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Transmission Trouble

Discussion in 'Technical Discussion' started by Mito, Dec 28, 2020.

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  1. Mito

    Mito New Member

    Joined:
    Oct 7, 2020
    Messages:
    9
    Location:
    California
    Hello all, hope you all had some great gifts from Santa.

    I have a 52’ Hatteras with 8v92’s and Allison transmissions. I originally thought my port side starter was dragging or in need of replacement and after some troubleshooting, I discovered that the transmission was dragging.

    There is only like an 1/8” gap to get it into neutral, and that’s from the lever at the transmission (not the shifter). Once I get it into neutral, it’ll starter will spin no problem.

    Is there a way to adjust increase the play on the tranny to find neutral? It has nothing to do with cable adjustments, it’s about the play on the shifter lever on the tranny itself.

    Any tips would be appreciated!
  2. DOCKMASTER

    DOCKMASTER Senior Member

    Joined:
    Feb 26, 2012
    Messages:
    619
    Location:
    Ketchikan, Alaska
    Have you pulled your dipstick to make sure you don’t have a failed cooler and water in the oil? This can cause the clutches to swell and create a similar issue you are experiencing. This happened to me.
  3. Mito

    Mito New Member

    Joined:
    Oct 7, 2020
    Messages:
    9
    Location:
    California
    I did and did not see anything out of the ordinary but did not have oil checked.
    What was your remedy?
  4. DOCKMASTER

    DOCKMASTER Senior Member

    Joined:
    Feb 26, 2012
    Messages:
    619
    Location:
    Ketchikan, Alaska
    My remedy was to disassemble and overhaul the gear with all new clutches and bearings. I did manage to baby through the rest of the season when it happened though. Mine were not Allison though. They were Twin Disc behind 12v92’s. I think I did a thread on it when it happened on this forum.
  5. Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    9,204
    Location:
    Satsuma, FL
    Valve bodies on Allison clutches are rather simple and crude in design. A rotating shaft with holes and passages aligning up supplying oil flow towards different holes in the manifold. All functions kept separate by little O rings that take abuse from all directions years after years.

    IMO, your valve body seals (O rings and gaskets) are leaking. Your finding neutral just by balancing out the pressures to forward and reverse rather than no pressure to each.
    Find a real Allison shop and get the valve body resealed.
    Just resealing the VB is cheaper than getting a tech on site to prove or disprove my theory. But it's your ship and clutch.

    Don't think we can offer any more than this.