Quote:
Originally Posted by kyrix1st
Quote:
Originally Posted by Mingwan
Why are people so hung up about the fact that the new M5 will not have a DCT? The 8 speed seems pretty damn quick to me. Dare I say, quicker than the DCT in the now older M5.
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Quickness is one thing, but sense of connection is another. I'm afraid the new torque converters are not as rev happy as the DCT counterpart shown due to its mechanical max rpm limitation and much heavier rotating mass. I'd like to refrain from commenting on how it drives but based on my experience on the same tranny as F90 M5, shifts will most likely feel very numb especially on downshifts. |
As regards inertia (which is what I guess you are referring to) in the clutch/flywheel assembly compared to the inertia in a flexplate/torque converter you have to take into account the complete assemblies in both configurations.
A DCT car has a flywheel (double mass for the S63 engine) and the twin clutch assembly. Which added together weighs roughly (weight of flywheel from Realoem.com):
- Flywheel: 8,1kg
- DCT clutch: 13kg (weight of total clutch assembly, source ZF)
- Total weight of rotating assembly: 21,1kg
An automatic transmission car with torque converter has the flexplate and torque converter assembly. Which added together weighs roughly (weight of flexplate from Realoem.com):
- Flexplate: 2,01kg
- Torque Converter: 17,4kg (complete assembly, source ZF)
- Total weight of rotating assembly: 19,41kg
So, not a whole lot of difference in rotating mass and inertia between the two different systems. Yes, transmission fluid inside the converter also adds to the inertia of that system, I'll agree to that. But the systems aren't night and day apart in inertia. Factor in all the other rotating masses and the percentage in weight difference becomes pretty small.
However it's clear from the rev counter videos that the redline/shiftpoints have been lowered compared to the F10 M5. And that is certainly most likely due to the rpm limitations of the ZF8.