Lift induced vibration

Okay, where to begin.....

When I installed the superlift 4" lift I acquired a vibration. The vibration starts at 15 mph and will last till 25 mph and then everything is fine. It happens when accelerating, coasting, breaking, turning etc all in that speed zone. It is most extreme at 15 mph. I feel the vibration in the floor boards, steering wheel, as well as everything in the cab will vibrate. The sound alone makes it noticeable because of how loud it is. I have had a couple of mechanics at different garages test drive the vehicle, and I have gotten different answers. One said it was my tires causing it. Another said it was bearing noise and someone else said it was my wheels that were causing it.

I've been trying to diagnose and fix the problem myself, but recently it has been getting to expensive. This problem has been going on for about 2 years. In this 2 year time frame I had both my front wheelspeed sensors go bad at different times. since I was in there, I decided to replace the whole hub, since it comes with the sensors. No change was noticed. I had my front differential isolators go bad, so I changed all 3. Again no change. I removed my front drive shaft and found the u joints were bad. I figured that surely would cause it. I replaced my front drive shaft, and that didn't fix it. I put my stock wheels on, again no chage in sound as well as the feeling when driving. The noise sounds like it is getting worse.

Recently I had a couple of buddies ride in the jeep. With out me saying anything, as soon as I hit 15 mph the looked at me and said what the hell is that.

Im not really sure on what to do next. I've checked the engine mounts and they seem fine. I'm not sue if I had a problem with my rear drive shaft if that would cause a problem or not. Do I have a problem inside the front diff?

Recently I put rcv cv axles in. I am having a problem with them. So right now the jeep is out of service until I put my stock axles back in. I have to send my rcv axles back. I will post pictures and what the problem was in the thread I started for the axle installation.

So if anyone has any recommendations, please let me know.

Thanks

Vibrations constrained to specific speed ranges are normally a balance issue; resonance.

However, 15-25 is also normally an 'acceleration" zone and vibrations during acceleration are often due to worn components (u-joints, cv axles, etc).

It's possible your stock CV axles were on their way out. When you swap the RCV's out put some new axles back in. Since you already replaced the front driveshaft that'll help rule out the worn components.

Thanks Matt. I appreciate the advice. Since I dont know how long RCV performance would take, I thought about ordering some cheap ones, installing them and see what happens.