First off, its not death wobble, I do no believe its the rotors (i have had warped rotors before and can tell the difference), and its been getting progressively worse for the last week or so. When breaking it feels/sounds the worst, but is becoming noticable while cruising and decelerating around 40-50 mph or so. It feels as if it is coming from the floorboard in the front. Not sure if it is drive-line vibes, or if it is a bad u-joint, or something of the sort. Maybe motor mounts???

The sound is not a low thumping, or causing the Jeep to shake. It is more of a grinding type noise, almost like spinning a quarter on a table (if that makes sense lol). Any suggestions would greatly be appreciated. I have the day off work tomorrow and I would very much like to spend the day diagnosing the problem, and possibly fixing if time permits (probably not though). Thanks ahead of time for the help.

 

For mounts you could power-brake it in both drive and reverse and watch the engine and see if she's jumping around in there. (I can just look down and see my drivers side is long gone). A bad trany mount will "radio" vibration into the floor pretty well. You might pry on things under there with a bar and see how it moves. Of course U-joints go out pretty often.

The rotors shouldn't do anything unless you are on the brake. I'd rule out the U-joints first myself.

 

I checked all the u-joints (drive shaftes and all 4 axles), tie rod, sway bar, calipers, rotors, motor mounts, tranny mount, and t-case. Everything seems to be in pretty good shape. A buddy of mine took a ride in my jeep today to see if he had an idea of what was wrong. He is not a jeep guy, but definitely knows a thing or two about cars in general. He said that it sounds as though my cv joint is going out. Do I even have a CV joint??? I didn't think I had one. The jeep wouldnt make any noise/vibration while driving at first, but after about 5-10 minutes of driving, the vibrations returned. This leads me to believe it is possible its the cv joint ( if I have one that is... I thought I just had u-joints) , mainly because the boot could be destroyed and the grease is gone, allowing the cv to make noise once it gets hot. What do you all think?

 

It is very possible that could be the problem. Did you by any chance check you wheel bearings?

 

I did not check the wheel bearings. I am not a mechanic by any means, and I am unsure how to check the wheel bearings. I will do some research online to find out how to check the bearings. I just climbed underneath my jeep to see if I even have cv joints. I do not (as I expected). There are u-joints at all 4 axles, and u-joints at the front diff to drive shaft, at the front drive shaft to t-case, at the t-case to rear drive shaft, and at rear drive shaft to rear diff. I will check the wheel bearings (if I can figure out how by looking on google). What else could it be??? Thanks for the help.

 

I have a front U-jont that has been pretty bad for years, snaps and clatters in 4WD turned hard. I don't notice anything in 2DW at all.

The pipe touching the floor or a bad trany mount are two good ways to make noise/viberation.

The rear u-jounts see allot of use. You can jack up one rear a little, then feel and watch them while the wheel is turned forward and back. Any play at all between the ears on the joint and it's done.

A wheel bearing will often change sound cornering. Also if you jack up the wheel and can feel play top to bottom in it you can suspect the wheel bearing.
Sometimes one going bad will start getting hot before is gets loose and starts making noise.

Stuff on joints > http://en.wikipedia.org/wiki/CV_joint