1939 Ford 3 speed top loader help

J

joshhirst13

Member
Hey guys. I’m finishing up rebuilding my 39 3 speed top loader & I’m having issues with the gears getting tight & locking up when I tighten the bolts down on the rear bearing retainer. I can’t for the life of me figure out what is happening. The gears rotate smoothly & work properly, but as soon as I tighten the bolts on the retainer everything locks up. Any help or suggestions would be great. Attached are some photos of the rebuilt gears. Maybe I did something wrong. I’m using a 1933-34 bearing retainer. I tried using a thicker gasket & that didn’t help. I’m not sure what else to do.
Thanks
Josh
 

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I do not see the main shaft rear oil baffle 68-7080 although there appears to be something there that may be too thick. Before installing the rear bearing retainer (motor mount) make sure the rear bearing is seated so the outer retaining ring is against the transmission case.
 
There should be a ring on the rear bearing that limits the bearing travel at the rear. The baffle was already mentioned. There are several main shafts for the early gear boxes so a person needs to confirm they have the one that works with the parts at hand. There could also be a problem at the front of the main shaft where it joins with the input shaft. Something certainly isn't stacking up right if it's locking up. A verification of blocker ring fit to all the other parts may be needed. Some of the new synchro blocker rings don't have correct dimensions.
 
Do you have a picture of the input shaft? I disassembled a '39 type transmission which had been assembled with an earlier '32-'38 16T input shaft with the narrow synchro land. It was locked up tight until I loosened the rear mount bolts, obviously had never run this way. Paul
 
Can you slide first gear to the rear of the case ( into reverse ) and take a picture?
Did you replace 7069 washer ? It comes in two sizes , and I can see your rear oil shield but I think its on backwards . The rounded edge goes towards the front . That could be .020-.030
If wrong .
 
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Im curious, do all 16 t inputs have the smaller syncro ?
Never mind , brain started to work . Slow but working .
 
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Another thing I recently came across that may help. I replaced the rear main bearing and discovered that it was wider (thicker) than the previous bearing by about 30 thou. this caused the system to lock up when I put the universal joint on and tightened it up.
just a thought.
Dave
 
Charlie Schwindler wanted to mention the blocker rings may also have problems. Make sure the 3, U-shaped openings on the syncro hub side are of the proper width and the rings don't have another problem such as deformaty. For the 81A-7107-B blocker the 3, U-shaped openings are 0.636" W & 0.305 +/- .002" deep
 
Had exact same problem with ****** I got with a boat load of parts. PO had "rebuilt" it with all new or like new parts--looked brand new. But when rear bearing holder was tightened down it locked up. After MUCH searching and head scratching, on page 298 of the Green Bible at the bottom of the page there is a footnote to not use 81A-7071 thrust washer with main shaft 51A-7061. That was the problem, the washer was on the shaft, took it out and it spins freely like it should. Check all your parts, this very well could be your problem if you have used a collection of parts to assemble your ******. Good luck.
 
I also had this same problem during the recent assembly of a '39 3 spd transmission. What I found was the rear ball bearing was not pressed completely in place on the main shaft, possibly due to a slightly tighter than normal press fit of bearing to shaft, and also due to the fact that I had to assemble this bearing last, after everything else was in place in the gear box.
 
Ken/Alabama said:
Did you check the clearance between the 2nd gear and the thrust washer behind 2nd gear with a feeler gauge ?
Click to expand...

This basically checks the 'stack-up' clearances of the main shaft. You have to assemble the 2nd gear on the shaft (with the thrust washers), along with the synchro hub and put the snap-ring in to lock it down. Then you check the clearance. The closer you are to .004 the better.

On a lot of my setups, I try to get down to about .0025 to .003 (under the spec). This tends to help prevent the infamous "popping out of second" issue that so many of these transmissions seem to have.
 
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