97 Jeep Grand Cherokee drivetrain noise and vibration.

I seems as though this subject has been beat to death, but in all of my searching I can't find any problem that exactly describes mine. I have
a 1997 Jeep Grand Cherokee Laredo. It has a 249 transfer case-quadratrac, 4.0L engine, and no modifications. I am experiencing a vibration/rub under light load over 30 mph, it goes away if I "punch" it, or release the accelerator. As I go down the road I seems to be coming from directly under my feet on the drivers side. The noise can be described as rub-rub-rub-rub in a monotonous rhythm.
I went underneath and checked the u-joints and shafts, along with the transfer case. The only play I found was in the front output from the transfer case. The shaft can move radially slightly and a little more axially. I am not sure if this is normal, because the rear shaft is nice and tight. I unfortunately did not have a chance to do this in neutral, so my attempts may have been wasted. The u joints seemed to be good, but it was hard to tell at the double-joint going to the front axle. I am inclined to rule out a T-Case bearing only because the noise/vibration happens under certain conditions. I am stumped right now and any help would be appreciated.
Adam
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I think you found it in your universal joints, look again for the telltale rust stained cap seals. God Bless America, Bill O|||||||O mailto: snipped-for-privacy@aol.com http://www.billhughes.com /
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On 27 Oct 2005 05:36:40 -0700, snipped-for-privacy@yahoo.com wrote:

If that is a similar double-cardan joint to the one on my '77 Cherokee, there is a spring-loaded, ball-like "center yoke" between the two crosses (inside the H-yoke) that can be bad and cause vibration. If so, and I believe it is the same, it works off the rear (I think) "cross", and maintains the joint at a constant velocity at all operating angles.
Dan

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Hello Everyone,
I was wondering if you ever found out exactly what was making the noise.I have a 97 JGC Limited. I've had this rubbing/grinding/knocking type noise for a while now, but can't seem to find it. I thought it was the ball joints so I redid the front end, Guess what still made the noise. It seems to happen brakes are applied and the load of the car is shiffted to the front, or going up hill, but still only happenes at random times. PPPLLLEEEAAASSSEEE HELP.
Anthony
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This is a follow-up to my original post about my 97 JGC. I had the problem mentioned above in the first post and this is what I did. I couldn't find any play in the u-joints from underneath the car, so I decided I would take them inside. I removed the rear driveshaft and discovered a bad u-joint, but I think this was just a bonus, because when I replaced it the noise changed pitch a little, but didn't lessen. Then I removed the front shaft and took it for a drive. I don't know if that is a good idea, but everything was sealed up, so I went for a few miles. During the drive the noise was completely gone. I checked the the diff fluid in the front and back and the T case, all was fine. I eventually had the front shaft rebuilt (CV joint and double cardan) and balanced for about $140 at Driveshaft Specialists. This removed just about all of the problem. There is still a very slight noise at the same conditions, but a lower speed range (~50 mph), which makes it bearable.
Adam
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