Hey Everyone!
Just put a RC Series II 3.5 lift on my JK, with a set of used 37" KM2s, and pro comp 7069 rims (17"). The rims are lug centric, fyi. I got everything put together (Changing Pitman arm was a major PIA) and am pretty happy with the kit. Everything feels fine up till 40, and on my first highway run I got a serious wobble right at 50 mph. It wasn't a death wobble (if it was, no reason for the word death) but it was a serious wobble. It would transfer through the steering wheel, moving it roughly a 1/16 turn in each direction at a moderate speed. The road was an interstate, in fairly decent shape (I have travelled before lift no issues).

I went back and found a not torqued upper track bar bolt, and torquing this to ~130 fixed a lot of the wobble, but it is still present. The jeep doesnt feel out of control, and it dissappears about 60mph. Does anyone have direct experience or a sense of direction to attack this? My research is leaning towards tire balance, which I had done when they were mounted and balanced (Friday).

I'm planning on swapping the rears to the front, and seeing if this changes the wobble (would verify tire issue, correct?) and if nothing else, throw the stock0 tires back on and isolate which is the cause, the lift or the tires.

Lift included springs, shocks, fixed LCA, drop Pitman ( i will be swapping for drag link flip eventually), Fr and Rr trackbar brackets, and other misc (bump stops, etc.).

Thanks

 

Just because they were balanced, doesn't mean it was done right. Rotate and have them rebalanced. (on two occasions, I have had discount tire mess up the balance and had to go back the next day...)

After that, go up to the Writeups area. Stuck right to the top is Planmans DW/Shimmy Diagnosis. Wouldn't hurt to follow through the entire thing to check all of the frontend components. Maybe another component isn't torqued or is wearing out.

Haven't heard of a drop pitman causing a wobble, but there have been lots of posts of other problems with them. Your plan to swap to a flip is probably a good call.

 

I had a speed sensitive wobble since 5k miles. I replaced the following: drag link, tie rod, ball joints, replaced wheels, new tires. Replaced lower control arms with fixed arms to correct caster of 2.5" lift. Tried new track bar, but it rubbed on diff. Grade 8 hardware all around. Had original 35s balanced, then roadforced. Roadforced again with new tires on old wheels.

I just finally fixed my wobble. I literally cried in the driver's seat. True story. Not a sob type cry, but I definitely teared up from happiness. I'm man enough to say it. Diagnosing a wobble is literally that frustrating, so I feel for you.

The culprit was the pro-comp steel wheels from 4WD parts. I even drove to their store and they replaced 2 of the 4 wheels because they were bad from the factory. Turns out their wheels just suck and they will never balance well. With my new tires (duratracs) on the old wheels, they wobbled. New, aluminum wheels, wobble gone.

The wobble in the wheels transferred all the way to the steering wheel, just like you said. With enough time, it wore out my ball joints and caused full blown DW. When I replaced the ball joints, I just went back to regular wobble. I wish you the best of luck, I really do. If you mis-diagnose the wobble I guarantee it won't be the end of it. But speed-sensitive wobble is almost always the wheels or tires. 99.9999999% of the time.

Good luck.

Also Planman is the bomb. His write-up should go in the damn manual if I had a say.

Edit-- I checked your wheels, and they are aluminum alloy. Perhaps that isn't the culprit like it was on mine. I'd bet 100 internet bucks its your used 37s. That's a lot of tire to balance...

 

I may need to part ways with my pro comp steel wheels.

 

What is often times unintentionally over looked, is that steel wheels constantly change shape ! Though not as extreme as water thawing and freezing, the same principle of expansion and contraction of properties with limited tolerances, their shape can ever so slightly change. Again, not a perfect example, but you wouldn't run straight water in a radiator given the choice because of its limitations to extreme hot and cold environments. Aluminum wheels are more expensive for many reasons; their pros out way any cons, (price aside), and those tolerances are more forgiving. Secondly, is the ever seeking goal for weight reduction when choosing tires and rims. Point is, as stated by others respondents, the balancing of tires and their wheels, can be tricky, and some wheels may never balance because of manufacture or material imperfections. (Yes I am generalizing and there are exceptions to each case). Rotating tires is an easy way to pin point or delete from your check list. Especially if you have a matching fifth wheel/spare. Best of luck.

 

One thing i noticed this morning on my commute is that after a while, the wiggle changes speed it occurs at. To me this is still pointing at tires. Ill rotate this evening and update!

 

When you put your wheel on did you remove the steel brake rotor retaining clips? They are on the hubs from the factory and the factory wheels have provisions for them. Aftermarket wheels dont. The clips are small steel rings that are slid over the wheel studs from the factory. One per wheel for a total of four per vehicle. Make sure you rip them off before mounting aftermarket wheels.

 

I did not remove them, i thought they were only removed for wheel spacers. I will try this before rotating.

 

You definitely want to remove those. Your wheels aren't flush on the hubs right now. Bet that will solve your issue.

 

We had a "wobble" at about that speed on 37" KM2's too.
When I read the thread title, I thought to myself, " I wonder if he is on KM2'S?"

Good luck