28-05-2018, 10:05 AM
The pistons and little end exert several hundred times weight. The up pistons exert far greater accel/decel force than the down. The reasonably exact figures are a simple calculation. With throttle the firing load counters the difference to some degree. At light throttle the bend on crank is considerabel (although because pulses are not sharp as from firing, engine not unduly harsh). So it is not just the rev for the gear change but slowing at high rpm with closed throttle in the gears which is destructive. (If you can counter the wind, it is prudent to coast down 60 mph gradients.) I cant see how the double declutch blip would be worse than following overrun revs, except that it likely to higher rpm.
(When the crank went on my car the final damaging let go was on the overrun)
(When the crank went on my car the final damaging let go was on the overrun)