50 Hp Mid 70's Merc lost reverse replacing lower unit

Discussion in 'Outboards' started by 32dash, Jan 9, 2010.

  1. 32dash
    Joined: Jan 2010
    Posts: 1
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    Location: nj

    32dash New Member

    I Have A ? About A 50 Hp Mid 70's Merc. I Had To Replace The Lower Unit And When I Did I Lost Reverse. Is There An Easy Fix, All I Did Was Unbolt The Unit And Relace It With A Similar One. It Went To Gether Easy. Why Would I Lose Reverse. Any Help Would Be Great.
    Thanks
     
  2. Obsession
    Joined: Jan 2010
    Posts: 68
    Likes: 3, Points: 0, Legacy Rep: 35
    Location: Chicago, IL, USA

    Obsession Junior Member

    Hard to diagnose without seeing what the shift mechanism is doing now. If you can't shift it manually by giving it more throw may have to take the new lower off again and see if it shifts manually, then see how the shift shaft is meshing differently from the old unit...
     
  3. kenJ
    Joined: Jul 2005
    Posts: 349
    Likes: 5, Points: 0, Legacy Rep: 56
    Location: Williamsburg, VA

    kenJ Senior Member

    Need more info. If the lever moves into the reverse postion but nothing happens then you probably have the linkage misaligned. If it will not then the lower unit is suspect. There are also some safeties, if the throttle is advanced too far it should not shift into reverse. On some the anti kick up mechinism must also be locked in position.
     
  4. Frosty

    Frosty Previous Member

    Did you check the lower unit for reverse before you installed it?
     
  5. powerabout
    Joined: Nov 2007
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    Location: Melbourne/Singapore/Italy

    powerabout Senior Member

    yer what Frosty said
    then

    Without the tool...grab the shift shaft as low as you can with some soft jaw pointy vice grips
    It should move easily if it has rotated off the cam and the box will be in forward, (clockwise drive shaft, right hand prop)
    Rotate the shift shaft anticlockwise (while spinning the prop back and forward) and it will become firm and you will feel a notch as it goes into neutral.
    (If you want to test it keep turning and it will go into reverse)
    ( The shift cam/shaft can most probably rotate 360)
    Then make sure your control is in neutral and try to put it back up.
    There is a small plastic guide to help guide the lower shaft into the adapter in the upper which is inside the swivel tube, without that you will need to get a 2nd person to help line it up.
    You might slip the control cable out of the retainer so you can move the shift a small amount to ensure it lines up

    If you engine does not have power trim let me know as that a bit harder to work with.
     
  6. Frosty

    Frosty Previous Member

    Might not be a rotating movement, but an up and down.
     
  7. cummingknives
    Joined: May 2010
    Posts: 12
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    Location: Cedar Crest

    cummingknives cummingknives

    I think the lost reverse is there somewhere. Use a flashlight to see better. These things just don't grow legs and walk off at night.
     

  8. CDK
    Joined: Aug 2007
    Posts: 3,324
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    Location: Adriatic sea

    CDK retired engineer

    The splined end of the shift shaft can be inserted in the lower gearbox coupler in 6 different positions of which 5 are wrong and only 1 is correct. If you had kept the throttle handle in reverse AND the gearbox (with one hand against the prop to keep it there), you would not have posted this question.

    Why all the Capitals? It doesn't read easier.
     
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