2nd won't engage?

PeteVS

PeteVS

Well-known member
A few years ago, I put together a "39" trans with what I thought were all the right parts. Later synchros, later shifter top and a 29 tooth cluster, 15 tooth input shaft. Yesterday, I got everything together, engine running and I tried driving up the street. First gear- it's all right! Third gear- it's all right! Reverse gear- it's all right! SECOND GEAR- NUTHIN!!
I took the top off today. The center of the groove on the synchro wants to be about a 1/2" ahead of the center bolt hole for the top. With the shifter lever in second, the center of the fork only goes back to about 3/4" ahead of that center bolt.
It's hard to read the part number on the shifter fork but it appears to be 68-7230. Is that right? Could the shifter rail have the hole in the wrong place?

I have to figure out how to load two more pictures...
 

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Does the slider work correctly by hand? I'd move the slider into the 2nd position, then measure where it is at in reference to a known datum, then manually move the shifter top into what should be 2nd and see where it is at?

I've never had this issue, but I've also made sure I had all the correct parts before building.

If you continue to have drama, let me know and I'll measure a double-detent 39 style top (I have one loose).
 
PeteVS said:
A few years ago, I put together a "39" trans with what I thought were all the right parts. Later synchros, later shifter top and a 29 tooth cluster, 15 tooth input shaft. Yesterday, I got everything together, engine running and I tried driving up the street. First gear- it's all right! Third gear- it's all right! Reverse gear- it's all right! SECOND GEAR- NUTHIN!!
I took the top off today. The center of the groove on the synchro wants to be about a 1/2" ahead of the center bolt hole for the top. With the shifter lever in second, the center of the fork only goes back to about 3/4" ahead of that center bolt.
It's hard to read the part number on the shifter fork but it appears to be 68-7230. Is that right? Could the shifter rail have the hole in the wrong place?

I have to figure out how to load two more pictures...
Click to expand...
514928
 
Pete,

It looks to me you've got the wrong forks. The early double detent tops were used with some transmissions that still had the early gear set and synchros.

If you have using the later, improved synchro set up, like someone mentioned, the forks you need are the 91A-series forks.

One last thing to check: When you put the top on to the cluster, you made sure the cluster was in the neutral position, correct?
 
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Thsnks folks! Gotta round up a different fork. At least I won't have to pull the engine to get the trans out.

Just looked at Mac's web page. 91A-7230 isn't available. What are the differences between the 68 and the 91A parts. Are there synchro sleeves to match each?
 
PeteVS said:
Thsnks folks! Gotta round up a different fork. At least I won't have to pull the engine to get the trans out.

Just looked at Mac's web page. 91A-7230 isn't available. What are the differences between the 68 and the 91A parts. Are there synchro sleeves to match each?
Click to expand...

I'll get a picture of the 91A forks and the corresponding synchro later. Mac VP is the go for trans parts. He'll have what you need.
 
PeteVS said:
A few years ago, I put together a "39" trans with what I thought were all the right parts. Later synchros, later shifter top and a 29 tooth cluster, 15 tooth input shaft. Yesterday, I got everything together, engine running and I tried driving up the street. First gear- it's all right! Third gear- it's all right! Reverse gear- it's all right! SECOND GEAR- NUTHIN!!
I took the top off today. The center of the groove on the synchro wants to be about a 1/2" ahead of the center bolt hole for the top. With the shifter lever in second, the center of the fork only goes back to about 3/4" ahead of that center bolt.
It's hard to read the part number on the shifter fork but it appears to be 68-7230. Is that right? Could the shifter rail have the hole in the wrong place?

I have to figure out how to load two more pictures...
Click to expand...

91A- (1939) Arm ...........

512604



Your "68" Arm (1936)..........

514928


Considering the angle, it surely looks different to me. In fact, yours looks like it has maybe been cut & rewelded?


Another 91A ....... Does NOT resemble yours.


452923



Coop

.
 
