Technical Putting Zephyr gears into a Ford box which mainshaft?

Im putting 26T Zephyr into a 78 series Ford box. Which mainshaft is correct? Year or part number please? Or is any late 39 and up okay?

 

I think any shaft 39 up will work. I have a 40 side shift with 25teeth LZ gears. I know the main shaft is 40 ford. But wait for others to tell you. I'm no expert so don't take my word for it.

 

You would use the late 39 - 48 main shaft - 81A-7061 - with pin-hole (with a torque tube) - or the 46-48 51A-7061 (no pin hole), or the 42-44 open-drive main shaft - 21C-7061. You'll use the regular Ford synchro assembly --> 01A-7124-A or 51A-7124. I prefer the 01A-7124 syncho assembly - just have had less issues with them.

One thing to think about is the fitment of the 2nd gear to the main shaft - usually they are too loose (in my mind). I'd have Charles Schwendler (on Fordbarn) do a custom bushing to your specific main shaft - the fitment ends up dead nuts . . . and he'll shim the 2nd gear end-play correctly. These two things (along with a main shaft that is NOT worn on the caged roller bearing surface) will have a lot to do with a transmission that doesn't pop out of gear in 2nd (when you wind it up and let off the gas).

 

x2 on Charley Schwendler.

 

Thanks for the responses guys. These gears are NOS, so i dont think shimming will be needed but thanks for the suggestion too.

 

Is anything else needed for the pin hole style, a extra washer? I was trying to read up on it

 

FWIW, the November '51 issue of Hot Rod Magazine had an article including charts, part numbers, and illustrations on this conversion starting on page 22 which might be worth researching.

I've never done this myself so can't vouch for the accuracy of this info when published or about any improvements or upgrades to it since.

Ed