Which Type of Transmission Offers Better Overall Performance?
2 Answers
MT transmissions perform well overall, but they are not automatic and have poorer shift comfort. Theoretically, the best is the dual MT clutch DCT, which retains the advantages of MT transmissions while shifting like a dry DCT, with no drawbacks, making it the theoretically best DCT transmission. In the past, dry DCTs couldn't handle high torque, and when clutch reliability issues weren't a concern, they could be called the "endpoint of transmissions." Theoretically, dual AMT-style DCTs can handle high torque, and the dual MT clutches used are highly reliable, with overall performance surpassing the "endpoint of transmissions." The dual AMT-style dual-clutch solves the issues of low-speed shift jerkiness, vibration, and noise in DCTs. The reason for jerkiness in DCTs is insufficient clutch slip power and slow clutch engagement speed—neither of which is an issue for MT clutches, so dual AMT shifts can be smooth. DCT vibration occurs because the drivetrain's resonant frequency isn't low enough, which is due to the clutch's secondary mass being insufficient. The combined mass of the two MT clutches in a dual AMT is large, resulting in a sufficiently low drivetrain resonant frequency, preventing vibration during startup and low RPMs. DCT noise is caused by synchronizer gear clash, as wet clutches don't fully disengage, making synchronizer clash more likely. The dry MT clutches in dual AMTs fully disengage, preventing synchronizer noise, and the normally closed MT clutches avoid clutch collision noise. The dual AMT-style dual-clutch has no jerkiness, vibration, or noise and can handle high torque, theoretically making it the "endpoint of transmissions."
Having driven for over twenty years, I believe a truly good transmission should be reliable in all situations. Manual transmissions offer an engaging driving experience, but your left foot gets exhausted in city traffic jams. Automatic transmissions like Aisin's 6AT provide smooth and comfortable performance with decent fuel efficiency, especially during stop-and-go traffic - they're worry-free. CVT transmissions like Nissan's deliver seamless acceleration and excellent fuel economy, though some drivers find them lacking sportiness. Dual-clutch transmissions such as Volkswagen's DSG shift quickly and deliver punchy acceleration, perfect for driving enthusiasts, though maintenance costs are higher. Overall, I think the best transmissions are those that are effortless to drive, reasonably fuel-efficient, rarely break down, and perform well in both city and highway conditions - automatic transmissions strike the best balance.
