I have had a persistent vibration commencing at 66 MPH and continuing from
there thru 80MPH. I don't (won't) run faster than that. The Yukon has
120000 miles and had the transmission replaced with a GM Certified rebuilt
at about 98000 and then replaced with another Certified transmission after
only 8000 miles under the warranty. I just put a new set of Michelins on it
and complained to my tire guy about the vibration. He clocked the tires and
then after the vibration was still there he replaced two of the four new
Michelins. Vibration is still there and we are all puzzled. The universal
joints seem tight with no play and none of the usual symptoms of a bad U
Joint. I'm now suspecting that in the process of replacing the
transmission(s) that the drive shaft got bent or is out of phase or somehow
got a balance weight knocked off. I do get a slight double clunk when
shifting from reverse to drive and back to reverse, but no noticable clunk
when going from park to drive.
The truck is as smooth as silk until it reaches the "magic" 66 MPH.
Any suggestions or hints on where to look would be greatly appreciated. I
no longer feel I can trust GM dealers. We live in North Carolina.
Thanking you all for your insight in advance.