Experimental Root Cause Diagnosis for Scooter NVH Problem

This paper focuses on the diagnostic methodology and troubleshooting process for the coast down noise annoyance for two types of scooters. Both the subjective noise assessment and objective evaluation of the gearbox near field noise and gearbox case vibration were performed in this work. The objective evaluation adopted time analysis, spectrum analysis, order analysis and binaural analysis to identify the acoustic characteristics of the noise annoyance. In addition, the excellent correlation between gearbox case vibration and abnormal coast down noise was confirmed. The diagnostic results show that the noise annoyance is resulted from the improper assembly clearance tolerance between specific parts for Type A scooter, and from the improper clearance between specific parts for Type B scooter.