Transmission 2nd Gear Condition Question

[19Fordy]

I am trying to determine if the second gears I have in my 40 Ford transmission are in good condition. I found Mr. Van Pelt's book to be an excellent reference but, I am quickly learning that expert "Transmission knowledge" required is much more than what's written down. The more I read his book, the more I realize the vast amount of knowledge he posses that can't be written down.

The first photo below shows a used 40 Ford transmission main shaft with 2nd gear (on the right) and a NOS Ford 2nd gear (on the left) butted up against it so as to compare the two sets of synchronizer teeth that are cast as part of the 2nd gears.

The second photo shows a close up of the same NOS 2nd gear (on the left) and the same used 2nd gear still attached to the main shaft (on the right).

I would like to know if the synchronizer teeth of the used 2nd gear (on the right) are in good condition and good enough to be reused. Do they have to look like the teeth show on the 2nd gear shown the last 2 photos to be usable? I would assume there is a certain amount of wear that is acceptable.

I am trying to learn how to determine what used parts are good enough to be reused" in a transmission rebuild. I appreciate what knowledge is "stuffed" into Fordbarner heads.

I do have some NOS and used transmission parts that I would like to sell but, do not want to mislead anyone. THANK YOU. JIM

[Mart]

The gears you are showing are early type synchro. See the narrower band of taper? See the bigger gap between the teeth and the gear teeth?
Early synchro.
See the synchro teeth on the end of the input shaft?
Wide taper. Narrow gap.
You need a 2nd gear that has the wide taper and narrow gap, same as the input shaft.

Mart.

[19Fordy]

Mart, I am having trouble discerning what you mean by "narrow gap".

Have the sides of the teeth in the right hand side been worn thinner? Not usable?

[Will D]

I believe this is the narrow gap Mart is referencing below on right. You would need another 2nd gear that has same length taper which would only leave room for the "narrow gap"

Wide gap on left, narrow gap on right in photo.

[19Fordy]

Will D and Mart: Thank you for that info. I can see now that it's easy to mismatch parts.

Perhaps, I am asking my question the wrong way.

Pictures below show the entire main shaft 2nd gear assembly as I removed it from the transmission. The flakey stuff is white nail polish I used to mark the tooth.
QUESTION: Are the gear teeth and synchronizer teeth in good usable condition -good enough to use so I don't have to buy new 2nd gear?

THANKS again. Jim

[Will D]

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Sry Jim, I don't have the expertise to comment on acceptable wear. Hopefully Mart will pop back or someone else with more than my 2 cents

[19Fordy]

ok. Thanks for reply anyhow.

[Andy]

You are showing the synchroniza and not the second gear. I think I have a good one if you need it. Post more pics.

[bbrocksr]

Originally Posted by Will D

I believe this is the narrow gap Mart is referencing below on right. You would need another 2nd gear that has same length taper which would only leave room for the "narrow gap"

Wide gap on left, narrow gap on right in photo.

The gap between the syncro teeth and the main teeth.

Bill

[Will D]

...

[Mart]

Jim, In this photo:

Red arrows show the narrow and wide gaps between the synchro teeth and the gear teeth.
Green arrows show the corresponding narrow and wide synchro cones. (missed the head of the lh side of the rh green arrow)
Early synchros: wide gap, narrow cone.
Later (your) synchros: narrow gap, wide cone.

The blue arrows and shaded in areas show undesirable wear. Note: The blue arrow pointing to the left might not be wear, it could be a trick of the light

Your input shaft gear synchro teeth show a lot of wear.
While it would "get you out of the desert" it in not suitable for putting into a gearbox that you want to call rebuilt or even just called a good runner.



Mart.

[Mac VP]

The answers you’ve been given above are correct. Mart’s observation about the wear on the synchro teeth is correct. You can see that almost half of the width of the synchro teeth is worn away. This would be a very sloppy fit in the internal splines of the synchro sleeve.

Sometimes the aftermarket gear manufacturers would make subtle modifications in how they made a gear. Functionally, it would interchange with an original but you’d see a visible difference. In this case I think the visual details mean a bit more.

I don’t think I saw the inside bore of the gear that has the shorter tapered cone, but if it was smooth and rode on a separate bronze bushing, that would confirm that you have the earlier 32-38) type second gear......those can not be used with the late style synchronizer.

A picture of the inside front edge of the suspect gear would confirm if it’s the early or late style.

[Terry,OH]

I would not use the input shaft since the syncro teeth are too worn width wise. Another point is often you will see what appears as damage on the syncro teeth. Carefully look at the main gear teeth angle and you can see the damage is from when the main teeth are cut into the gear. The cutter nicks the syncro teeth. Syncro teeth with these minor cuts are OK. Check the leading edge of the teeth of the syncro outer sleeve. They are associated with the damage on the input shaft and the sleeve may also need replacement. It appears the sleeve has damage and is wearing the syncro inner hub, from the appearance of the inner hub, in one of your photos.

[19Fordy]

Again, thank YOU ALL for taking the time and effort to post pictures and related info. that
"tells the true story". Looks like my gear is "toast". I have learned a lot from you. Thanks again. Jim

[JM 35 Sedan]

Originally Posted by Mart

Jim, In this photo:

Red arrows show the narrow and wide gaps between the synchro teeth and the gear teeth.
Green arrows show the corresponding narrow and wide synchro cones. (missed the head of the lh side of the rh green arrow)
Early synchros: wide gap, narrow cone.
Later (your) synchros: narrow gap, wide cone.

The blue arrows and shaded in areas show undesirable wear. Note: The blue arrow pointing to the left might not be wear, it could be a trick of the light

Your input shaft gear synchro teeth show a lot of wear.
While it would "get you out of the desert" it in not suitable for putting into a gearbox that you want to call rebuilt or even just called a good runner.



Mart.

Mart, good analysis and illustration with your different colored arrows. All your comments are well stated and right to the point.

[Bored&Stroked]

If the second gear has a fixed bronze bushing in it, then it was intended for a later transmission and should be okay as far as being a correct part. As others have noted, there is unacceptable wear on the synchro teeth of the main input gear/shaft.

Keep in mind, those little teeth are the ONLY things that connect the engine to the driveshaft in high gear - and they are about 1/2 worn off. Actually, I've never seen one that worn.

[19Fordy]

B&S: Thank you for adding your thoughts. I am learning lots.