Black gear Oil?

[happy024]

Yesterday I changed the my differential gear lube front and rear in my 95 YJ. The front D30 oil looked ok mainly a grey color. But the rear D35 was BLACK and there was a black film built up on the inside of the cover. Not very thick maybe paper thin. I also noticed the spider gears that sit verticaly some of the gears are looking a little baby swiss cheese like. Little indents on about a quarter of the gears. And the gears that go horizonaly the edges are feathering a little. The rod that conects the 2 horivonal gears is a little sloppy in there.
I am planning on regearing after I get moved to Ohio. So I guess my questions are-

What is the black from?
What can I do in the future to keep this from happening again?
Can I tighten the rod inside the spider gears?
And any other coments or help would be great.

 

[redrooster]

The gray color in the front means that you hvae a little water in there. The black sounds like it is just ancient and burned.
There should be no slop in the pin and no you can't tighten it. It taps in with a hammer and is secured with a roll pin. Is the slop in the spiders or where the pin goes int he carrier? You may have lost the roll pin.
Ditch the spiders and install a locker if the pin is still any good.

 

[happy024]

The spider has a little play to it too but very little.
I am going to regear to 4.88 and put lockers in this coming summer.
But will I be fine for the time being?
This is my everyday driver till I find a cheapo car to go back and forth to work in.

 

[redrooster]

Hard to say. It may run for years or let go tomorrow. Start saving up for new gears.

 

[west747]

your best best( as long as your ring and pinon are still good) to save the rear end is to get a lunch box locker and get rid of the carrier gear and clean the case out really good..

 

[happy024]

What do you use to clean out the carrier?
And this might seem like a stupid question but what would be considered a lunch box locker. I've seen that term used a couple of other times.

 

[west747]

i juest used paper towels and sopped it up..but you could also use brake cleaner...a lunchbox locker is a locker that replace the carrier gears and fits inside the carrier

 

[redrooster]

Loc Rite or other similar design where you don't replace the carrier are considered "lunch box" lockers. Detroits and other similar units replace the whole carrier and require that the gears be set up again. Basically what I was saying in post #2. Chunk the spiders and install a Loc-Rite.
Clean the inside with a can of the cheapest Autozone Carb or Brake Cleaner you can get. Try to wash the crud away from the open bearings. Use a pan to catch the mess.

 

[happy024]

Thanks everyone. the Loc Rites or similar as red said is what i was assuming but we all know what happens when you start to assume things.