Double clutching and Synchromesh



In a nut shell,

If you find you have to double clutch, either your running the rpms up to high
in the current gear before you shift or your synchros are worn out. Double
clutching simply allows the motor RPM more time to decrease and applies external
breaking (engine drag) to the pinion shaft. As soon as you push the clutch in
again, the transmission and the engine spinning speeds will differ, but both
have now slowed down. You double shifters. Try waiting two second in neutral
before you shift and tell me if it has the same effect. Two seconds is about the
time it takes to double shift. If your shifting at the right time and rpm, you
should barely feel the shift ring leave one gear and move onto the next. If your
feeling that snap as you leave the gear, you rpms are much to high, shift

The gear grind is most common between first and second because of the typical
higher rpm you used to get through the intersection, that's why many people
start in second and forget first altogether. I know someone will say that
starting in second requires more clutch slip to get started. Ok, you'll get 25
thousand miles instead of 35 thousand miles out of your clutch. It's easier to
replace the clutch than the syncros and worn gears. If your having problems
getting into first gear, your clutch cable needs adjustment or your first gear
synchro is shot, or your engine idle is too high.

As you shift from one gear to the next, you'll find that if you apply an
increasing pressure into the next gear, or you hesitate in neutral for just a
second, you'll give the synchro time to slow down the spinning mass and the gear
will engage with out a problem. THE SYNHRO DOES NOT ALIGN ANYTHING, it's a
rotating mass brake. If as you apply the pressure, you get grinding until the
gear is engaged, your synchro is bad. Ever notice you can shift through all the
gears with little problem when the engine isn't running.

These synchros suck. The are made of a hardened steel with an applied coating.
As the coating wears off, the result is a hardened shift ring hitting a hardened
synchro ring with very little breaking resulting. The highest rpm difference
between shifts is between first and second. Page 1-5 in the manual gives the
gear ratios. Most manual transmissions use brass or other soft material. I would
guess the second gear synchro has about a five thousand mile service life,
depending on how hard (fast) you shift you shift between gears.

Just my opinion

Scott Moses..

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