1939 transmission questions

R

Rusty30roadster

Senior Member
Hi, I’m going to be putting a 39 transmission into my A. When looking into the transmission, how can I identify if it needs to be torn down and gone through? The gears look really good inside but today a small retaining clip maybe fell free??. Again, the inside looks good… I think…. but I do not know if a tear down is needed - how do you tell?

If this needs to be torn apart, where is the definitive source for instructions on how to do this? I’ve read the 35ford page but in the absence of detailed pictures, it doesn’t make sense to me. Any one have a different resource for the detail I need to do this the first time?

Thanks J
 

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Rusty30roadster said:
Hi, I’m going to be putting a 39 transmission into my A. When looking into the transmission, how can I identify if it needs to be torn down and gone through? The gears look really good inside but today a small retaining clip maybe fell free??. Again, the inside looks good… I think…. but I do not know if a tear down is needed - how do you tell?

If this needs to be torn apart, where is the definitive source for instructions on how to do this? I’ve read the 35ford page but in the absence of detailed pictures, it doesn’t make sense to me. Any one have a different resource for the detail I need to do this the first time?

Thanks J
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Get Mac Van Pelts book on transmission overhaul.
Bill
 
It looks like the spring retainer that hold the shoes in place in the synchronizer has come loose. I do not know if you can get it back where it needs to be but that will have to be done. Other than that, it actually looks good.

My opinion,

Chris W.
 
That’s a late synchro top loader transmission. Inspecting the cluster gear shaft is critical. Low and reverse gear are not synchronized, and suffer from gear clash. Examine the shift tower.Late towers are dual detent shift rai design, replace the springs and balls. The ball on the end of the shift lever also is a heavy wear point.you have to disassemble to put the synchro back together. Sliding the blocker ring back pops the shoes out .. synchronizer has to be complete to assemble.

X3 on Van Pelts book, the gear charts are crucial.
 

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Actually, the very first of the new type 91A synchronizer assemblies had the three detent plates and the two spring rings to hold tension on those plates. They were later discontinued for the early type plates with detent balls and coil springs. They returned in 1949 in the 8M prefix synchonizer for the Mercury cars that obsoleted the early style synchonizer. I've not had a problem with those spring rings coming out of the hub. Once they are installed in the hub, they usually stay put unless the ring has been bent out of it's original shape. The blocker rings will keep them from being able to come out

The transmission in the photos looks to have decent gears in it. The blocker rings look like they are going pretty deep into the gear. There is likely a lot of wear on the taper faces. Since the main shaft is sort of hanging out the back all the parts on there are out of normal position.

The cases are vulnerable to excessive wear on the thrust surfaces of the counter shaft cluster. The case can crack between the front counter shaft bore and the input bearing bore. The trans in question doesn't look too bad with what is visible in the photos but careful inspection of all parts will clear or break it's bill of health.
 
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It's kinda hard to tell in the picture but the reverse idler looks a little rough.
 
Van Pelts book is excellent and his advice over the phone is also good.
There is a lot to check to get one of these perfect but its all in the book.

Another good source is Al Zannino in Hemet California from Al's Transmission Mechanix.
(ATM)
 
That clip sits inside a "lip" of the three synchro blocks. You might be able to get it back in using a small flat blade screw drive as you turn the input shaft. If not, it's got to come apart to reinstall.

If it was mine, I'd tear it down and check it over unless you know it was rebuilt right.

It is a real pain to take a trans out once it's installed in a car. Either the motor or the rear needs to come out depending of the center crossmember.

Follow Mac's book to the letter. Don't skimp or skip steps. Only way to check back lash is with a rear bearing retainer bolted in place.

Go as tight to the spec as possible. Too loose, it will eventually start popping out of 2nd and the cluster wants to thrust upward.

Mac makes shims to help get the clearances where they need to be.

Do it once and do it right while it's out of the car.

Good luck and report back.
 
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