Topic: 78 CB750 F3 Transmission Question

[SD750F]

I have a couple items not address or not address properly in my manuals for my 78 CB750 F3 engine. First it has to do with the Gear Shift Fork Shaft. Mine has a duvet or drilled hole only on one end and a flush end on the other. Which way does it insert in the case? With the hole inserted inside the case, or pointed out into the shifting mechanism cavity?

Second as indicated in the picture below, the far left gear, or drive gear to the final gear should have an offset as indicated. Mine is not as indicated with the slight recess below the gear sides to the inside hub sides on both sides??? So I am considering that there is no right and wrong side with my transmission contrary to the drawing in the K8/F3 Honda Shop Manual???

Thanks,
Scott

[SD750F]

Bump... Hoping a mechanic reads the message and replies.

[bryanj]

If there is no difference and it was working it must be ok, as the F3 did not exist in UK i cannot give you 100% definitive advice but i would check a parts list and see if the original part number has been modified ALSO check the vin/engine numbers and make sure its an F3 not a late registered F2

[bwaller]

The shaft end with the hole faces out, there is a hook on one of the "plates" (involved with the shifting mechanisms) that fits in the hole to keep that shaft in place.

On earlier model transmissions (can't say for sure the F3 is the same) the outside of each tooth of that gear there was a slight cut. It's not really evident but if you have calipers you'll see it is slightly offset. The side with the largest offset faces the neighboring gear.

[bwaller]

Hey SD,

Just checked and I do have an extra F3 tranny, and besides that gear having five more teeth, has no cut like the earlier items. I did a quick measure and I don't see any sign of offset either. Orientation shouldn't matter IMO.

[SD750F]

What I have decide to do to make sure I have the last gear installed correctly is to look at the ever so slight tooth wear and place it back in the second transmission shaft the same way.

And I did additional research and found the same mechanical requirement for the fork shaft with the hole pointing to the shifter mechanism cavity.

Thanks to all for helping me make sure I put everything back together correctly. This is my first tear down and being an engineer I want to do everything the best way I can. I read my three manuals multiple times, then reread them to make sure I am doing everything correctly. But they never address all the tricks a good mechanic will use... I assure the members here, who respect the SOHC that I will NEVER use the advise of my "experienced" neighbor who insisted that I just run my engine with known glass beads inside the case because "They will grind up and be filtered by you oil filter anyway" statement. I knew then that he didn't have any respect for engines, technique, and doing things right. And guess what? He owns 2 CB750s!!! For that I will shed a tear...

Scott

[SKTP]

Sorry to drag this up from 2008...but I am rebuilding my 1978 CB750K's tranny right now and that diagram is exactly what I have been searching for.

What manual is it from? Does a manual like it exist for a 78K?

And actually, isn't a 78 CB750 F3 tranny almost the same as a 78K's? Maybe I'll just use that diagram.....?