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Center diff interchange question

Posted by vinnybean, Oct 1, 2008

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  1. vinnybean

    vinnybean Proven Member

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    Joined Aug 12, 2006
    Methuen, Massachusetts
    I have a 93 gsx and i blew the center diff (surprise!). My question is if i get a used shep 4 spider diff out of a 1992 will it work in my 1993. I read the info on jacks regarding gear set identification. From what i understand my 1993 SHOULD...have the center diff with the slash on the gear. And the 92 SHOULD also. If they both do will they interchange? Also how can you check center diff preload?
     
  2. ->PrOjEcTGS<-

    ->PrOjEcTGS<- Proven Member

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    Joined Oct 14, 2002
    , Missouri
    Should work.

    Check the preload with some solder. Put the solder between the case and the bearing race without the shims. Then put the case together and torque it down. Then, remove the case and solder. Measure the solder. The measurement you have is no preload or endplay. Add to that measurement your preload and order shims that are closest to that calculated measurement! :thumb:
     
  3. dazzellerr

    dazzellerr Proven Member

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    Joined Dec 15, 2007
    boise, Idaho
    from my computer here at the shop, the only difference i forsee in the swap is if one is an auto and one is a manual. must have something to do with the axle shafts, edit, just checked the shafts, seem they are the same auto or manual 92-94. the gear ratio might be different then as the manual trans is a 3.55 and the auto is a 3.31 ratio. that will mess with things if you have a 3.55 in the front.

    this probably has nothing to do with a shep diff since i looked up a rearend. :(
    21, 22, or 23 spline on the tranny.
    anyways, i will quit rambling on with this worthless info.:(
     
  4. ->PrOjEcTGS<-

    ->PrOjEcTGS<- Proven Member

    1,786
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    Joined Oct 14, 2002
    , Missouri
    He's talking about the center diff not the front diff...

    Axles go into the front diff and he won't be swapping that, so he won't have a problem there.

    Also he shouldn't have a problem with the spline count on the output shaft to the transfer case since wouldn't be changing any of that stuff either. The only reason people have problems with the spline count is if they are trying to put a transfer case from an 22 spline 1990 car into a 23 spline 1991-1996 car or vice versa. You need the output shaft to mate the respective t-case.

    97-99 are 23 spline but they have a different internal ratio all of their own. They're special.

    None of this information pertains to the OP's original question just a corrective to the misinformation given.
     
  5. vinnybean

    vinnybean Proven Member

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    Joined Aug 12, 2006
    Methuen, Massachusetts
    Thanks for the info. I was having a hard time trying to figure out how to set preload without a factory service manual. it is time to invest in one.
     
  6. dazzellerr

    dazzellerr Proven Member

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    Joined Dec 15, 2007
    boise, Idaho
    yeah, i figured that out once i was half way through typing. i will admit ti, my bad LOL.

     
  7. GRNDSM

    GRNDSM Moderator

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    Joined May 16, 2002
    Chelmsford, Massachusetts
    All 92-94 five speed center diffs are interchangeable (90 is different and 91 is an oddball year with both type of gears). So you should be all set. However, just to be safe, you should always check for compatibility by the lines on the face of the gear (90 has no line and 92-94 has one line on the diff housing and a matching line on the intermediate shaft).

    As for shimming, it is a good idea, but I have never done it and never had a problem with this… And no one I know (aside from a tranny shops) does it, ether. You would think that there are many problems caused by this, I just haven’t seen it. This leads me to beleive that shimming on the diff is not as important as shimming on the two gear shafts.
     

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