Adding grease to the U-joint?

Adam/Mill Valley CA

Adam/Mill Valley CA

Senior Member
I was doing a routine lube service on my '36 yesterday, and as I usually do I put a few pumps of Cornhead Grease in the U-joint cavity through the Zerk fitting-but realized I really don't know if that's appropriate or not. When I rebuilt the transmission years ago I put on a new U-joint and filled the cavity about 1/2 full with JDCG. There's no external leak, although I suppose a small amount could migrate forward to the transmission-but I can't see where any significant amount would be lost. What do others do concerning this?

Adam
 
So to be clear, at routine servicing you fill up the U-joint chamber each time? Where does the grease go, forward to the ****** or back to the torque tube? Is that a problem?
 
There is no seal between the back of the transmission and the u joint. The transmission oil lubes the u joint. The zerk lubes the clamshell parts.
 
It takes one pint .when empty I would use modern CV joint lube, or make a mix of 3to one grease and oil it can work its way back to the Dif , I have read a article in a hand book for the British v8 pilot that describes a mixture including tallow ,it will end up Gear box oil and grease mix in time .
 
Not exactly apples to apples but similar setup.

On my '30 Model A, I followed the recommendations touted by some on a Model A forum. That is, remove the speedometer gear housing and pump the clamshell fitting with grease until you can see grease oozing from the speedo gear opening on the torque tube.

Well I did just that and the next time I checked the transmission, it was full of red grease that I had used to fill the clamshell and u-joint housing. :(

Never did figure out where the transmission oil went. Differential level was the same and no oil leaks were seen.:confused:

Needless to say, that was the last time I pumped grease into the clamshell housing like that. I went to just a couple of pumps a year after that.
 
Any of you ever used a seal on the backside of the rear trans bearing? Then the migration of the lube back/forth wouldn’t happen and you could be assured the U joint would be lubed with whatever you are putting in there.
 
alchemy said:
Any of you ever used a seal on the backside of the rear trans bearing? Then the migration of the lube back/forth wouldn’t happen and you could be ***ured the U joint would be lubed with whatever you are putting in there.
Click to expand...

I used a sealed bearing in that position when I went through the transmission for my '40. Pulled the seal off of the front side of the bearing to ensure that it was lubricated by gear oil and left the seal on the backside. Has worked well for the last 6 years...
 
As stated above The U joint is lubricated with transmision oil. Not grease. The zerk if it has one is for the clam shell. The oil goes all the way to the driveshaft seal aft of the speedo gear. I'm not shure why anyone would want to turn their transmision lube into a nasty goop that doesn't flow as it should. All Ford and GM torqu tube U joints were lubed this way . We do use grease as an assembly lube but thats all. Ive been driving this type of Ujoint for 50 plus years and hundreds of thousands of miles and never greased one after assembly. Tim
 
OK, so now I'm thoroughly confused. Is packing the U-joint cavity with low melting point grease (e.g. John Deere Cornhead Grease) just an initial assembly maneuver, and subsequent lubrication of the U-joint is left to migration of transmission oil backwards? If so, how do those who use a sealed rear trans bearing (with the forward seal removed) expect the U-joint to survive? Anyone? Also, I seem to recall when I last rebuilt my transmission that there's a hole in the inner part of the clamshell that would allow grease from the Zerk to migrate to the inner cavity-or am I misremembering things?
 
The hole on the inner cone is covered by the torque tube bell. So any lube put in the zerk has a very convoluted route to get into that hole.

What did Rumbleseat say about this issue?
 
pistonbroke said:
As stated above The U joint is lubricated with transmision oil. Not grease. The zerk if it has one is for the clam shell. The oil goes all the way to the driveshaft seal aft of the speedo gear. I'm not shure why anyone would want to turn their transmision lube into a nasty goop that doesn't flow as it should. All Ford and GM torqu tube U joints were lubed this way . We do use grease as an assembly lube but thats all. Ive been driving this type of Ujoint for 50 plus years and hundreds of thousands of miles and never greased one after assembly. Tim
Click to expand...

That's not correct at all. If you have oil going through the trans output shaft, you've overfilled it. You can put sealed bearings in there now, but originally they had a slinger to keep the oil in the trans.

Originally ford used a soda soap, which is best described as an oil with grease like characteristics. Think of it like a thick bacon grease, it turns to liquid when hot and solidifies when it's cold. It's not just thicker like a 600w oil or STP.You use the zerk fitting to inject it.
 
Hitman said:
If you have oil going through the trans output shaft, you've overfilled it. You can put sealed bearings in there now, but originally they had a slinger to keep the oil in the trans.

Originally ford used a soda soap, which is best described as an oil with grease like characteristics. Think of it like a thick bacon grease, it turns to liquid when hot and solidifies when it's cold. It's not just thicker like a 600w oil or STP.You use the zerk fitting to inject it.
Click to expand...

This is correct!
 
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