Changing Down Gears.
Initially you may fail to achieve smooth gear changes, the reason may be in your
technique, a common fault, is failure to synchronise engine speed to the newly selected
gear, with the result that a jolt is felt at each change. This is particularly common
when changing to a lower gear as the engine will need to increase in speed to successfully
change gear.
An understanding of causes should help, and the following example will explain the
principles involved. A passenger car travelling at 60km/h in fourth gear may show
a tachometer reading of, say 2,200 rpm. In third gear, but still at the same road
speed the tachometer may show say, 3,000 rpm This means when changing from fourth
to third while still maintaining 60km/h, the engine speed will need to INCREASE
by 800 rpm or 40%.
You must accelerate to the required engine speed as you select the next gear and
HOLD the new engine speed until the clutch is again fully engaged, the engine speed
may be judged by ear or tachometer.
All changes whether to higher or lower gears require anticipation, and you should
be in the correct gear BEFORE the hazard, intersection, corner or steep descent,
as the case may be. By doing so, both hands are free for steering control and it
will be easier to concentrate on the approaching manoeuvre.
The "kick-down" method in the automatic vehicle should be employed where a sudden
or unanticipated surge of power is required.