i have a 1999 jeep grand cherokee sport with the I-6 engine. i go down the highway n the whole vehicle starts shaking vigorously. IT would shake you awake if you were sleeping. it doesnt happen all the time just on and off. i had the front end chekd and everything is tight n good and the tires are good so its not the belting in the tires. the shocks are new. i dont know what the problem could be. the balljoints n evrything are fine! please help!!

 

It's called death wobble. Go search about it. I bet it's your trac bar. Get a new one.

 

^^x2 Started experiencing it 2 weeks ago and what i found was that the tie rod at the end of my track bar was shot. I replaced it with a HD track bar and it disappeared..well, almost. Now i just have a little vibration but hopefully this weekend it will be taken care off when i replace the axle u-joints and ball joints.

There are a lot of articles about the dreaded "death wobble". ABC news in Cali also did a segment on it. Google it and you will have loads of info

 

The problem with that segment is.. its not just jeeps that have this issue. F-150, Broncos, Chevys, and for ABC to target jeeps like that was BS,
Here is a link that I have given lots of my friends, being I have both wrangler and cherokee the works are pretty much the same, and even with the fords amd chevys friends they found this to be the issue too. Atleast check it out, and look here first before spending $$$$$$$ and still have a shake!

 

Um, you forgot the link.

 

That is true. I've experienced it on my '85 K5, '84 F150, '92 Bronco, '95 Silverado...But not as much as on my XJ. I mean, it felt like my front end was going to come right off from under me at 55mph.