"Dave Plowman (News)" wrote in message
...
In article ,
NY wrote:
It must be good to feel smooth, fairly constant acceleration, without
pauses in acceleration while the transmission (auto or manual) changes
gear.

No reason to have a pause in acceleration while an auto changes gear.

All the automatics I've driven have given a noticeable lurch (due to
momentary disruption of power to wheels) when they change gear under hard
acceleration, even if the change is undetectable under gentle acceleration.

There is also the problem that the rate of acceleration decreases with each
upward change of gear (lower mechanical advantage of higher gear lead to
lower torque at wheels). In a manual car you adjust for this: as you change
up you apply slightly more accelerator pressure than you would in the lower
gear, even allowing for the accelerator not needing to be pressed as far
because the engine speed is lower - when you are learning to drive you learn
to make the adjustment sub-consciously. But in an automatic further pressure
on the accelerator to maintain the same acceleration can occasionally cause
the gearbox to shift back down to the gear it used to be in: I always have
this problem as I accelerate out of a roundabout and end up "see-sawing"
between high acceleration in lower gear or less acceleration in next gear
up. I end up thinking "you've changed up into third, now *stay* in third and
let me accelerate in that gear".