Help me identify noise from front-Please

[gshep]

This is not the traditional noise front end noise. When I let up on the accelerator after traveling at speeds over 50 MPH, there begins a very loud banging noise from the front of my 99 GC 4.0. that continues until I put my foot back on the accelerator. It seems more from the right front but it is hard to tell. Even light pressure back on the accelerator causes it to stop but I can't just keep going faster and faster.
I had one mechanic put it up on a rack and he could find nothing loose or broken. He thought it may be a transfer case problem, but just maybe. I took it by the dealership and the shop foreman drove it and stated he had never heard this noise before. They would have to just start checking it out.
I do not have the traditional grinding noise when turning. Any info will help. Do you know something that will help me narrow it down? I can't afford to just start randomly tearing down transfer cases, drivelines and whatever else.
Thank you for your help.

[eortega56]

Hi, I have a 99 Grand Cherokee too. I had a problem like you describe and I was the both ball bearing of the front axle. ask a front suspension and steering specialist that test ur jeep. If The noise is more heavy at high speed ,
is like a huge humming noise comming from front but you cant realize where it from,you feel like the jeep is responding more slowly like over wheigted and you inspect that the bars ball joints and all was ok may is the ball bearing box. They are located at the front axle near the axle yoke. Tell that to the specialist or to the dealerTo get them cheked.

Other thing that can be are the main supports

Check the motor and transmission supports to car chassis may be one of them is broken.

[fordin K]

ok mentin this to the dealer.... maybe you need an updated track bar and both upper control arms NO: 02-11-99 Rev A

[gshep]

I have discovered that with the jeep parked, I can grab the front drive shaft and move it colckwise/counter clockwise enough by hand to make a good noise in the front differential. Should I be able to move it this much?