id say sort of related.

i had two issues going on.

1. there was some play in my clutch causing the pressure plate to not fully engage/disengage.

2. I developed a bad habit of “skip shifting” from 4th to 6th.

the former was addressed by adjusting the free play in the clutch master cylinder. 1/2” to the spec 1/4” made a significant difference.
the later did help “clean” the burrs created from skip shifting.

after both issues were addressed the transmission is sweet as a nut! Really spectacular!!

for reference, when rowing 5th/6th. Car cold. Clutch in. Firmly shift back a forth between the 2 gears. You can feel the synchros turning as you do it. It may stick a few times and not want to go into gear. Just take your time and try to feel through it.

 

How do you feel synchros moving with engine not running ? ^^^^^
quote from Car A :Since we got this far, lets hopefully kill it off.

You do not start the car. The idea is to NOT have any lube on the gears. Let it drip off overnight, so at that point you definitely don't wanna do anything to circulate it.

The idea is to debur the syncros. Force them to engage repeatedly, dry. So clutch not pressed means more resistance to engaging, more deburing.

I'd do it e brake not on, brakes not pressed.
But you may have to use clutch on the first time to get into gear. Then I'd do remainder without using clutch

 

give it a try. As you’re working through the 100 shifts, each shift is a little different. Some times you get 5-6 smooth, then you’ll get a sticky one. I assume that is a burr on a synchro. And it will come back around again. So I’m assuming what I was feeling is the synchro rotating as you back and forth between the gears.

I could be wrong but that’s what it felt like to me.

 

If nothing is turning, engine, wheels, the syncros aren't turning either. So nothing to 'come back around'.

But the syncros won't initially be perfectly aligned to engage. They kinda slide a little, rotate slightly, to align. As each ramp shaped tooth engages with its partner.

With clutch not pressed, and car stopped, engine off, there will be resistance to them rotating to engage.

Once they align the first time, they will generally be already aligned on subsequent dry shifts.

But with everything stopped, there is baked in reluctance for things to rotate to engage.

Think of it like this. One side of syncro connected to wheels (through trans gears, drivetrain,etc). Other side to engine (through gears, clutch, etc).

With everything stopped, clutch not pressed, engaging these syncros will require taking up all slack in each end of those systems, and still they won't have enough room to perfectly mesh.

Even if you press clutch, getting syncros to mesh requires all the trans stuff between syncro and clutch to rotate, dry, as well as pressure plate.

So there is weight behind these things, so syncro teeth ramps will rub against each other, trying to mesh. Clutch not pressed just means more stuff to move to mesh, more resistance, more rubbing. More burr removal.

The amount syncros need to rotate to mesh when stopped like this is always gonna be less than length of each tooth. A miniscule amount. There is nothing making them rotate other than your shift lever force and their ramped teeth.

 

This is an interesting animation. Borg-Warner synchro system.