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Thread: Replacing the oil seals in the front axle cj3b

  1. #1

    Replacing the oil seals in the front axle cj3b

    So if I'm reading the book correctly the oil seals for the front axle on my cj3b it's a Dana 25, they are located inboard of the axle tubes near the third member. They have to be replaced after pulling the third member I assume? Never did anything like that can you walk me through it? I'm sure there's some shims that have to be taken care of if I don't change anything else but the seals can I just pop the third member out, change the seals, and replace it with out changing any of the clearances?

  2. #2
    Super Moderator bmorgil's Avatar
    Join Date
    Dec 2018
    Northwestern Ohio
    Grouser, the service manual should help here. Basically, the seals that seal in the axle lube, are "inboard" on the model 25. They are right next to the Differential Carrier bearings. The intent is to keep the axle tubes dry to the knuckle, of the Gear lube. As we discussed on your other post, at that point, enter the knuckle lube. That's one reason why you need a fairly thick extremely viscous knuckle lube. So it doesn't run down the tube and it kind of stays in the knuckle.

    The seal has a very important and often neglected "Guide" piece that is pressed into the axle tube in front of the seal (wheel side). It is a small piece of tin shaped like a cone. It needs to go back in if it falls out. If you damage it it will have to be repaired. You cant buy them that I know of. Its purpose is to guide the splines of the axle shaft past the seal lips without cutting them. A very large problem in warranty. Seal leaks can almost always be traced back to installation damage. In this case Dana learned long ago that the seals can and did get cut, when the axle shaft was installed. OK all that cause I just want to emphasize a careful professional installation. That seal leaking is a number one complaint. Lose the axle lube and things go wrong.

    -Pull the axle shafts

    -Remove the carrier assembly. The shims are under the bearing cones on the diff. If you are not changing them, this is fairly straight forward. If you are changing them, it is not straightforward (and not covered here)! If you are not replacing the bearings, you will not be disturbing any settings.

    -With a seal puller or similar, pry the seals out. I have used a long bar from the wheel side on tough seals. This bangs up the above mentioned guide sleeve. You will need to straighten it up and put it back in if it is knocked out. Use the seal puller to be sure.

    -Clean the surfaces and coat the OUTSIDE of the new seal VERY LIGHTLY with silicone

    -Press the seals in DEAD SQUARE. if they are not square they will leak. The tool in the video below is the best way. I have made one with two large sockets the diameter of the seals, and a piece of all thread, washers and nuts.

    This is a model 30 but it is the same install note the tool.

    Axle Seal.JPG Inner seal.jpg
    Last edited by bmorgil; 02-05-2024 at 07:48 AM.

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