Transmission Questions

[Cartravel]

I just finished rebuilding my first Ford 3 speed for a '40 pickup project. I found the Vanpelt book to be indispensable and also the information from Rumble Seat was also helpful (http://www.flatheadv8.org/rumblest/gears.pdf). I picked up a bunch of transmissions and parts several years ago from a guy I found in northwest Kansas. There were some parts alone, some half rusted, a combination of open and closed drive, early and late. You name it. They were mostly from trucks, so all are top loaders. One is so rusty I have yet to get the countershaft out after filling it and soaking in ATF and acetone for months. After going through all this stuff and comparing with the literature, I still have some questions.

For the blocker synchro trannies, Vanpelt mentions 2 different variations of the 2nd gear and synchro hubs. I'll post my measuremnts, so this will make sense. The early ones have the synchro with 3 balls and springs (0.935), 2 washers (0.185 and 0.065) and a thin 2nd gear (1.582). These total to about 2.77 inches. They fit in a space of 2.78 between the clip and the shoulder of the spline. The spline length is 2.913. The other has the later synchro with the two hoop springs (0.990) and wider second gear (1.656), totaling 2.65 and fit in a space of 2.66. The spline length I measured was 3.065. I found a 3rd variation which was 2.605 long with a spline of 3.095. It was like the first arrangement, but without the 0.185 washer, which agrees pretty well with the length measurement. Is this last one a known variation, or have I picked up some sort of odd ball? I was also wondering, since the difference between a late synchro and early synchro is about the same as the width of the 0.065 washer, can you substitute the thin synchro and washer for the later wide synchro?

I also wanted to ask about repairing the shifter shown in the photo. I would naturally braze it, except I'm concerned about screwing up the threads. This seems to be a common problem due to the pin hole, I have another where the crack caused a chunk to fall off. These are both the desirable late shifters, so I would like to salvage them if possible.

Sorry this was so long winded, but TIA fo the help.
Larry Young

[Terry,OH]

If you remove the internals from the cracked shift tops they will fit into the double detent 81A shift top with the small 3-4 shift fork. These tops are not as $$ as the later top since the wide fork is the $ item.
The 81A syncro hub has the larger holes (3) for the springs and balls. I believe the 91A hub does not have the holes and uses the wide opening in the hub for stamped steel bars and the (2) large, thin, spring on each side. There is a third hub with small thin openings and uses cast bars. Of these the 81A hub is mostly preferred using the (3) thick steel bars, balls & springs.
Check out the back of Mac's book (there are different shafts also) I believe you can substitute one hub for the other and use different thrust washers to get the proper tolerance.

[D. Jones]

If I were going to try to repair the transmission top I would grind a small V in the crack and then clamp it tight and braze it as you suggested but stay away from the threads. Next I would clamp it to the face plate of my lathe center it and then true the OD carefully and then turn a collar to a .001 press fit and put it on the cracked area below the threads. Done properly the repair would be strong and very hard to see.

[Cartravel]

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I thought this photo might clarify the 3 types of shaft and gear arrangements mentioned above. The top two use the narrow gear and synchro hub. The bottom one uses the wide gear and hub.