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New member with a question about Sherman transmission unit.

798 Views 13 Replies 4 Participants Last post by  Nouveau Redneck
Hi all, new member here with my first 'real' post.
I'm working on a "N" series Ford that has been in my family for about 45-50 years. My Dad always referred to it as a 9N, but I'm not sure, based on the stamped serial #.
It started leaking a lot of trans oil from the two 'jiggle' pins and affecting the clutch. I noticed a couple drips about 6 months ago and knew that I was going to have to split the tractor to fix it.
It got really bad last week and it seemed that it was much worse very quickly.

I split the tractor and was thinking that the input seal for the transmission was bad.
The tractor has a Sherman unit, and from what I've read here it is the combo unit with the lever through the side of the bell. There was a LOT of oil inside the housing so I could not pinpoint or positively identify the source of the leak. I pulled the input off of the Sherman expecting to find a torn seal but the seal was snug and was in great shape.
All of the mounting bolts for the Sherman were tight, the mounting adapter was tight (not cracked) and none of the gaskets or shims appear to be the cause.
What I DID find was a 3/8" hole in the top cover of the Sherman unit.

This tractor has never been apart since we've owned it so I don't know if that hole was leaking a little oil over a lot of years? I looked all over for a 3/8" cup plug but there was nothing in the bottom of the housing, no plug in the sump of the Sherman, no 'fuzz' stuck to the magnetic plug of the Sherman to indicate a plug got ground up.
It seems odd to me that this hole has been there 'forever' and it only recently started leaking...?

So, all this information to ask for opinions/advice....
I can install a 3/8 cup plug in the hole -or- I was thinking that I might tap the hole for 1/8 npt and install a 45* street elbow with a 1/8 npt axle vent if folks more familiar with these tractors think it might be wise. I have researched a few of these Ford N forums to see if I could find a picture of a Sherman top cover and almost all of the pics I could find showed no hole, no breather, no threaded plug. There was 1 picture (very low res) on ebay that showed what looked like a threaded plug but I couldn't be sure.
I'm attaching a picture to show the hole and it's location, I can't imagine how this has been open for all these years and only recently started pushing oil....but the indications are that trans oil has been contained everywhere else that I looked.

Any and all opinions welcome! Thanks in advance!
I do not do any of this internet stuff on my phone, normally all of this kind of stuff takes place at the end of the day from my home computer so my replies will not be immediate.
Let me see if I can post the pic...

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Thanks, I'll post a pic of the VIN stamping but it is pretty beat-up.
Visually, the tractor looks exactly like the one shown in the thread "New to me 1941 Ford 9N" started by "smalljob". All except for the nice restoration on his, of course.
Ours is pretty rough. We do have two 8N tractors and this one is quite a bit different: front distributor, right side generator with 1 wire, no door for the air cleaner, no running boards, steering gear configuration, and misc stuff like that. It is possible that it was painted red over the gray at some point in it's life.
I have been crash-coursing about these tractors and specifically the Sherman transmission for the last few days to try and get familiar with them in order to make logical choices about repairs and parts.
Here is the best shot I could get of the stamping on the block:

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Thank you, I read that last night and everything about our's but the block stamping says its a 9N. It looks to me as if the stamping starts with "8N".
Maybe it got a different engine before we got it? Could be, a lot of years have passed since it was new.
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That hole on the Sherman is for a vent plug to allow things to heat up when the tractor is being used and cool down afterwards without air pressure building inside, as that might cause a seal to leak. Do not close it off completely. Get a replacement vent plug and install it. The part number is 01A7034 and it is still available. You should be able to get one from any New Holland dealer.
Thank you for that information, I was thinking that a vent would be the most logical reason for that hole.
Much appreciated!
Just to wrap up this subject I thought I would post a pic of the repair. I went with my original thought about a vent, the New Holland breather looked to be a bit 'spendy' just from a quick internet search.
Used a Weatherhead 45* street el and a Dorman axle vent. Easy to do and much less $$. I'll reseal and re-gasket the Sherman and begin reassembly 'soon'.
Thanks for the help and suggestions!

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Once the vent is fully tightened it is only about 1/4" above the top cover.
I mocked it up with line-up studs and there is plenty of clearance.

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