Absolutely, every shift (particularly down) of every transmission (synchro
or not) should be double clutched, if not entirely floated. It's dangerous
and wear-inducing to rely on synchros and to rely on the rear axle to bring
the engine revs up to match the new gear ratio.
> back when i started driving i was taught by my dad to double the clutch
> to
> save on clutch wear but i never really got into the habit and nobody
> else
> seemed to be doing it.although in some of the really old driving manuals
> its taught.if i can remember you re-ingage the clutch while you're
> inbetween
> gearshifting instead of keeping the pedal down.is it worth getting in
> the habit?
It most definitely is worth it. You can depress the clutch to get it out
of gear but depending upon the engine/trans combo and your finesse you can
usually just slide it out of gear if you coincide light pressure on the
stick with lifting off the throttle. To downshift, you have to blip the
throttle slightly, while in neutral, to match engine speed (input shaft)
with output shaft speed. That's the whole point of double clutching, to
match the speeds so the gears mesh together rather than being forced. It
also keeps the rear wheels from locking up when you unclutch, which is a
concern in low traction conditions.
If you develop the right touch you can "float" every gear by just pulling
it out of gear as you come off the throttle, blip the throttle as the stick
passes through neutral and then apply slight pressure on the stick to
push it into the next lower gear. When you first start out you'll grind
(polish?) the gears a little, with practice you'll start to feel them
"roll" together, finally, you won't feel a thing. After a while, you'll go
months without missing a gear. If you do miss one, just hunt around gently
for a gear it will drop into, regroup and start up or downshifting again.
Use the same procedure to upshift but pause in neutral long enough to let
the revs fall to match the shaft speeds. (Engine wants to spin slower in a
higher gear.)
Some engine/trans combos are easier to master than others. For example,
Detroit Diesels are relatively light engines (inertiawise) so they tend to
drop revs more quickly, making it harder to float an upshift because the
engine drops revs so fast that if you don't get it out cleanly, you have to
blip the throttle to get the engine back up to the correct speed.
Caterpillar diesels are quite inertia laden so are very easy to upshift, as
you can go out for a sandwich before they slow down. Cummins stuff is
right about in the middle but no matter what you have, once you get it
right you will need the
clutch only for stopping or getting it rolling. It's a joke among truckers
that they only use the clutch twice (leaving and arriving, driving through
non-stop) on a coast-to-coast run but, seriously, it's not unheard of for
road trucks to have a million miles on a clutch because it never gets used.
(Same thing with brakes, if you pull someone else's trailer, you can get
by almost never using the tractor brakes.) Of course if you drive through
the night(s) you'll start to mess up regularly and wish you had an
automatic. Which by the way, is truckers' mocking slang for transmissions
with air buttons to shift the
auxiliary trans. The air buttons are referred to as "training wheels" by
the dying (actually, pretty well dead) breed of truckers who still prefer
to "mix sticks".
There's a pretty good trick, floating both transes at the same time, one
hand on each stick with your arm looped through the steering wheel while
you round a curve...
Once you are used to double clutching or floating, you'll never want to
drive any other way (like once you're used to your seat belt you feel naked
without it) but, surprisingly, while you can (and should) double clutch a
synchronized trans, it is (at least, I find it so) nearly impossible to
consistently float them, especially the smaller ones.
> any other driving tips are appreciated
Sure, most accidents happen within 10 miles of your home at speeds below 25
mph, so drive fast and never go home.
Regards,
JP
since i'm driving my truck more and more and i don't want to push its
limits.
>
> Haze
> M-43
> Vanc.,B.C.
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