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Dana 18 And Speedo Gears

Discussion in 'Flat Fender Tech' started by DanStew, Dec 20, 2021.

  1. Dec 20, 2021
    DanStew

    DanStew Preowned Merkin salesman Staff Member

    Lexington, South...
    Joined:
    Sep 22, 2002
    Messages:
    4,585
    I am am at the end of my Dana 18 rebuild but am having a heck of a time shimming the rear output. Originally i got it to the correct endplay but when i tightened it after spraying the spray sealant on the shims it is super tight and the gears hardly turn without super power.I pulled it apart and nothing shifted. I did notice once i loosened the bolts it was able to turn, OK I played with more shims and it seemed to get better. but when i torqued down my yoke it was very difficult to turn. So i am bashing my head in trying to think what the issue is. I did notice when i turned the yoke it seemed to be feeling weird where the speedo gears meshed.

    Then i realized when i got my first endplay measurement the speedo gear was not on the shaft, but i did put it on when i bolted it up complete.

    I replaced the small speedo gear because it was chewed up and the case came out of a 71 CJ5 so the axle gears were higher. I ordered one for the early jeeps with 5.38 gears.


    That being said is the large round gear on the output shaft matched to the smaller gear?

    This is the 3rd Tcase i have rebuild and i have never had this problem
     
    DanStew, Dec 20, 2021
    #1
  2. Dec 20, 2021
    DanStew

    DanStew Preowned Merkin salesman Staff Member

    Lexington, South...
    Joined:
    Sep 22, 2002
    Messages:
    4,585
    I just came out of the garage again playing with things. with all speedo gears installed, no play. just the large speedo gear. i get end play. remove large speedo gear and just the small one installed. I get end play. So i am going to put blame on the new small gear. the large one was original to the Tcase. :(.
     
    DanStew, Dec 20, 2021
    #2
  3. Dec 20, 2021
    duffer

    duffer Rodent Power

    Bozeman, MT
    Joined:
    Sep 17, 2009
    Messages:
    4,497
    How do the lengths compare?
     
    duffer, Dec 20, 2021
    #3
  4. Dec 20, 2021
    DanStew

    DanStew Preowned Merkin salesman Staff Member

    Lexington, South...
    Joined:
    Sep 22, 2002
    Messages:
    4,585
    lengths are the same. tooth count is different. I am guessing the Dana 18 is not like an NP231 where you can change the outer gear and not have to mess with the inner.
     
    DanStew, Dec 20, 2021
    #4
  5. Dec 21, 2021
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
    Joined:
    Sep 23, 2002
    Messages:
    12,529
    No it is not. The tooth counts of the output gear on the output shaft must be compatible with the driven gear for the speedometer drive.
    When rebuilding an 18 here is what I do for the rear output. Install front output and housing. Then start setting up the rear. Make sure ALL components for the rear output are installed except the seal and speedo driven gear. This includes the rear yoke and nut torqued as this sets everything in place. Adjust your preload or endplay accordingly. After everything is set then install the rear output seal all the way down to the step in the rear output housing. Failing to do this can cause the dust shield on the rear yoke/companion flange to hit the seal shell and cause binding. Then I install the speedometer driven gear and retainer/housing. Following this I’ve had no issues since I figured this procedure out. I don’t use that spray sealer either. I use generally RTV Ultrablack. Put it on thin and never had an issue with it changing clearance on the rear output and much easier to remove down the road than that spray crap.
    Ymmv of course.
     
    nickmil, Dec 21, 2021
    #5
    Ol Fogie, DanStew and dnb71R2 like this.
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