2nd to 3rd shift feel
07-24-2012, 08:04 PM
#31
Originally Posted by rob-2' timestamp='1343162186' post='21885912
[quote name='Saki GT' timestamp='1343144400' post='21885030']
[quote name='rob-2' timestamp='1343009806' post='21880610']The syncros were optimized for high rev shifting. I've experienced less ideal shifting below 4K. To which I alter my style slightly.
[quote name='rob-2' timestamp='1343009806' post='21880610']The syncros were optimized for high rev shifting. I've experienced less ideal shifting below 4K. To which I alter my style slightly.
It might be for this reason why I find clutch-less driving difficult below about 4k so I never do it anymore.
[/quote]
The relative difference in speed is around 1k rpm between changes, regardless of the rpm. I'm not saying you're wrong, but I'd love it explained to me exactly how a shift from 6k to 5k differs from a shift from 9k to 8k to a synchro. I assume there's more kinetic energy to deal with, but I'm not sure.
[/quote]
I will see what I can dig up. I do believe it was teeth and syncro related.
07-25-2012, 05:45 AM
#33
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The relative difference in speed is around 1k rpm between changes, regardless of the rpm. I'm not saying you're wrong, but I'd love it explained to me exactly how a shift from 6k to 5k differs from a shift from 9k to 8k to a synchro. I assume there's more kinetic energy to deal with, but I'm not sure.
As far as kinetic energy, at higher speeds a change of 1k RPM is more energy because the kinetic energy is proportional to the square of the speed.
http://en.wikipedia.org/wiki/Rotational_energy
In addition, the when shifting up from 2nd to 3rd you're not going to see a constant RPM drop. With constant vehicle speed, it'll have to drop by [1 - (3rd gear ratio)/(2nd gear ratio)].
(1 - 1.481/2.045) = 27.6%
So if you're at 8k RPM and you shift, it's losing 2,200 RPM. If you're only at 3k, it's only a change of 830 RPM. Using this speeds, this indicates that shift at higher RPM requires 7 times the energy reduction of the low RPM shift.
However the synchros aren't the only thing doing work. I'm sure there are other forces at work which are decelerating the transmission which are at work as well as the perception (at least for me) that this shift event should occur in constant time.
07-25-2012, 06:02 AM
#34
One of the best things in ever learned in regards to shifting is that it is two completely separate actions. Pulling the shifter out of second is one action, and putting it into third is another. It can be done relatively quickly, but god forbid you go from second straight to third. You go from second to neutral AND neutral to third.
01-15-2013, 02:56 PM
#36
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Originally Posted by SpinningHigh04' timestamp='1343152638' post='21885419
I also find that shifting above 4k helps with the "notchiness", in the AM on a cold motor I take it really easy on the car and shift at about 2500 rpms for about 2-3 miles till the car somewhat warms up, I am just anal tho.
My 2-3 shift is very notchy but im pretty sure my synchros are shot on that gear. Weird thing is my 4-3 downshift is perfect every time. I can only feel my gears grind only from 2-3 if i try and shift it even at normal speed. Normally i take it out of second then hesitate then then go third. Mine most likely needs a rebuild.
03-12-2016, 09:42 PM
#37
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so a little notchiness is normal? ive experienced this in my 6 speed 2.4 accord as well after i did the 5spd conversion to 6 spd. Did a tranny oil change, made no difference. Sometimes i think the notchiness is because of cold weather. also theres a clunking sound once i put it into gear. started to think it was normal...
then i bought my s2000 and noticed the same results...
idk what is with 6 speed, but i never had any problems like these with 5 spds. could it be im shifting wrong?
anyone want to chime in?
then i bought my s2000 and noticed the same results...
idk what is with 6 speed, but i never had any problems like these with 5 spds. could it be im shifting wrong?
anyone want to chime in?
03-14-2016, 01:46 PM
#39
I give it just the right amount of time for the shaft to slow and the cogs to naturally reach the same RPM before shifting up.
Paying attention to the feel of the upshift helps to determine the duration of the time it takes for the shaft to slow down appropriately to mesh.
After a while, it becomes a matter of habit.
14 years and every gear still feels perfect for my tranny.
If a person matches leaving the lower gear with properly timed throttle lift, and pressing the selector into the next gear perfectly timed and with light pressure, the car can actually be smoothly shifted without ever pressing in the clutch... not that it's a good idea.
Paying attention to the feel of the upshift helps to determine the duration of the time it takes for the shaft to slow down appropriately to mesh.
After a while, it becomes a matter of habit.
14 years and every gear still feels perfect for my tranny.
If a person matches leaving the lower gear with properly timed throttle lift, and pressing the selector into the next gear perfectly timed and with light pressure, the car can actually be smoothly shifted without ever pressing in the clutch... not that it's a good idea.
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