Noah H.
New member
- Joined
- May 16, 2024
- Messages
- 3
- Tractor
- 1945 Farmall A, 1948 Case VAH, 1946 Perrin
Hello,
I am working on a 1948 Ford 8N that had a bad growl in the transmission. Upon splitting the tractor and inspecting things, I determined that the mainshaft pilot bearing (part number 9N7120) was the bad one. Its outer race is cut into the input shaft drive gear, and it presses onto the transmission mainshaft. It was easy to replace, although not cheap. I also replaced the input shaft bearing (part number 9N7066) to be safe.
The result of this is that the mainshaft bearing preload is incorrect, and attaching the input shaft to the transmission puts an enormous preload on the mainshaft and input shaft bearings. The shims used to set this preload on the mainshaft and input shaft bearings are installed from the back of the transmission, and require splitting the transmission from the differential housing to access. I'd like to have this tractor back together soon, and I could avoid splitting the transmission from the differential if I put the same style shims under the input shaft housing - it would have the same results inside the transmission. Is there any reason I shouldn't shim from the front of the transmission, under the input shaft housing, instead of from the back of the transmission? I did a little looking, and it seems that Sherman transmissions that mount in place of and act as the input shaft do use shims there to set preload. The only problem that occurs to me is that the input shaft would sit slightly further forward than before, meaning that the input shaft gear would mesh with the countershaft gear in a marginally different spot. I don't know enough about the properties of gears to know if this could cause any issues. It helps visualize the transmission to see a parts diagram or Just8N's YouTube video showing the way the transmission goes together.
Thoughts?
Thank you!
Noah H
I am working on a 1948 Ford 8N that had a bad growl in the transmission. Upon splitting the tractor and inspecting things, I determined that the mainshaft pilot bearing (part number 9N7120) was the bad one. Its outer race is cut into the input shaft drive gear, and it presses onto the transmission mainshaft. It was easy to replace, although not cheap. I also replaced the input shaft bearing (part number 9N7066) to be safe.
The result of this is that the mainshaft bearing preload is incorrect, and attaching the input shaft to the transmission puts an enormous preload on the mainshaft and input shaft bearings. The shims used to set this preload on the mainshaft and input shaft bearings are installed from the back of the transmission, and require splitting the transmission from the differential housing to access. I'd like to have this tractor back together soon, and I could avoid splitting the transmission from the differential if I put the same style shims under the input shaft housing - it would have the same results inside the transmission. Is there any reason I shouldn't shim from the front of the transmission, under the input shaft housing, instead of from the back of the transmission? I did a little looking, and it seems that Sherman transmissions that mount in place of and act as the input shaft do use shims there to set preload. The only problem that occurs to me is that the input shaft would sit slightly further forward than before, meaning that the input shaft gear would mesh with the countershaft gear in a marginally different spot. I don't know enough about the properties of gears to know if this could cause any issues. It helps visualize the transmission to see a parts diagram or Just8N's YouTube video showing the way the transmission goes together.
Thoughts?
Thank you!
Noah H
