Looking For Worm Gear

https://www.lionelsupport.com/...TOR-W-GEAR-FT-DIESEL

Pitch and length looks about right.

Again, a search tip, what I do when I run into your situation at both Lionel and MTH, I take the part name and then search for that and then compare the resulting photos trying to find a match.

Again, from the product page for your engine you chose this part

But then I just take the part name- DC MOTOR / W/GEAR / FT DIESEL and search for that instead

https://www.lionelsupport.com/...AR%20/%20FT%20DIESEL

This is the one I ordered and the pitch does not match.

Vernon's second link yields a ton of options. To help sort out options,  I have tried the Lionel email with reasonable success: talktous@lionel.com

https://www.lionelsupport.com/...AR%20/%20FT%20DIESEL

@dennish posted:

This is the one I ordered and the pitch does not match.

Right, I got that in the first post and then, gave you an alternate part number with picture......

https://www.lionelsupport.com/...TOR-W-GEAR-FT-DIESEL

part 6804720100 VS 6808154100

If I combine the 2 pictures- your failed one top half, and the one linked above bottom half....

Nicely done!  Thank you!

Dennis, as I remember that loco is from the era when Lionel first switched from Pullmor to can motors.

For years going back to the 1940s, Lionel had used a triple-start worm on the big, slow-turning Pullmor motor, yielding a ratio of about 8 to 1.  To get more torque out of the smaller motors in the FTs, they substituted a two-start worm yielding a ratio of about 12 to 1.  (I think they also used this worm in the FM H-12-44 switchers.)  The problem was that on the FTs at least, the mesh wasn't exactly right.

I remember reading that service centers, or perhaps even the Lionel factory, were putting pieces of cardboard(!) between the motor mount and the truck block in an attempt to correct the mesh.  Your post is not the first about these double-start worms failing in service.  At least one other Forumite ended up replacing his motor and the truck block with a traditional triple-start worm and compatible 25-tooth worm wheel.  If you do this, the loco will run faster. But at least it will run.

If the motor recommended by Vernon proves to be a match, pay careful attention to the gear mesh for best operation and longevity.  My $.02.

@Vernon Barry posted:

Right, I got that in the first post and then, gave you an alternate part number with picture......

https://www.lionelsupport.com/...TOR-W-GEAR-FT-DIESEL

part 6804720100 VS 6808154100

If I combine the 2 pictures- your failed one top half, and the one linked above bottom half....

I have to say, pretty clever method of matching the gears!

@gunrunnerjohn posted:

I have to say, pretty clever method of matching the gears!

I have a device we use in clock repair that will give correct pitch tooth count and such. It was a hand me down made by the Ansonia Clock Company. Let me do some research to see if anyone else makes or made this thing.

@ThatGuy posted:

I have a device we use in clock repair that will give correct pitch tooth count and such. It was a hand me down made by the Ansonia Clock Company. Let me do some research to see if anyone else makes or made this thing.

That would certainly be useful, but you do have to have the gear in hand to do those measurements, Vernon did them by photo.

@gunrunnerjohn posted:

That would certainly be useful, but you do have to have the gear in hand to do those measurements, Vernon did them by photo.

Very true. The only issue I see with the photo match is if you do not know the scale of the original photo it could south fast. That said we need to work with what we have and his “fix” works for me.

I'm kind of laughing because it was done with MS paint. As low tech and just above zero effort. Crop and copy/paste. It was shear luck both pictures were horizontal, and even with the different angle of view and obviously scale, somehow it lines up.

I probably could not do that again if I tried for hours with different pictures of a different motor.

@ThatGuy posted:

Very true. The only issue I see with the photo match is if you do not know the scale of the original photo it could south fast. That said we need to work with what we have and his “fix” works for me.

I did think of that, I guess we'll know when the new motor is tested.

@gunrunnerjohn posted:

I did think of that, I guess we'll know when the new motor is tested.

It would take Lionel all of about 5 min to post full specs on the motor and gear…..then again lol

@ThatGuy posted:

It would take Lionel all of about 5 min to post full specs on the motor and gear…..then again lol

Why make it easy to fix the old stuff?