This paper shows a whole noise quality checking system for the new developed 6th speed automatic transmission manufactured in USA. Due to demand for manufacturing of the high NVH quality transmissions in the mass product line, some special checking system called EOL NVH is adapted. This EOL system is using vibration sensor and analysis technologies. Through adapting vibration analysis technologies and functions likewise RMS, crest factor, harmonics, peak, band and order tracking, various noise problems caused by wear, nick and deformations could be successfully detected and predicted. Therefore, automatic transmissions manufactured in the USA could get high NVH quality. The developing process described in this paper and results on EOL system will offer good guides to the engineers who built the next transmission factory.

In order to improve the planetary gear noise of the new developed 6th speed automatic transmission, it needs to understand noise mechanism. Basically, many transmission’s components have an effect on the gear noise. In this paper, planetary gear noise sources which are influenced by gear tooth shapes and backlash among the gears, position of pinion gears, and misalignment of the sun gear are studied and experimented. Also, transfer-path likewise one-way clutch contacted between the carrier and case, and valve-body covers are also researched to reduce the transferred vibration and radiated noise levels. After developing the planetary gear noise, its evaluation specification is adapted to EOL (end of line) equipment to check the transmission’s noise quality in the factory.

To improve the gear noise quality, gear tooth grinding machine are widely used in automotive industry. While using the gear profile grinding machine to improve the gear tooth quality of the transmission, several defects such as chattering, tooth waves that cause the gear noise occasionally happened. But it is very difficult to solve that problem, because there is no one who knows the setting up the optimal grinding condition appropriately. The abnormal manufacturing conditions which make the gear noise make the engineer to spend a lot of time, effort, and money. Due to demands for solving the serious abnormal gear noise happened in the automatic transmission in the mass product stage, the vibration checking process in the worm wheel axis, work rotation and fixed axis of the grinding machine were adapted to find the root causes. As a result, gear profile wave are affected by the work rotation axis's unbalance which is caused by worm wheel feeding speed. And