I intalled a 2" lift on my 2010 colorado 2wd. When the truck shifts into 2nd gear and at more than 1/4 throttle there is a slight vibration coming from the drivetrain. I have no other vibration at any other time and did not have it before the lift. Thanks -mike
The next possibility would be universal joints. I highly doubt it though. In theory, you changed the angle the rear drive shaft ever so slightly. If the universals have a wear pattern from before, you may experience a vibration as the bearings are loaded differently. Again, highly unlikely.
Did you change tires too? The coincidence I think of could be amplified by a stiffer suspension than it was before and not absorbing any of the vibrations that have always been there but never making it to the driver seat.
Did you change wheels? If so, is the center bore on the new wheel bigger than the center bore of the stock wheel?
I have a vibration issue and my lug nuts are backing off over a 3000 mile period. Best we can tell, the wheel has movement, slippage, enough to create a vibration and loosen nuts because the center bore on my wheels is 108mm and the hub center is 100mm. I have ordered hub centric rings as a fix.