Calculating Propeller Shaft Revolutions Per Second, or Hz at Concern Speed
WARNING: This page is about a different car, the 2007 Suzuki XL7. However, it is still accessible from the selected car via links, so may be relevant.
- Determine the first order rotational speed of the propeller shaft system in revolutions per second, or Hz, based on the first-order rotational speed of the tire/wheel assemblies and the drive axle, or axles final drive ratio or ratios.
11 Hz X 3.42 drive axle final drive ratio = 37.62 Hz, rounded to 38 Hz, first-order propeller shaft rotation related
- Compare the rotational speed of the propeller shafts at the specific vehicle speed at which the disturbance occurs, to the dominant frequency recorded on the J 38792-A during testing. If the frequencies match, then a first-order disturbance related to the rotation of the propeller shaft is present.
If the frequencies do not match, then the disturbance may be related to the second-order of propeller shaft rotation.
- To compute a second order propeller shaft rotation related disturbance, multiply the first order rotational speed of the propeller shaft at the specific vehicle speed at which the disturbance occurs, by the order number of 2:
38 Hz X 2, for second order = 76 Hz second-order propeller shaft rotation related
If the computation matches the frequency of the disturbance, a disturbance relating to the second-order rotation of the propeller shaft is present.