Why would my front end shake at 40 mph than quits at 55mph?

SOURCE: death wobble

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.

SOURCE: steering and front end shake bad when hit brakes

Check your front brake discs (rotors) - they may be warped. Check front brake calipers - are they working? Check condition of tyres. Answer is more likely to be the rotors. Your symptoms are dangerous.

SOURCE: my front end shakes when i hit a bump at 50 mph, the front tires

could be a bent rim ? have you changed the universal joints? how about the tie rods and stabilizer bar

Testimonial: "thank you very much, i will do this first thing. i have had several people look at it , and of course they have told me it was not the tie rods,i knew"

SOURCE: 2001 Jeep wrangler, at 45-50 mph, the front end

Welcome to the jeep "wobble of death", Could be a series of things, Alignment, bent rim, tie rods, balancing of tires etc.

SOURCE: FRONT TIRE BOUNCE AT 40-50 MPH

relace your shocks. the design of any dampner(strut or shock design) is to return the wheel to the road for handling and safety. when the shock is worn out is with continue to bounce like a basketball. it has no more strength to return to wheel to the road. a common misconception is that they are there to absorb, not true. the springs or torsion bars are there to absorb and create ride height. the shock does nothing more then return the wheel to the road. simple and inexpensive.