Rear End Grease, how much, what type?

ArtGill · November 19, 2011, 05:46:10 PM

I have a NJT Model 20 and while doing a brake job on the rear, the axle was pulled. They was discovered a gray, light grease type substance on the seal and in the axle tube. We haven't pulled the other axle yet, so we are not sure if its local or in the rear end.

My rear end is driven from the front. And the drive line from the transmission is going over the top of the rear end. Is the gear box that takes the shaft from the transmission to the front of the rear end called a "dropbox"?

When we replace the grease in the rear end, what grease does it use and how much? Is the "dropbox" a separate oil/grease system?

I hope all this makes sense.

Thanks in advance. Art

luvrbus · November 19, 2011, 05:56:50 PM

Drop box is what it is called the drop box and differential both are lubed together buy a 5 gal can you will only have a couple of quarts extra use that to change the oil in the boogies and front hubs Hypoid 85/90 or synthetic if you can afford it

good luck

ArtGill · November 19, 2011, 05:58:42 PM

90W gear oil??

Art

TomC · November 19, 2011, 10:33:08 PM

Usually when the oil turns grayish it means it has water in it. You should thoroughly empty and rinse it out, then re fill with 80W/90 gear oil. If you live in hot climate and do desert driving the heavier weight 80W/140 could be used. Synthetic will cut down on friction, but is expensive. If all seals and bearings are in good shape, synthetic would be advised. Good Luck, TomC

TomC · November 19, 2011, 10:36:17 PM

When you refill the rear end, fill it until the oil is even with the fill plug. Go drive it a few miles and then check again. NEVER use a finger in the hole down as being alright. Not only does the oil lubricate, but cools too. If the oil is lower then the fill hole, it will run hotter.

Checking to make sure the oil is even with the fill tube is very important with manual transmissions. Having the oil a finger down, can starve the gears for oil making for premature failure-have seen many transmissions that way. Good Luck, TomC

luvrbus · November 20, 2011, 06:14:07 AM

Art, remove the plug at the drop box pump oil in from the plug on back of the differential case when the oil come out of the drop box plug it will be full and if you have plugs in the hubs pour about a cup in each one,fwiw that is going to be a tough fill job with out a pump it is going to take you awhile
Check on top (driver side) of the axle housing to be sure the vents are not gone when you find a hole with nothing in it the vent is missing allowing water to enter the housing

good luck

ArtGill · November 21, 2011, 05:02:47 PM

Thank you all the information. I've printed this thread to give to my mechanic. Again thanks.

Art