel when you are stopping. And warped rotors sometimes get worse when they warm up (or cool off) so it can come and go for sure.

The other issue with front-end brake feel after a lift is the geometry has changed on the front control arms. Geometry correction brackets will help reduce the brake-dive, and likewise the weight transfer that is now increasing the load on the front. Adding larger wheels/tires compounds this issue. If you are going to start replacing rotors... think about a big-brake kit.
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Old 10-19-2018, 01:38 PM   #5
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I replaced all the metric bolts on the front and rear track bar with 9/16ths grade 8 shouldered bolts and it made a world of difference in the way the Jeep handles. But, the front track bar mount at the frame has to remain a metric bolt because in 2012 they changed the bushing on that track bar end to a metric size. I replaced the metric fully threaded bolt with a metric shouldered bolt for that position to avoid any damage to the mount. Also, I followed the Synergy recommendations and torqued all the bolts to 135 ft lbs.
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Old 10-19-2018, 02:08 PM
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So to clear up a couple things, it is a genuine death wobble caused by hitting potholes and the like, but more than once hitting the brakes has caused a warped-rotor-like shimmy that has TRIGGERED the death wobble. It's happened twice now and forced me to come to almost a complete stop before it went away. It has absolutely been triggered by bumps and pot-holes also.

Today I replaced the front brakes and rotors just in case. Rotors felt fine and the pads looked great and even, but who knows. I bought some shouldered 9/16-17x3 bolts this morning to swap out the bolts on the track bars front and rear. I've had the rear track bar out but the front for whatever reason I dont have a socket to fit. I suspect its 21mm, I'll have to order one.

I ran out of time before I got to replace the rear track bar bolts, but I did find them to be not that tight at all. While I was back there I reinstalled my rear sway bar links and tightened the track bar bolts. We will see if anything improves on the ride to work tonight, but I'm not expecting much.

What size metric shouldered bolt do I need for the front of the track bar? Will the 9/16-18 bolt work on the axle side? And do I need new bushings or bushing sleeves? I have a rugged ridge poly track bar bushing kit but the sleeves wont past the 9/16 bolt.
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Old 10-19-2018, 06:19 PM   #7
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Have you checked the ball joints? Anything that can allow lateral oscillation can be the cause of DW, so bad ball joints could be the cause, perhaps?


As for the 9/16th bolts, they are a better fit than the 14mm used stock, and many (myself included) replaced the 14mm with 9/16th. At least for OEM track bars.
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Old 10-19-2018, 07:49 PM
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I was referring to 93yjfan above who said that the frame side track bar mount needs the metric bolt still in 2012+ JKs. I dont want issues down the road but I also dont want to drill out the mount on the frame.

I haven't checked the ball joints, I just checked the prices of them. I really dont want that to he the issue but I suppose I should give them the shovel test. I suppose at 40k miles it's at least plausable.
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Old 10-19-2018, 07:55 PM   #9
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I hope they are ok. But it's a cheap & easy check! I don't know about the 2012+, but I have the 9/16" in both ends of my '08 trackbar.
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Old 10-22-2018, 07:52 AM   #10
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I just took the 14mm bolt to the hardware store with me to verify the size I needed. I measured the width of the bracket it went into and then got a few hardened washers to make up the difference if it was to long. I ended up using one on each side of the bolt and then torqued it to 135 ft lbs. I haven't had any issues with the bolts since.
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Old 10-22-2018, 02:32 PM
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Small update. After changing my front brakes and tightening up all the loose bolts I found (mostly rear) I am majoritively wobble free. A couple times I felt a wobble start after hitting a bump just right, but it petered out without launching into a death wobble.

I jacked up the front of the jeep this morning in the garage at work. I moved the tires by hand and used a pry bar to lift up on them, all of the ends and ball joints out front are tight and without play as far as I can tell. That leaves two possibilities... 1 the super minus tie rod (crown replacement, shorter than stock) has enough flex in it to contribute to the problem or, and far more likely, theres a little play in the track bar bushing sleeves. Next pay day I will be grabbing the Northridge grade 8 hardware kit.

I also spoke to a local jeep guy or two who believe that alot of the track bar issues are amplified by the relatively low (more neutral) caster angle. I do remember when I had my post-lift alignment done the shop said caster was within spec but it was a tad under what the jeep builders were telling me minimum negative caster angle should be. The consensus seems to be "it couldn't hurt" to add front adjustable upper control arms and roll the caster back 1 or 1.5 degrees. I wish I kept the alignment numbers.

I guess we will see what happens when I get my grade 8 bolt kit in, but with a little luck the loose bolts were the majority of the problem.
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Old 10-22-2018, 05:55 PM   #12
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OK, what you are describing sounds like it is not DW, but steering shimmy. I've had that! Mine was bad enough that I thought it was DW at first.


When you installed the TF 2.5" spring lift, did you do anything about the caster? Mine was, in tolerance, but at the low end.



Initially I installed some Synergy adjustable lower control arms in the front & that fixed it, but I found the ride felt significantly harsher. So I swapped them out for a set of AEV caster correction brackets. (Only ones on the market at the time.) Much smoother ride, and never had a shimmy or wobble since the initial change.
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Old 10-22-2018, 06:46 PM
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I have done nothing to correct caster yet. I'll look into the AEV brackets, I like the idea of correction brackets better than those offset ball joints or the expensive adjustable control arms.



I agree that it's a shimmy, but again it triggers a death wobble. I get worried when the shimmy comes on because that's when the wobble happens, it's like a crap shoot every time I hit a bump unevenly. Sometimes it's a little wiggle, sometimes I have to pull over to get it to stop. Everytime I fix something the chances of it turning into a wobble gets less and less. I'll check out those AEV brackets.
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Old 10-23-2018, 06:14 PM   #14
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I know what you mean, but DW means your axle is oscillating sideways. What you are getting is just in the steering, by the sound of it. Mind you, that shimmy can feel almost as bad as full on DW. When it hit me on a corner, I thought I was about to go offroad, over the cliff!


Having said that, if it goes on long enough, the stress can cause premature wear & break some of the parts that will allow DW, like ball joints, wheel bearings, tie rod & trackbar ends...
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Old 10-23-2018, 07:50 PM
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Hmmm, interesting. Wouldn't steering shimmy stop on it's own? Or does it persist until you pull over to stop?

I think you've talked me into trying either JKS or AEV brackets first to see if that settles things down.
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Old 10-24-2018, 12:14 AM   #16
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I had to slow down significantly, but not as much as seemed to be the norm reported by people with DW. They reported it stopping only when they got down to ~10mph, where the shimmy I had would stop by the time I got down ~40mph. It would usually trigger at 50+ after hitting an offset bump in the road.
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Old 10-24-2018, 08:38 PM
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That gives me hope. I just ordered the AEV brackets. I'll report back once I have a chance to get them installed.
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Old 10-24-2018, 11:02 PM   #18
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From what you were saying, I believe they will sort out the issue. Hopefully you will have only good news soon!


As an aside, I found the ride to be smoother once they were in, (I used the least change holes as my lift was only 2"), as they locate the arms to be horizontal, so you get less vertical jarring being transferred into the body when you hit bumps. This was particularly good, since I stuffed 2 discs in my lower back, ~23 years ago.

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