Questions on f1 three speed trans

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ronzmtrwrx

Member
I am picking up parts as I come across them to put together a trans for my 39 conv. I have a case that's cracked beyond use. I have a double detent top but it has the early fork which someone ground to use on the later synchro. I have a 46 side shift trans with decent guts. I just came across a light truck trans that is hooked to an 8BA that I'm sure is stuck. My questions are can I use the truck case, my 46 guts, the shift fork from the truck in my top, and my rear components for closed drive to make a trans. What would be a fair price to offer the guy. I feel like its not much more than scrap if I can't look into it to check it out before buying, or am I just being a tight wad?
 
The light truck trans will be your foundation for this....as long as it's the light duty 3 speed up thru 1952. Assuming the case is good ( you won't know til you get it apart and clean), the next question is: is the truck trans a 48-50 or is it a 51-52?

If it is the 51-52 version, you would have to use those type gears to complete it. Which would mean the 46 passenger donor gearset would do nothing for you. How to know ( if you're not familiar with these gears) ....count the teeth on the big end of the cluster gear. If 28 or 29 teeth, its the 42-50 variety, and you'd be all set.

If the big end has 27 teeth, its the 51-52 variety. Of course, if that truck gearset is in good condition, you could just work with that.

The 46 passngr trans could offer up all that you need if the truck trans is the 48-50 type. There could be some small details re matching up the synchro and some thrust washers, but that is easily resolved.
 
In theory, you would have almost all that is needed to make a complete trans for the 1939 except for the 39 clutch shaft/arm plus the 1937-41 trans rear mount. Drake sells a repro 39 clutch arm for about $25 but you would need a 32-39 type clutch cross shaft also. The ratio of the 1946 trans would be either 16/28 or 15/29. Also, If the pickup trans is a 1951-52 with the 16/28 gear set, none of the gears or main shaft will work with either 46 gear set. The entire open drive pickup trans top, if in good condition, will work in the 39 as-is with only the possibility of a little bending of the shifter handle.
 
Thanks, guys! I didn't mention that my cracked case has the clutch arm and cross shaft still in it however there is some movement of the outer arm on the cross shaft. What I really need to do is pull his top and count the gear teeth if possible. Thanks again for the input.
 
Nope, the modified fork will not work. I think the 91A fork is now being reproduced but originals are still out there and the light duty commercial 3-speed boxes from 39 through 50 are all good candidates. Many times you can find a decent box with the shift tower still installed and it will will have the 91A fork in there if it's manufactured after 1939. Get Mac's book. You won't regret it.
 
Thanks for all the feedback. I wasn't planning on using the ground fork, I was just stating I had the right top, it just needed the later shift fork. I had the guy to look for the serial number on the case, but he couldn't find any numbers, so as of now I still don't know the exact year it is. I need to go for a drive anyway. :-)
 
I've had this trans sitting around forever, I got it in a purchase of some other parts. It sounds like just what you are trying to build? Side shift, closed-drive. Don't know what the differences are in the forks? PM me if interested.
 

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ronzmtrwrx said:
Thanks for all the feedback. I wasn't planning on using the ground fork, I was just stating I had the right top, it just needed the later shift fork. I had the guy to look for the serial number on the case, but he couldn't find any numbers, so as of now I still don't know the exact year it is. I need to go for a drive anyway. :-)
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The shifter top and a good case are the main parts you need from the 42-52 light truck trans as long as you have a good 46 side shift gear set. The pickup top will have the correct wide fork unless someone has incorrectly stuck something else on. Look for the a "91A" marking on the fork. Any good bearings, syncros or compatible 42-50 gears are a bonus.
 
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