There is a good chance your "68" fork has had the tips of the forks ground open from 2 7/8" to 3" to fit the later synchro sleeve. This seems to be a common way to build a '39 trans in times gone by, however the offset of the forks are different as you have discovered. Finding the correct 91A fork will take some doing, search swap meets and get a want here on the 'Barn.
Good luck, Paul J.
 
PeteVS, can you post a picture taken at the open top of your transmission that will show us the gears that are in your transmission. The 68-7230 fork is definitely not correct for use with the '39 to '48 type gears, but it could have been modified to fit the 2nd/3rd syncro collar. As others have already mentioned, 91A-7230 fork is correct for '39 and later gears.
 
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JM 35 Sedan said:
PeteVS, can you post a picture taken at the open top of your transmission that will show us the gears that are in your transmission.
Click to expand...

Here's a picture of the gears. It was taken after the trans was shifted into second gear and the top was lifted straight up. Note that the sleeve has stopped about 1/4" shy of the second gear. I assume that it should have gone solid against it.

Mac lists the 91A-7320 but he doesn't have stock.

(I think I remember who I got it from- another Barner. But, that was YEARS ago.)
 

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Question: Would my 68-7320 work in my trans with a "single detent" top assembly and the synchros I have now. It appears that the fork has been ground out to fit the later synchro as stated in post #9 above. I'm pretty sure I have one of earlier tops lying around.
 
No, the groove on the ‘39 style synchro, like you have, is to the rear and the earlier synchro sleeve the groove is in the middle, so the early fork will not pull the late synchro sleeve fully back to the second gear position. Look in the swap meet section, there is a user that was selling modified forks. It might be what you need. https://www.fordbarn.com/forum/showthread.php?t=322823
 
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PeteVS said:
Here's a picture of the gears. It was taken after the trans was shifted into second gear and the top was lifted straight up. Note that the sleeve has stopped about 1/4" shy of the second gear. I assume that it should have gone solid against it.

Mac lists the 91A-7320 but he doesn't have stock.

(I think I remember who I got it from- another Barner. But, that was YEARS ago.)
Click to expand...

Okay, you definitely have the later gears and syncros. I can see why it was not going into 2nd gear based on the position of the collar/sleeve. That's typically one of the reasons why the 68-7320 fork does not work even when the internal dimension of the fork is ground or reshaped to fit the later syncro 2nd/3rd gear collar.
I think your best bet would be find a complete and correct double detent '39 type shifter top with the 91A-7320 fork.
 
Hey Pete, if you can't find a 91A ford or complete double-detent top, let me know - I may have a spare fork (not a top), but can't look until the weekend. You have the later gear set (which is good), you just need the correct top or fork.

I prefer the whole top as the double-detent setup is the best of the beasts.
 
JM 35 Sedan said:
Okay, you definitely have the later gears and syncros. I can see why it was not going into 2nd gear based on the position of the collar/sleeve. That's typically one of the reasons why the 68-7320 fork does not work even when the internal dimension of the fork is ground or reshaped to fit the later syncro 2nd/3rd gear collar.
I think your best bet would be find a complete and correct double detent '39 type shifter top with the 91A-7320 fork.
Click to expand...
514967
 
Okay. I have the entire double detent top but I see now that I have the wrong second/high fork. The photo I posted shows the synchro where it winds up when I shift into second. It's about 1/4" shy of contacting the second gear due to the wrong fork. Here are the pictures I wanted to post originally but my Apple / Apple got screwed up.
 

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PeteVS said:
Okay. I have the entire double detent top but I see now that I have the wrong second/high fork. The photo I posted shows the synchro where it winds up when I shift into second. It's about 1/4" shy of contacting the second gear due to the wrong fork. Here are the pictures I wanted to post originally but my Apple / Apple got screwed up.
Click to expand...
514998


514999
 
So, I guess the only question left is, "Did the 68-7230 fork EVER work with the new synchro in days gone by?"
 
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