front end wobble at 40 mph

First, a big welcome to JF! :thumbsup:

And though this is not related to your shimmy, I would remove the dropped Pitman arm and replace it with the OE factory Pitman arm. A dropped Pitman arm should not have been installed with your particular lift and it has caused bump steer. That is where your steering is forced left/right as the front-end moves up and down over bumps/dips in the road.

Next thing I would do is tighten the lower trackbar mounting bolt to 45 ft-lbs. A loose trackbar is a common cause of Death Wobble.

Next, few tire balancing episodes result in perfectly balanced tires. Most tire jockeys only balance tires until they feel they are "good enough" which in the TJ's case, is hardly ever good enough where Death Wobble is concerned. Imperfectly balanced tires are a common trigger for Death Wobble.... that's what triggered mine many years ago.

Next I would set the toe-in to between 1/16" to 1/8" max. Improper toe-in can encourage Death Wobble. You can do this adjustment at home very easily and accurately, as accurately as an alignment shop can do. Use a tape measure like in the below photos (courtesy of mrblaine) to set the toe in by rotating the tie-rod so the fronts of your tires are 1/16" to 1/8" closer together than they are in the back. If your tires are 33", measure at points 33" apart, etc. That tubing is just common 1" square steel or aluminum tubing.

Finally... if you do the above and you still get Death Wobble (or even before), do this... while you have a friend turn the steering wheel back & forth at various speeds, you sit in front of the Jeep and watch the various front-end components. Watch for anything moving that shouldn't be... bad bushing, loose bolt, loose control arm, loose ball joint, loose trackbar, etc.

Good luck.

Yea it's a tire balance issue, and before anyone says "but I didn't change anything with the tires". It seems to me the TJ is very fickle about tire balance, and changing suspension geometry. I have had this happen twice for no reason, once when I put 1.5" coil spring spacers in the front of my TJ (didn't rotate tires then) I got a shimmy in the front end 40-50mph, and again when I rotated my tires recently.

It seems an unbalanced tire on the rear of the Jeep is more forgiving then one on the front.

When the shimmy is between 40-50mph I would bet 100% of the time on it being tire balance issues as long as it goes away between those mph (the frequency and mph will vary depending on the tire size).

Death Wobble is a resonance that oscillates in the front suspension from the steering and suspension geometry being off, and once it starts will not go away until the Jeep is at rest (completely stopped).

Make sure everything is tight, and have your tires balanced.

Thanks guys. I do have a question about the drop pitman arm removal. Why do most companies provide them if you don't need it? Before I lifted the jeep I traded my factory rims and tires for some 32x10.50x15 mastercraft mt mounted on 15x8 steel wheels. Drove great even on the interstate. The tire shop said i had some cupping on the tires and rotated and balanced them after the lift. They also mentioned that my camber on the passenger side was in the green but i would need an adjustable ball joint to make the driver side perfect. My driver side is at a -1 I think.
Another somewhat related question. I'm waiting on my new rims (15x10) will I need to make all new adjustments when I put the new tires that will be bigger (33x13.50) All thelocal shops in my Podunk town look at me like I have a major mystery problem. Thanks again

Thanks I will put the oe on this weekend and try it out. It would be great if that's most of the problem. Again thanks.

I assume from the picture that there is another piece of square tubing on the other side and the distance between is what you're measuring? Forgive me for such a dumb question.

Jerry is smart! Tighten your trackbar

problem solved

Thanks for everyones input. After one by one replacing parts 17 dollars fixed my problem. I had the front wheels balanced for the third time. Now it rides as smooth as a lifted jeep tj.