What limits shift time is the fact that reducing the time increases the accelerations required to synchronize the inertias either side of the meshing gears, therefore the 'stab' torque increases. The clutch preload springs effectively cap this torque. Of course another limit is the actuator response time.Tommy Cookers wrote: ↑Wed May 30, 2018 9:30 amand otoh ....
how can taking no action to modulate PU behaviour give a quicker shift ? (than taking action designed to help shift)
also now the gearbox is required to have a long life
rpm change within 1 rev (eg by cutting) is a significant proportion of the nominally required 15% rpm swing for shifts
During an upshift for example, part of the rotational energy stored in the engine cranktrain assembly is passed on to the driveline once the gears engage and manifests as a short burst of wheel torque. Slowing down the engine during the upshift (spark/ fuelling/ K ,etc) significantly decreases the rotational energy (as it is proportional to the square of angular velocity) so the initial wheel torque spike decreases which is not great for performance.