Final Drive Fluid '48 Cub

Mon Dec 17, 2012 8:43 am

Got around to changing the fluid in the final drives this weekend. Looked at the manual and on FarmallCub.com as well and all said 1 3/4 pints each. That seemed to fill the pan completely, so when reassembling, the inserting of the gear caused it to overflow a bit. Is that the norm or am I missing something. Thx.

Re: Final Drive Fluid '48 Cub

Mon Dec 17, 2012 9:24 am

yes there is a fill plug on the back side of the finial, takes a 1/2 in drive to fit it.

Re: Final Drive Fluid '48 Cub

Mon Dec 17, 2012 9:28 am

That is full capacity, but to get that much in it has to be added via the fill plug just above the pan. The plug is between the drawbar mounting holes and takes a 1/2 inch ratchet or extension to remove and replace it. All that is really needed is enough for the big gear to dip into it a ways, and it then carries it up to the upper gear, so filling the pan to just below the top then bolting it in place is sufficient. That being said, I do go ahead and add enough through the hole to bring it up to that level though, just to be on the safe side.

Re: Final Drive Fluid '48 Cub

Mon Dec 17, 2012 9:37 am

Thx. I missed that little detail, but of course my eyes and my reading comprehension not what they used to be. I'll pull the plugs just to be sure I'm full. Thx. to all.

Re: Final Drive Fluid '48 Cub

Mon Dec 17, 2012 10:39 am

Really, it's a lot less messy if you install the pans dry and then put the fluid in through the level check plug :)

That said is there any way we can stop calling it "fluid" and start calling it oil, or gear oil or gear lube? For some reason calling it fluid evokes mental images of disgusting biologically-based substances.

Re: Final Drive Fluid '48 Cub

Mon Dec 17, 2012 10:50 am

Fill the pans to an inch and a half below the top and carefully install them, using Indian Head sealer on both sides of the gasket. No overflow and no leaks.

Re: Final Drive Fluid '48 Cub

Mon Dec 17, 2012 12:01 pm

I am confident that the factory assembly method was to install the pans dry and then fill through the indicated holes. Correct fluid level with minimum mess.

The finals probably were fully assembled, including the pans, then installed on the tractor, then the lube was installed.

Re: Final Drive Fluid '48 Cub

Mon Dec 17, 2012 12:17 pm

I overfilled mine. Took a couple months to self-correct all over my garage floor.

Re: Final Drive Fluid '48 Cub

Mon Dec 17, 2012 12:52 pm

LOl. Yeah, my garage has a bit of a gear oil smell. Oh well, it would have been this or diesel or gas or paint. One thing I'm learning about the cub, lots of plugs. Thx. to all.

Re: Final Drive Fluid '48 Cub

Mon Dec 17, 2012 1:09 pm

Having said all that was already mentioned, you really only need to keep the gear dipped in gear lube. It's not necessary to "fill" the gear lube till it comes out the fill port. Most folks here will just put in enough like Don mentioned, so that when the pan is installed, the gear lube is not above the gasket. This is quite adequate to keep the gears sufficiently lubed, and there's no chance of the gaskets leaking and dropping oil all over the place. Chances are, you could probably run the things totally dry and there wouldn't be any problems, but it's not worth trying.

Re: Final Drive Fluid '48 Cub

Mon Dec 17, 2012 1:16 pm

gitractorman wrote:Having said all that was already mentioned, you really only need to keep the gear dipped in gear lube. It's not necessary to "fill" the gear lube till it comes out the fill port. Most folks here will just put in enough like Don mentioned, so that when the pan is installed, the gear lube is not above the gasket. This is quite adequate to keep the gears sufficiently lubed, and there's no chance of the gaskets leaking and dropping oil all over the place. Chances are, you could probably run the things totally dry and there wouldn't be any problems, but it's not worth trying.


But it's more fun to laugh at those of us who overfill and have stinky garages.

Re: Final Drive Fluid '48 Cub

Mon Dec 17, 2012 2:02 pm

To play the devil's advocate , If your rear seal was leaking would you drain a quart of oil out of the engine? I think not. If your seals are in good condition it will not leak when filled to the proper level.
If you are not going to work the cub less lube should be OK. I fill mine to the recommended level. I have crossed the fence on this one. I also use to believe only about half enough gear grease was enough. But I found out different.
Boss

Re: Final Drive Fluid '48 Cub

Mon Dec 17, 2012 3:20 pm

Bus Driver wrote:I am confident that the factory assembly method was to install the pans dry and then fill through the indicated holes. Correct fluid level with minimum mess.

The finals probably were fully assembled, including the pans, then installed on the tractor, then the lube was installed.

Always an interesting question how the factory did things, answers are often a surprise. My guess is that they put in a measured amount and didn't check with the level plug. Also, given the inconvenience of working under the tractor to fill them, I wouldn't be surprised if either:
A. The nearly assembled final drive was inverted, a maesured amount of oil dumped in the open bottom, pan was bolted on and it was then turned upright.
B. A fully assembled final drive was turned on it's side, a measured amount of oil was poured in the filler/level plug and it was turned upright.

The only evidence I have to support the blind addition of a fixed amount is a bulletin from early in the production cycle of the Farmall A. In essence, it said we need to reduce the published volume for the transmission from X to Y. It has been discovered that we have been overfilling them at the factory.

A marginally related story: I bought a new '77 Jeep. When it was a year old, I took it in for lube and inspection. When the guy pulled the filler/level plug on the front axle, oil came pouring out. No way that much could have been put in unless the axle was laying on it's back. At least as much had to be added to the rear differential to bring it up to the plug. It had about the right amount oil, just in the wrong places.

Re: Final Drive Fluid '48 Cub

Mon Dec 17, 2012 8:24 pm

Luckily the later editions of the Operator's Manuals switched to HyTran from gear oil. Really don't like the smell of gear oil.

Finals are pretty well known for leaking. I have found Hylomar is a good gasket sealer, doesn't harden and can be 'reused'.

Re: Final Drive Fluid '48 Cub

Tue Dec 18, 2012 11:59 am

You guys make me smile..... :) :)

I would not want to fill the finals in the factory unless they were fully assembled. Since there are seals at all openings, they most likely fully assembled them, injected the measured oil into the fill plug and capped it off. Just my 3 cents worth from being in the transmission business.

As far as oil in the finals - yep only takes a few ounces of oil to lube the gears and bearings, but in my experience, a final drive that's not leaking has no oil in it......so fill er up with the right amount and when she stops leaking, fill her up again.....