How are the front birfield/axle lubed?

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I just got off of nightshift so I'll try to make sense. I just changed all the fluids in my '78 FJ40. It's my understanding that there are seals in the differential. So what fluid lubes the birfield/axle? There must be something because I have some seepage around the trunion felt. There is also a fill plug above each trunion. ( I assume that's what they are). So what lube is added,how much and how do you drain/check it. Stupid question? ???
 
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There are no stupid questions, only stupid answers. Here's my stupid answer:

Gear oil keeps the ring and pinion lubed. The entire axle housing is filled with this. Where the housing stops, and the knuckle begins (where the Birfield is located), there are axle seals that prevent the oil from leaking into the knuckle. The knuckle and wheel bearings are filled with grease. Usually these seals leak oil into the grease and you get that slimy mess on the outside of the felt.

To empty the knuckles, you need to disassemble the whole thing and pull out all the old grease and replace the axle seals. This is a messy job, but not too difficult. See Morgan's webpage for more info on this. Even if it doesn't need a rebuild, the manual recommends squirting some grease into those fill plugs every once-in-a-while. I believe you should use moly-fortified grease in the knuckles.
 
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Check your front diff fluid as well, most often if there has been oil seepage into the knuckle, there is grease in the gear oil, and often you can tell the extent of oil-grease transfer by how much grease is in your gear oil.
 
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The knuckles are supposed to be lubed as often as the rest of the chassis, BTW. It's not clear to me how much grease is supposed to be pumped in there. Guess it's to overflow. When I got my 89FJ62 recently, I pumped alot of grease into both sides without seeing any signs of overflow. Gear oil leaking into the knuckles is nothing to ignore. I had that problem on my '85 4runner and the oil eventually found its way onto the brakes.
 
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Factory specs call for lithium grease. I got a needle attachment for my grease gun and pumped them all but full. You need to leave room for expansion when everything heats up. The lithium grease is more water resistant. :)
Ed Long
 

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