On rides we build the chassis and suspension from scratch it can run into serious dollars so they have to handle/drive good and be vibration free. The suspension and steering geometry is drilled into our heads pretty deep so usually not a problem. For tracking down hard to find vibration issues we use a variable speed strobe light and an infrared heat gun. With the vehicle on the drive on rack and stands we set the strobe to "stop action" speed so any moving component seems to be standing still (think timing light). The strobe is then barely slowed down till the the spinning part seems to be just creeping in movement. When viewed at this speed one can spot any wobble or run out. Vibration creates heat so running in the vibration range will form a hot spot that the heat gun will pick up. With all the fancy equipment I still had a mid sixties Lincoln that drove me crazy; turned out the lads at Ford had too great a distance between pulleys/idlers for the a/c compressor belt(s) which would go into harmonics that one could feel in a 5000# tank so who knows?

Evan