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Synchronizers are the critical element in manual transmission to match the speed of target gear, and allows smooth gear shifting. Generally, synchronizer failures are related to design parameters, like geometrical construction, material, and lubrication. This paper throws light on one different parameter for synchronizer design namely the angular accelerations which are imposed on synchronizer, due to vehicle level systems. The recent developed high-power density engines develop angular accelerations due to smaller flywheels. These angular accelerations are detrimental to the life of synchronizers. Brass synchronizers exhibit structural damage in synchronizer due to the angular acceleration. The carbon liner synchronizers do not withstand the angular acceleration and fail rapidly due to liner wear. The synchronizer rings can move freely in the available space due to rattling. The synchronizers which experience higher angular acceleration fails immediately.

Synchronizers are the most critical parts of a manual transmission. There are classical calculations available for the synchronizer design and studies are available for the normal functioning of synchronizer rings which describes how the synchronizer behaves in the event of gear shifting. The objective of this study is to describe the synchronizer behavior when synchronizers are not functional, i.e., in other gear engaged condition and the rings are free. This study describes the failure mechanism of the unused synchronizer rings which are moving freely in the packaging space. The findings of this synchronizer design cannot be limited only for synchronizer performance and standard durability calculations. To ensure proper function of synchronizer rings and to achieve the required life the external parameters like clearances, lubrication, clutch design for dampening torsional vibration from the engine are to be considered.