4 Wheel Drive/SUVs: 98 Jeep GC: Vibration at certain speed, jeep grand cherokee laredo, jeep grand cherokee

Question
Hi, I own a 98 Jeep Grand Cherokee Laredo (6 cyl.) with 68500 miles on the odometer. In the speed range between approx. 62 to 67 Mph (2000 to 2100 rpm), a significant vibration of the whole car and the interior is noticeable. In addition to that, the noise level raises instantly.
When driving faster than 67 Mph the vibration and the noise become “normal” again. This is also the case when driving slower than 62 Mph. The problem seems to be speed-dependent (and limited to a certain range), as in a lower gear with an rpm of 2000 or 2100, there's nothing extraordinary noticeable.
P.S. I got the tires balanced and rotated, but nothing changed. Any ideas?
Thanks.


Answer
Christopher,

I would still suspect a tire problem.  See if you can find a shop that does wheel balancing with the tire still mounted to the Jeep.  Many tire shops, or alignment shops can do this.  It wouldn't hurt to have the front end aligned, and have all the bearings checked.  Other than that, you may have some bad universal joints, or a driveline that has become unbalanced.  For this, you may need to go to a driveline shop.  If none of these appear to be the problem, check your motor or transmission mounts.  I have seen this problem with some automatics transmissions when they start to go bad..

  Carl