Farmall Cub Transmission

R

RunningRed

Well-known member
Hey fellas while I wait for my new tacometer to show up I figured I would get started working on replacing the transmission cover and rear cover gaskets by the pto. I drained the 85-90wt I put in last year out and there was a bunch of metal flakes in it. I flushed out the transmission with kerosene last year before filling it. I don't know why there was so much flakes unless it was mixed in with the black sludge in the rear differential since both are connected. Could have been the gears still grinding after changing the clutch and pilot bearing last year. It doesn't grind in the winter only in the summer so next time I will be using 85-140wt. Also when I was looking into the transmission I noticed the 2 lower gears arent engaging on a few teeth and appear to be pitted. The rest of the teeth on both gear look good. I finished inspecting all of the gears and non are missing teeth and nothing appears to need replacing luckily cause I don't want to do a rear split this year. Next year I plan on going through the transmission. There looks like a lot of thick black sludge inside the top of the differential and I'm not sure but on the sides there appears to be oil galleries running down the sides to each axle bearing on the left and right but I see little holes I circled and there facing the back of the tractor not up to receive the oil.

What is a good way to clean all of the metal flakes and chips out? How can I clean out all of the black sludge with out making one heck of a mess? Any ideas how to check the the bearings in the transmission to see if there bad?1000002356.jpg1000002355.jpg1000002354.jpg1000002352.jpg
 
I don't think you would hurt anything to pressure wash the inside of the transmission. There are some channels that transfer the oil to the front and rear bearings that need to be clear otherwise the bearings won't get the needed lubrication. Not sure what you mean by the rear differential, if you're referring to the pto, yes it's a common fluid for both and could have have some unwanted stuff settled in the bottom of it. JMHO Stan
 
staninlowerAL said:
I don't think you would hurt anything to pressure wash the inside of the transmission. There are some channels that transfer the oil to the front and rear bearings that need to be clear otherwise the bearings won't get the needed lubrication. Not sure what you mean by the rear differential, if you're referring to the pto, yes it's a common fluid for both and could have have some unwanted stuff settled in the bottom of it. JMHO Stan
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I was trying to think how to clear those little weep holes that funnel oil to the bearing. I was tossing the idea of shooting some high pressure air through them. I don't know about pressure washing, I think that would make a mess. Pto, that's what I meant not differential I got my words screwed up.
 
the rust pits in the gears , it had water in the unit for a long time sitting it looks like, you can fill it with kerosene and drive it around, enough lube in the kero for the bearings
 
tst said:
the rust pits in the gears , it had water in the unit for a long time sitting it looks like, you can fill it with kerosene and drive it around, enough lube in the kero for the bearings
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That's what I was thinking but it's only a few teeth on the 2 bottom gears. Why aren't those teeth that are pitted making worn shiny like the rest?
 
If you use the pressure washer, after using it, I would blow out all you can get to with air, to dry it. Use the air in the bearings you can reach too. Use your safety goggles when using the washer or the air.
 
1000002362.jpgI got it all flushed out and scrubbed with kerosene. I prob got 99% of the black sludge cleaned out. Put new gaskets on the pto cover and shifter handle cover. I also have 75-140wt oil on order and should be here Monday.
 
Just a reminder...it only takes about 3-1/2 PINTS of gear oil.
The "full level" plug is on the lower left side of the transmission toward the rear.
Remove that plug (easiest with a pipe plug socket!) and while filling, when gear oil starts coming out the plug hole, it is "full".
 
The housing looks good in your picture.
While you have it apart, you could look at the PTO pilot bushing, it is in the rear end of the long clutch shaft.
The front of the PTO shaft sticks into it. The bushing can wear out, and be mostly gone.
Below is a listing for it at TM Tractor Parts, you can look at the pictures.
http://www.tmtractor.com/new/pt/752fp.htm

The surface on the PTO shaft where the bushing runs should be smooth.
There is a How To in the How To section about removing the bushing. I think he used a bolt and turned it into the bushing.
Below is a picture from TM Tractor Parts of the bushing in the shaft. :)
I sent you a message.
 

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Well I got the gear oil into the transmission today. I had purchased 75wt-140. I have to say that this full synthetic 75-140 isn't nearly as thick as the 85-140 conventional gear oil I have. I was using 85wt-90 all last year and over winter and was having grinding issues during summer not hardly any in the winter. Seems like the 75-140 has helped a lot with the grinding issues, almost eliminated it completely.
 
If the transmission input shaft is dragging on the CS pilot bushing it will cause the transmission gears to "creep" when there is not enough resistance to keep them from turning. JMHO Stan
 
tst said:
GRINDING IS MORE DUE TO CLUTCH ISSUES
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I put a new clutch in, throw out bearing and pilot bearing. Replaced all the bits and pieces in there also. I reamed the pilot bearing as well for clearance. The clutch is adjusted properly and the free play in the pedal is set to 1". I even engaged the pto and attached a drill to run in the bearing for about 2 hours. I think the issue is more of a slight bow in the shaft running back to the transmission. If not then I don't know cause I tried everything.
 
while its running lay under the tractor look up through the inspection hole and reach up and oull the clutch down, does the imput shaft stop turning ?
 
tst said:
while its running lay under the tractor look up through the inspection hole and reach up and oull the clutch down, does the imput shaft stop turning ?
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Ok, so I went and check it. When craw under the tractor with it off and strap the clutch pedal down I can reach up in there and turn the clutch disk very easily to whole way around with no apparent binding, it turns very effortlessly. However, when I turn the tractor on and press the pedal it slows down but doesn't stop. Now if I get up on the tractor and engage the pto and push the clutch it stops right away.
 
seems to me like you've got a little something still grabbing. As Stan said the transmission input shaft could dragging on the pilot bushing. Or maybe the clutch is so fresh it hasn't had time to wear down a little? I've heard of fresh replacements needing a little bit of time to "break in" and even out any high spots.

The oil has added a little more resistance for it to slip a little (thus slowing the input gears down enough and adding "liquid cushion" enough where they're more like to slip in place without tapping/grinding). This might also explain why this issue went away in the winter (colder weather = thicker oil). And then the added resistance of the PTO being engaged is enough to cause it to fully overcome whatever slight grabbing force is still being exerted on the shaft.
 
tst said:
try and spray some lube through a hole in the clutch disc into the end of the pilot bushing to see if it helps,
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I did some more inspection and I had a helper spin the pto shaft and my input shaft appears to have a slight bend to it. Its not much, I'd say about 0.040. So it's probably just something I'll have to live with until I do a rear split next year to replace gaskets and seals in the transmission.
 
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