Another '39 transmission ??

AzBob

AzBob

Senior Member
With my new to me '34 with '39 transmission now running, I took it out for a test drive and found it will not shift into 3rd (high) gear. Just barely starts into the 3rd slot then stops like something is blocking its travel to full engagement. :(

I am going to remove the tower and have a look for any thing obvious. Recommendations?
 
I would wonder if it has the proper 91A type 2/3 shift fork installed in the late type double detent shift tower used in the later 30s transmissions. The single detent tower used in the mid 30s will function with the 91A fork but has less to hold the transmission in gear positively. The early transmission tower used from 1932 through late 1935 will not work with the 91A fork as is. Folks have modified the early fork to work but it would require welding. I know it's been done but I don't know how well that mod will last.

If that's not the problem then a person would have to check out the synchronizer hub & sleeve components and make sure it's set up properly.
 
rotorwrench said:
I would wonder if it has the proper 91A type 2/3 shift fork installed in the late type double detent shift tower used in the later 30s transmissions. The single detent tower used in the mid 30s will function with the 91A fork but has less to hold the transmission in gear positively. The early transmission tower used from 1932 through late 1935 will not work with the 91A fork as is. Folks have modified the early fork to work but it would require welding. I know it's been done but I don't know how well that mod will last.

If that's not the problem then a person would have to check out the synchronizer hub & sleeve components and make sure it's set up properly.
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Third Gen is now selling the correct 3" fork to be used with an early top. Smart idea.
 
I appear to have the correct double detent shift tower. Have the tower off and can easily snap the synchro hub into 2nd gear by hand. No go for 3rd, even having all teeth aligned and tapping with a wood block, no go.

Looks like I will have to remove the transmission. Previous owner had been into it and maybe 3rd gear synchro hub not assembled correctly.
 

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Sometimes one of the little steel "pucks" (chicklets) in the synchro hub are popped up and then you can't engage 3rd. There isn't much else that prevents the synchro collar from sliding forward. You should be able to engage it back/forth (3rd/2nd) by hand.
 
AzBob said:
I appear to have the correct double detent shift tower. Have the tower off and can easily snap the synchro hub into 2nd gear by hand. No go for 3rd, even having all teeth aligned and tapping with a wood block, no go.

Looks like I will have to remove the transmission. Previous owner had been into it and maybe 3rd gear synchro hub not assembled correctly.
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AzBob said:
I appear to have the correct double detent shift tower. Have the tower off and can easily snap the synchro hub into 2nd gear by hand. No go for 3rd, even having all teeth aligned and tapping with a wood block, no go.

Looks like I will have to remove the transmission. Previous owner had been into it and maybe 3rd gear synchro hub not assembled correctly.
Click to expand...

To Dale's (Bored & Stroke) point, see that blocker (rectangular metal tab) on the synchro? Try to get the cluster to rotate and make sure the other two still there or not bound or jammed up. Report back what you find.
 
As per Bored&Stroked and Tim Ayers, I Checked all three "chiclet" shaped rectangular metal tabs. They didn't seem to be bound or jammed up. All three wiggle back and forth when moving the synchro hub.

Even though I have the teeth perfectly aligned, something prevents the hub from engaging 3rd gear splines. Can engage the synchro hub with 3rd gear synchro but no go onto the 3rd gear splines. :confused:
 

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AzBob said:
As per Bored&Stroked and Tim Ayers, I Checked all three "chiclet" shaped rectangular metal tabs. They didn't seem to be bound or jammed up. All three wiggle back and forth when moving the synchro hub.

Even though I have the teeth perfectly aligned, something prevents the hub from engaging 3rd gear splines. Can engage the synchro hub with 3rd gear synchro but no go onto the 3rd gear splines. :confused:
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There could be a problem with one or both of the expansion springs that hold the inserts outward. That would really require the disassembly of the synchro unit to inspect the parts. Also, for whatever it’s worth, in the last photo (showing the 3 location) it’s very evident that the 3rd gear synchro ring is pretty much worn out. When pushed against the cone of the input shaft gear, there should be a gap of close to 0.050” for the ring to do its job. There’s virtually no gap showing.
 
Looking at the photos, I too question why the syncro. ring it is so close to the input gear (3rd) teeth plus looking at the inserts and into the syncro. ring slot for the inserts it appears the ring has a raised area, which should not be there. Believe it is an incorrect ring.
I also believe its time for some disassembly to inspect the syncro.
 
Thanks Mac VP for your assessment. Terry,OH agreed, time for some disassembly and inspection.

Have a couple of issues with the engine that need addressed so might as well pull out the engine and trans at the same time. Thanks all for the replies.

Edit: Any recommended books for disassembly and repair of the 1939 transmission?


Edit: Just ordered Mac VP's L-1001 The Ins and Outs of Early Ford Transmissions Book.
 
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For the year 1939, Ford used that spring ring set up and the stamped detent plates that work with them. They didn't use it long before changing it over to the coil spring with ball bearing type detents. There are two different hubs depending on which slider detent set up it has. Later, after the war, FoMoCo went back to the spring ring set up. A person has to make sure all the pieces match the type of synchro it has.

Mac has given folks a heads up concerning quality problems with the brass blocker rings. Some have windows that are out of spec and the taper isn't quite right for matching the cone on the gear. Mac only uses the blockers that work so he is the best source for things transmission on early Fords.
 
Hal Beatty said:
Also, the picture of the #3 synchro insert appears to show a cracked or broken brass blocker ring...
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Bingo. Great catch. Be sure to purchase any parts especially brass blockers from Mac VanPelt as there are many inferior parts available.
 
KiWinUS said:
Bingo. Great catch. Be sure to purchase any parts especially brass blockers from Mac VanPelt as there are many inferior parts available.
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Second souring from Mac VP. A little searching, one can still find NOS ones. They used the same one for quite a while in various transmissions. They also fit as they should.
 
Hal Beatty said:
Also, the picture of the #3 synchro insert appears to show a cracked or broken brass blocker ring...
Click to expand...

Thanks Hal Beatty for spotting that crack. You have a sharp eye.
Found I could slide a .010" shim into the crack.

Will definitely source parts from Mac VP.

Thanks all for the help.


Bob
 

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