The first car and truck transmissions required "double clutching" to
syncronize the gear speeds when shifting gears. One nickname for such a
trans was "crashbox" which described the sound made when a less than
proficient driver made a shift. With the advent of gear syncronizers, this
was no longer necessary to prevent grinding the gears during a shift due to
a speed miss match. When I was a kid I got some experiance on a 1940 Ford 1
ton which had a crash box. Ain't no doubt when you miss a shift.
With a syncro trans it is not necessary to double clutch. However it is a
good skill to have when the gear syncronizers start going out. Double
clutching when done correctly, makes shifting on older transmissions,
smoother and less stressful on the transmission. When I was trained to
drive commercial cargo trucks, I was taught to D-C and when I have to work
the gears in the mountains it really helps. When I am working my dueces or
5 tons under load I usually D-C. I also teach to shift with fingertip
pressure. People tend yank the shifter between gears when they are learning
and this leads to the early death of your trans.
Double clutching does cause more wear and tear on the clutch and throw out
bearing. When you shift, it needs to be with a smooth, gentle, loving
touch.
Then of course, when you get alot of experiance, and are really smooth, you
can shift without the use of the clutch. But that's another story.
This, of course, is my opinion.
Randy Orpe
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