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Sm420 leak

Discussion in 'Early CJ-5 and CJ-6 Tech' started by FugginJim, Feb 24, 2009.

  1. Feb 24, 2009
    FugginJim

    FugginJim In control Sometimes Sponsor

    Norco California
    Joined:
    Nov 22, 2004
    Messages:
    365
    Well after a little searching apparently the early sm420s have a weep hole on the output shaft housing goin to the motor, are there any easy ways of sealing this up. I actually thought I had a rear main seal leak and replaced it while still all together, not knowing this was a possible source. Leaks definitely annoy me. Thanks for all input.
     
  2. Feb 24, 2009
    nickmil

    nickmil In mothballs. Sponsor

    Happy Valley, OR
    Joined:
    Sep 23, 2002
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    11,429
    Are you talking about the input shaft and the front bearing retainer? The input shaft is the part that is splined inside the clutch disc and the front bearing retainer holds the input bearing in place as well as the input shaft. The throwout bearing also rides on the front bearing retainer. If so, the early 420's didn't have a seal between the input shaft and front bearing retainer. The input shaft had "threads" machined in it that as it rotated directed the oil back to the transmission case. Not the most positive seal to be sure. Going down hills and what not oil would work it's way past the "threads" so there has to be a weep hole in the bearing retainer. If that's not there, then the oil works farther up towards the engine, comes out between the bearing retainer and input shaft, and soaks the clutch with oil. Not good. In short, If you are talking about what I've described, then no, unfortunately no good way of sealing the weep hole.
     
  3. Feb 24, 2009
    mitch

    mitch New Member

    western Mass
    Joined:
    Aug 16, 2007
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    3
    Novaks has a replacement front seal and retainer , (#420FS) that is supposed to eliminate that issue.
     
  4. Feb 24, 2009
    nickmil

    nickmil In mothballs. Sponsor

    Happy Valley, OR
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    You'd have to change the input shaft as well so there would be a place to seal against.

    Edit: Ahha! They say on their web site they will machine the seal surface into the customers input shaft! Well done!
     
    Last edited: Feb 24, 2009
  5. Feb 25, 2009
    FugginJim

    FugginJim In control Sometimes Sponsor

    Norco California
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    Nov 22, 2004
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    365
    Nick this is what I was trying to describe. So Novak does what I need but what is involved in removing the retainer and input shaft to send out them.
     
  6. Feb 25, 2009
    nickmil

    nickmil In mothballs. Sponsor

    Happy Valley, OR
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    Obviously the tranny has to come out. The front bearing retainer is held on with 4 bolts so no issue there. The SM-420 I did last week you could line up the cutout in the dog teeth on the input gear with the counter gear and pull it straight out. Didn't even have to remove the bearing, although the retaining ring would need to be removed and the bearing pressed off before sending it in to Novak. Be aware that when you remove the input shaft the pilot or pocket bearings between the input shaft and output shaft will come out and want to fall into the bottom of the transmission so be ready with a small magnet to pick those out. You can use vaseline to hold them in place in the input shaft on reassembly. Also make sure you use the same thickness gasket between the front bearing retainer and case as you have now.
     
  7. Feb 25, 2009
    FugginJim

    FugginJim In control Sometimes Sponsor

    Norco California
    Joined:
    Nov 22, 2004
    Messages:
    365
    Thanks Nick for the help always good info gonna run this tranny 1st if it seems sound then Ill invest in doing the front seal with Novak.
     

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