Manual Transmission Question
 

Sometimes you get those really buttery smooth shifts and other times it feels "notchy." When you move the shifter and you feel resistance shifting into a gear, what are you actually feeling?

You're feeling the synchros slowing down or speeding up the input shaft of the transmission to match the output shaft based on the gear ratio you've selected.

Double clutching just right eliminates the resistance you feel caused by the synchros matching the shaft speeds and the lever will practically fall into place. In practice though it's not usually worth the extra effort, the synchros are doing their job.

Shifting slower should reduce some of the resistance you feel as well as prolong the life of the synchros, let it slide into gear instead of jamming it.

Edit: I'm not 100% sure on the notchiness factor, like it 'chunks' going into third for me sometimes so I don't want to say anything incorrect on that front.

Edit 2: Quickly found this post:
Seems good to me.
http://www.standardshift.com/forum/v...p?f=10&t=14659

Check for clutch drag. A dragging clutch can kill your transmission within only a few shifts as the synchros are fragile. It doesn’t matter what they are made of or if they are double or triple synchro, they will be ruined if the clutch drags, period.

http://www.jackstransmissions.com/pa...kills-synchros

Does this help?

It helped me.


https://www.youtube.com/watch?v=aAWx...ature=youtu.be

I would not say that statement is true.
I have shifted my trans literally hundreds of times with NO clutch, and it is fine.

But yes a dragging clutch can make poor shifts hard on the synchros and will wear things out faster.
Most of the time we feel a grind when shifting is because we are not fully disengaging the clutch.
That is a result of making very smooth shifts most of the time by rev matching.
Then our habits develop to just barely press the clutch enough