Topic: Closing the case - verifying shifting.

[eatpez]

I'm getting ready to button up there case on my F1 rebuild and I'm nervous about the transmission being correct.

Are there any tips or tricks to check everything is captured and working properly? I searched the forums and didn't come up with anything.

I did a test closure and I can rotate the shift drumb around to all the gears pretty smoothly. Does this suffice?

I removed the clutch and I assume the crank won't turn the sprocket shaft without it.

I may be being paranoid and perhaps just looking for some reassurance because I'd like to avoid splitting the cases again once closed (at least for a few years lol)

Hoping to get on the road soon...

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[PeWe]

You need to rotate the final shaft (front sprocket) and clutch to help getting all gears in.
I usually assembly everything in the lower case and try all gears. Top case mounted last, final shaft hanging in the oiler plate

[evanphi]

You can use a drill to spin the final drive, and then use your hands to run the shifter. Just make sure you have a clutch set up also!

[PeWe]

But the gears will usually work fine. It's normal to worry about the gearbox before closing the cases
One hing that can be missed is wrong mounted forks. 1 or 2 of them flipped. The pin that is guided by the groove in the shifter must follow with good angle in the groove. You'll see when wrong.

The shaft the forks rides on, hole in the shaft outwards!
Hollow side inwards will be a problem when you need to assemble the gear shifter mechanism.
Note! The 4 countersunk bolts the fasten the bearing holder must not be too long. I replaced these with allen head versions of correct lenghts. Too long will hit the gear on the other side.

[slikwilli420]

I just put my race trans back together and was able to shift through all gears with just the shifter, and without rotating the countershaft. Mine was ISF treated so that made it far easier to shift. PeWe is right about the forks, make sure they are in the right locations and the shaft has the hole outwards. The Hondaman book was invaluable for this process and lays everything out so it is very easy to follow and understand.

[rotortiller]

You also want to look at dog engagement, smooth shifting is not the end all.

[70CB750]

I had a quite a fight with the transmission on Red, but it was never the gears.

First it would shift up to 3 and that was it.  I ended up riding without the Neutral lock cam for 500 miles - doable, just hard to find the neutral.  Also doubled the zddp additive in transmission oil, it just had to get broken in.

Than one time I did not have a gasket for the transmission cover, so I used just silicon to seal it.  Found out the bolt next to the shifter was binding the cover and the shifting lever would not move back.  That issue went away as soon as I used paper seal under the cover.

Make sure all moving surfaces of the shifting linkage are smooth, I polished them on a buffer.  Also lube everything well and use good oil in the transmission, like Spectro 20W50.

[eatpez]

Well, thanks for all the tips. I got her all closed up tonight. Going to do the shifter assembly and then call it a night!

Hey Hondaman, if you're reading this, I'm going to need the head back real soon now!

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[eatpez]

Well, something might be up. The clutch is out, FYI.

I tested shifting through all the gears and it's not going smoothly. I expected a firm click into each gear without having to move the final drive at all but no bueno.

I doubt it has anything to do with the shifter assembly because I get the same result turning the drum by hand.

I'm bummed. I'm sure this isn't something that will "resolve itself" so I guess I get to open up the case again...sigh.

Any advice?

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[PeWe]

The end bearing for the main shaft is not there. This will affect how the gear box works since the shaft is hanging.
Only thing you can do wrong is flipped forks. Except forgetting the bronze stuff inside some of the gears, no bearing locks  for 3 of the bearings with grooves vs grooves in upper case. Later on flipping the washer under the clutch center nut. This washer is like a spring, convex shape with its curve outwards.

Below 2 different CB750 builds. I flipped the middle fork which I noticed when gearing did not work that well. I saw it too and corrected it.
Arrows show the differences
The pin that must follow the groove has a wrong angle and will not work.
Visible fork is the thinner on this side.
Shape of the part where it glides on the shaft is different too

You might have done it right. Open now is better than find out when engine is the frame

[eatpez]

I cracked the cases back open, cleaned everything up and started again.

Nothing obvious was out of place and but I did pull everything and reassemble one step at a time. One thought was perhaps the neutral switch was over torqued but it felt like more than extra resistance.

I dry fitted the cases twice, including the bearing retainer to test all was well. I kept it in 5th for closing the cases as this seemed like the easiest way to keep the center fork lined up.

I'm happy to report all is well. I put the clutch and the new rings on the pistons tonight. Onward!

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