Matching Frequency to Component RPM

At this point in the diagnosis, the vibration has gone through the following analysis:
- The vibration has been duplicated.
- The vibration has been designated as abnormal.
- The vibration has been related either to engine speed or to vehicle speed.
- The vibration has been assigned a frequency from the EVA or identified based on its feel or its sound.
Automotive vibrations are usually related to the rotating speed of a component. Calculate the speed of these components using either an engine speed method or a vehicle speed method. Use the engine RPM readings taken during the road test in order to diagnose the vibrations that are sensitive to engine speed.
If the vibration is sensitive to vehicle speed, determine the rotational speed of the tires. As long as you operate the vehicle at a constant speed, the tires will operate at a constant speed. This speed is measured in rotations, or cycles per second. The reading is then compared to the frequency of the vibration, which is also measured in cycles per second.