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Thread: 1999 subaru legacy GT center differential replacment

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    1999 subaru legacy GT center differential replacment

    so I recently purchased a 1999 Subaru legacy GT 5MT and the center differential is bad. It has all the tell tail signs, binding under tight slow turns, clattering when decelerating in gear, the hole nine yards. Does anyone have a good service manual or walk though on how to replace the center differential. I plan on doing it myself but I would like to know all the things I need to know first. Any tricky parts? special tools? things I need to watch out for? what should I replace while I'm there? Any help would be tremendous. Thank you

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    Center diff replacement is very straight forward. You can do it with transmission in the car.

    First, you need to remove the whole exhaust system (or if yours is not rusted together, you can only remove from the first cat to the back muffler...).
    Then you remove the rear prop shaft and shift linkage.

    After that you remove back transmission mount.
    Then you remove center diff back cover and there is the center diff.
    DSCN5436_384687e8-c983-48a9-813c-f8ba65b6b939.jpgsubaru-manual-transmission.jpg

    All you have to do is remove the old one and in with the new one.

    But if you want to save a few bucks, you can replace new style center diff with used old style, wich lasts longer and wont break under normal usage.
    If you want to change new to old center diff there is a bit more work. You have to whole replace center diff housing, but it is nothing more difficult, because you allready have diff out.
    If you decide to go this way, tell me, I have done this and I am very pleased. So I can help you with information.

    I hope that this post is helpful to you.
    Sorry if I made some mistakes in writing, because I am not an English speaker.

    Greetings from Slovenia!
    Subaru Legacy GL EJ20 (BH, year 2002)

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    thank you for the help and your English is fine. Do I have to worry about shims and stuff like that? from the research I did, I know that the differential itself does not have shims but the input gears (9 and 7 on the diagram you provided) do have shims. are they easy to loose?

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    I did not have any problem with shims.
    I think that output gear/shaft assembly (shaft above the center diff), has a couple of shims, but they are pretty big, so you shouldn't worry about loosing them too much.

    If you assemble it in the same way you disassembled it, there should not be any problems.

    I had more problems with shifting linkage, prop shaft and exhaust removal than with disasembly and asembly of the diff housing and replacement of the diff itself.

    So will you just replace the diff with the same model or will you replace it with the older model diff?

    Also, before you begin, read the Workshop/Service manual. I'm writing this purely out of my head, so I almost certainly forgot something....
    Subaru Legacy GL EJ20 (BH, year 2002)

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    It all depends on what I can find. the cheapest diff I can find right now is the same year make and model but if I can find a better one I may do it and I'm not sure what service manual you're talking about. I'm very new here so I'm still trying to find my way around.

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    Subaru Legacy GL EJ20 (BH, year 2002)

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    thank you for your help. this info should help a lot.

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    hello so now I'm trying to find a center differential and its a real pain in the ass trying to find a used one for the exact same year. does anyone know what makes and models share the same center diff? I've heard that all the 5mt transmissions have basically the same center diff.

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    Any normal (not STi...) 5mt center diff will fit.

    You only have to decide if you want to replace whole housing for one generation older or just replace diff itself for the same generation.
    Subaru Legacy GL EJ20 (BH, year 2002)

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    so I just spent the day pulling the center differential out of a base model 1999 legacy wagon with a 5mt to put into my 1999 legacy gt sedan just to find that the differential assembly does not fit what so ever. it's very close but completely useless. on the outside they look completely different but once you start looking in detgail they look like 2 different vesions of the same thing. from what i can tell the differential out of the wagon does not spline onto the output shaft of the transmission and the rear output shaft bearing does not fit in the hole for the race. any ideas?

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    Please take a picture of both center diffs and housings, so we will know what you are working with.

    You should be able to change the whole cente diff asembly including the housing - this is what I did.
    Subaru Legacy GL EJ20 (BH, year 2002)

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