Relationship of Vibration Frequency to Order of Vibration
After carrying out the road test, the vibration was determined to be either vehicle-speed related or engine-speed related. That determination will identify the vibration frequency calculations that should be done.
VIBRATION FREQUENCY REFERENCE
| Vibration Type | Calculate |
|---|---|
| Vehicle-speed related | Tire-speed vibration frequency Driveshaft-speed vibration frequency |
| Engine-speed related | Engine vibration frequency Engine accessory vibration frequency Engine firing vibration frequency |
In calculating and using frequency readings, it is important to remember the direct relationship between Hz and rpm. One Hz is equal to 60 rpm. This is easy to remember; think of Hz as cycles per second. There are 60 seconds in a minute, therefore multiply Hz reading by 60 to get rpm. Conversely, divide rpm by 60 to get Hz.
Use the Frequency and RPM Calculations Worksheet to calculate system/component frequencies. The worksheet provides the necessary steps to determine each system/component group frequency.