Johnson 82 35 Hp, 91 25Hp 01 25Hp Interchangeable Lower Units

Discussion in 'Outboard Maintenance' started by Tom_C, Jul 21, 2009.

  1. Tom_C

    Tom_C Well-Known Member

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    I have a 1982 35 Hp 20 inch shaft that was suppose to be running great. So I mod the Jack Plate with Tilt that I make so the 20 inch shaft would work on my Gheenoe that the transom is made for a 15 inch shaft. It sounds great but has a bad clutch dog and maybe bad gears.

    I also have a 1991 25 Hp 15 inch shaft that runs ok but may need to be rebuilt soon.

    And I have a 2001 25 Hp 15 inch shaft that has a bad power head.

    What I like to do is to swap the 1982 35 Hp Power Head in to the 2001 25 Hp chassis, and keep the 1991 25Hp as a spare.

    If I can't do that can I swap the gear cases between the 1991 or the 2001 25 Hp with the 1982 35Hp?


    Before Jack Plate mod:1991 25Hp with a 3x10x12 Al prop:

    [​IMG][​IMG]

    After mod: 1982 35Hp with a 3x10x15 SS prop.
    [​IMG][​IMG]
     
  2. Brett

    Brett > PRO STAFF <

    1982 35 gearcase parts list:

    http://www.crowleymarine.com/brp_parts/diagrams/27276.cfm

    2001 25 hp gearcase:

    http://www.crowleymarine.com/brp_parts/diagrams/27781.cfm

    Looks like both gear cases have the same part parts number.

    Exhaust housing 1982 35hp

    http://www.crowleymarine.com/brp_parts/diagrams/29066.cfm

    Exhaust housing 2001 25hp

    http://www.crowleymarine.com/brp_parts/diagrams/28086.cfm

    Exhaust housing assemblies...same parts number


    Some people read the morning paper with their coffee,
    I browse parts catalogs, I'm so easily entertained....

    ;)
     

  3. goodhands_gheenoer

    goodhands_gheenoer Well-Known Member

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    Sell all 3 motors and buy a new one?
     
  4. rkmurphy

    rkmurphy Well-Known Member

    Yeah Tom I say get rid of all 3 and pick up LoneRanger's 2000 25 hp Johnson. That way you have something a little newer that's been treated nicely and a new place to start. These motors are supposed to be bullet proof and I don't think you'll notice a difference between the 25 and 35 Johnson. Same motor and weight.

    Get 'er fixed so I can see you run it with all of that stuff bolted on the back at the next bash!!
     
  5. Un-shore

    Un-shore Well-Known Member

    Are you mainly concerned about the gear ratios?
     
  6. Un-shore

    Un-shore Well-Known Member

    From what I've learned about outboards, if they look the same on the outside they are the same on the inside except for gear ratios and drive shaft lengths.

    From a mfg standpoint, they are not going to reinvent something for no reason.
     
  7. Frank_Sebastian

    Frank_Sebastian Well-Known Member

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    On the 82 you may want to consider swapping the gears and turning the dog around. The reverse wouldn't do too good, but it might run for a long time time like that.

    Frank_S
     
  8. Brett

    Brett > PRO STAFF <

    Neat trick Frank, thanks!
    I'll store that one in the shop manual.
     
  9. Tom_C

    Tom_C Well-Known Member

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    Thanks, everyone.

    Frank that's a good idea, I need to pull it apart and see what kind of shape it's in.

    But, for now it's on hold Lorrie Dad is not doing well and is in the Hospital in Sacramento Ca. :(

    I realy hope I can get the 35 going, other than the clutch dog, she sounds GREAT, better than the 91 25Hp.
     
  10. Tom_C

    Tom_C Well-Known Member

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    On swapping the 82 35HP in the 2001 25HP the chassis looks good, but I need to find out if the 15 inch drive shaft gear will mesh with the 35HP.
     
  11. Peter2006

    Peter2006 I Love microskiff.com!

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    The 1982 powerhead is different and so is the belly pan and all shift and throttle parts.
    Exhaust housing down it's the sames
     
  12. Tom_C

    Tom_C Well-Known Member

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    Help I must be blind, I don't see the same P/N.
     
  13. Brett

    Brett > PRO STAFF <

    I agree, now they don't have the same numbers.
    Curious, wonder if the site modified the page.
    Or if I had too many webpages open at the same time.
    I'd go with too many pages open and I fouled up.

    :D
     
  14. Kemo

    Kemo The world is flat....and shallow.

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    Brett "fouled up".  I'm putting this on my calendar.   ;D

    Just kidding, Bret.  You are STILL The Man.

    Kemo   :cool:
     
  15. Tom_C

    Tom_C Well-Known Member

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    Thank God, I was think I'm going blind, what next! [smiley=1-crazy-eyes.gif]

    The 91 and 01 are the same. [smiley=1-thumbsup3.gif]
     
  16. Tom_C

    Tom_C Well-Known Member

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    Easy pulled the gear case apart for me and this is what we found.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    I also was given a gear cass from about the same year as my 35. The hope was I could used the lower unit. I should of looked a little closer but I bought a water pump and found out I was out of luck. I tried to installed the drive shaft and this is what I found.

    [​IMG]

    I pulled the drive shaft out of the 2001 to compare it.

    [​IMG]
     
  17. Flyline

    Flyline Won &quot;Do More With Less&quot; Award!

    Any updates Tom?

    There's 1984 35hp lower unit with alum. propeller (looks new prop but fade out in the sun) in good condition. It's short shaft lower unit.

    He wants $350.00 for it

    Doug's outboard
    407-656-8396

    Trying to help you out.
     
  18. Tom_C

    Tom_C Well-Known Member

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    Thanks whitesnooky,
    but the 84 lower unit is not interchangable with a 83.
    It need to be between 77 and 83.
     
  19. Flyline

    Flyline Won &quot;Do More With Less&quot; Award!

    ummm but the lowerunit looks exactly like yours as I seen the picture....the older moder 77-83 has no plastic sqaure sides where the water goes in the lowerunit.

    The Mechanic may be wrong about the year...

    U're welcome :)