Need Help with Diagnosing
 

I have a 2013 JKR. It has a MetalCloak 3.5" lift, full Metal Cloak suspension parts, Teraflex HD Track Bar, 35" tires, etc. Has 44,000 miles.
Everything had been perfect with this Jeep.
About 4,000 miles ago, I began to notice a steering wheel shimmy. The shimmy will happen from about 35-40mph to about 65mph. I know it sounds like balancing but it is not.
Sometimes it's really bad, other times it's perfectly fine, like there is nothing wrong. When it does shimmy I can feel it through the stick as well. Here is what has been done to try and see what is wrong:

1A) Did the move steering wheel back and forth, while another person looked for play in the trackbar. It's solid as could be.
1B) Checked the ball joints and noticed that the bottoms were toast, and replaced upper and lowers. Shimmy was still present.
2) I swapped tires/wheels with another set I had, that I know run perfect on my other rig, to see if that was the cause. They did not make a difference.
3) I then moved onto looking at bearing/hub assembly on both sides. They seemed good, but replaced anyway. Still there.
4) I also had a MetalCloak drag link flip kit since X-Mas, and I did that install. Makes the JK drive really nice now, except for the shimmy.
5) Checked alignment and caster settings which are right on.

I can not figure out for the life of me, what is wrong with this JK. I would love to hear any other thoughts of what could be checked to see why it shimmys......any help would be great!

Have you checked your driveshafts? Is the front an aftermarket? I’d think about getting your driveshafts balanced.

Since it seems that you have looked at all of the mechanical stuff, let's touch base on this a bit more.
Do you have the alignment specs handy? Was anything adjusted to bring it into spec immediately prior to the shimmy?

Did you rotate the tires? Or just swap to an old set that may be worn down in the same pattern as these? Were they balanced more than once? Preferably by different people/different machines? (using Discount Tires free lifetime balance/rotations, I have gone in with no vibes, and left with a bad shimmy. Other times, I have gone in with a shimmy and it has taken two or three tries for them to get rid of the vibes. Just depended on who was on the machine that day.) So, not saying it is a tire issue, just that you aren't finding anything else so it's worth discussing.

I installed brand new front and rear driveshafts.....the stock were going bad and it needed to be taken care of anyways......didn't change the shimmy at all.

I don't have the alignment specs handy, but everything was in spec. It was done some time ago.
I did rotate tires that are on it now. The other set I have run perfect down the road on my other jeep. They are a different tire all together and fairly new.
I still have a shimmy with the different tires/wheels.

I'm thinking of attaching my GoPro to the underside of the JK and driving down the road...see if I can catch something out of whack........just really don't know what it is causing the problem.

I had this exact thing happen and as odd as it may sound, it seemed to be caused by uneven tire pressure. I noticed a couple of my tires seemed to be sitting kind of low. I was driving to work on the highway and as soon as I hit 45MPH, it started shaking like all hell was breaking loose. Then the moment I reached over 60MPH it stopped, then as soon as I slowed back down, it started shaking again. Not knowing what was going on, and knowing a couple of my tires were low on air, I stopped off at a shop and made sure they were all filled to 35psi and much to my surprise, it never happened again after that.

I doubt that's your problem since you swapped tires, but may be worth checking just in case.

Spot on
 

I agree that this is the next thing to look at. An off balance front drive shaft can cause a side to side shift in the steering wheel and all the way down the drive line.

It's weird that
 

It's weird that you would feel the shimmy in both the steering wheel and the shifter unless it was suspension related. Specifically a shimmy and not a vibration which could come from a loose mount trans/engine. I would look at the track bar again, upper and lower mounts, sprung and unsprung, I'd also look for a witness mark around the bolts front and back. Weird question, do you feel the shimmy in your butt too or just your hands?

both driveshafts have been replaced......they are balanced and have been checked.

It's just in the hands and shifter to an extent. Definitely up front, not felt in the seat or floor........
My next move is to replace the track bar with Metalcloak one......then everything up front has been replaced (even though the current trackbar is a Teraflex HD one). If I can get a good day I'll take a camera and get some video to see if there is anything to see.