From recent experience with our two Volvo's (98 V70XC and 02 S60AWD), I
find that a mild increase in accelerator pressure as the lever selects a
lower gear allows the engine to speed up enough to synchronize the
clutch and gears (again - manual or auto) so that input/output speeds at
the clutch involved are close enough to stop any obvious synchro
problems.
bob noble
Reno, NV, USA
that's one reason I would always prefer a manual , you approach a
corner, double clutch down into 2nd or 3rd, this synchronizes the
motor with the drivetrain. ( take it out of gear, adjust engine speed
to match drivetrain, re enguage then shift.) this puts the energy from
the braking effect into "spinning up" your engine and flywheel,
saving your brakes and not wearing your synchromesh. What you are
doing is making the gears inside the box match speeds. then when you
come out of the corner you can then get a free boost of power as you
shift back up. in other words you can reuse that energy, rather than
waste it.
the smooth roll in and out of gears also makes the car handle better
because the forces you are transferring to the road , braking, gearing
down, acellerating, gearing back up are one smooth motion
it takes practice to drive smoothly, more to doubleclutch smoothly
but it saves gas and your drivetrain. I have bought cars with
transmissions that were stubborn to shift , and worn them back into
operating smoothly, through another 50 k of driving them smoothly.
one can take things a step further in a sporty sense, and combine
this action with rolling off the gas and onto the brake and back on
the gas while doubleclutching down and back up. it takes practice to
get this right and the gas and brake pedals need to be situated right,
but it gives one a great feeling when it comes together into one nice
fluid motion.
In my opinion it is the "twisting action" that wears your drivetrain.
Every time you jolt it by either accellerating or decellerating with
sudden force it makes every part involved from your pistons to the
tires on the road reverse forces with their mating parts from a
"driving" mode to a "driven" mode. this causes a wee bit of wear to
all mating parts, splines, ujoints rear axle gears transmission gears,
clutch. Even all the bearings involved are affected because the load
on them changes direction. lets not forget all the rubber parts , like
your transmission mounts etc. in lower gears you are able to stress
these parts much more than in higher gears, because more torque is
involved.
and of course the greater the force on every part , the more wear.
so my opinion for what it is worth is:
of course, use your transmission to slow you , but the harder you
"jolt" your drivetrain, and the quicker it will wear, so if it goes
down into a lower gear with a great big thud it probably isn't a good
thing. same goes for flooring it in first.
also since it is a proven fact that if one chooses roads which go
downhill, one will save gas. so if you have a choice , go downhill in
mexiican overdrive (neutral)
Phil
