Death wobble at 40-45 mph the steering will shake violantly, I have the tires balanced and a new stabilizer put on and the front end allinged and the track bar seems tight. I have a Rubicon with 265-75-16 tirs and there is a winch on front.I bought this used about 3 weeks ago.

My Death Wobble started immediately after I installed a set of Coil Spring Spacers (to lift 1.75 inches) on my stock 2005 Jeep Wrangler X. Turned out, the DW was because while changing the height, I also lowered the CASTER angle in the front end. So, to fix it, I could have purchased a set of eccentric bolts for $50+. Instead I went out and purchased a piece of 1.5 inch flat bar for $10 from OSH. I cut out 4 1.5 inch squares. Then i drilled 7/16 inch holes centerline, but close to one side (in exactly the same place) on all for squares. I then removed the lower control arm bolts, nuts and washers. I installed these square offset washers I made so the front axle would be pushed forward (to increase the Caster angle). The toe setting changed a bit, so I reset them to about 1/8 inch toe in. After driving my Jeep, I noticed there is no more DW. The steering wheel was off center, but after 3 attempts, I have that perfectly centered. I have every intension of having the alignment checked, but not till after I find the new tires I want. If anyone is interested, I can draw out and photograph the cure and send it to you. My e-mail is bb62471(at)yahoo(dot)com.

The "death wobble" is caused by any number of worn parts, but USUALLY it's worn tie rod ends. This is very common on new jeeps with the Y style tie rods and very old jeeps with the multiple tie rods/bell crank combination. The steering stabilizer helps control all the extra movement, so when it wears out, you feel the wobble.
Either check all the components yourself or take the jeep to an alignment shop and have them check for loose/worn parts, then replace them.
Keep tires balanced. DON'T try to steer out of it, you can't react as fast as the wobble. It's called "death wobble" because people try to steer out of it which compounds the problem, causing loss of control.
Tap the brakes to slow down and keep the steering wheel centered. As your speed drops, steer to the side of the road, collect yourself, and continue to the repair shop.

It is most often the stabilizer shock... Cost is about one hundred and twenty dollars to have it fixed... I have had to have it done to both of my jeeps... 2002 and 2006

I had this same problem at 54-57 mph. I rotated tires, no help. I put on new tires, no help. I replaced track bar and stabilizer, no help. I bought a set of rims and tires off my buddy's 2000 Jeep and wobble went away. I think this is a rim problem, for some reason they would balance but never fixed the problem, until I replaced the rims!