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Change lower unit 50hp Evinrude 75hp Johnson, both short shaft

L

Larsfromdenmark

New member
Hello Experts, i am writing you from Denmark, we have no experts here....:eek:
I am the lucky owner of a beautiful vintage boat. It needs a short shaft engine. I have a nice 50hp 1975 Evinrude short shaft. Runs Perfectly, but i need a bit more power, and as you know it is very difficult to find short shaft engines with more than 50 hp. Now I found a nice Johnson 75hp 1981, short shaft, but the lower unit is broken. As far as i know the lover unit is the same on these two engines except from the gearratio. The question is : Would it still be possible to take the lower unit from from the old 50 hp and put it on the 75hp and then just live with another gearratio ? Will it fit ?
Thanks in advance for your help !

Lars from Denmark
 
The housing and propshaft are the same when you say broken what is wrong with the 75hp gearbox? You would need to swap driveshafts to do that you need to disassemble both gearboxes.
 
kimcrwbr1 said:
The housing and propshaft are the same when you say broken what is wrong with the 75hp gearbox? You would need to swap driveshafts to do that you need to disassemble both gearboxes.
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Thanks guys for very helpfull replys
Water has been in the gearbox of the 75hp, so everything i rusty. Is it really possible to take driveshaft of the 75hp and swap it to the lower unit of the 50hp ? -that is a great idea !
Is it a problem with different gearratio ?
/ Lars
 
Racer will know better but I doubt you would be able to find a prop to work properly. If the driveshaft is in good condition it will fit but it needs to be shimmed properly you cannot just swap it out. The only other issue would be the pinion splines and the 75hp gears may be alot beefier. Your best bet is to keep looking for a bigger motor that way you can still sell the 50hp in good condition and get a good price for a complete motor.
 
kimcrwbr1 said:
Racer will know better but I doubt you would be able to find a prop to work properly. If the driveshaft is in good condition it will fit but it needs to be shimmed properly you cannot just swap it out. The only other issue would be the pinion splines and the 75hp gears may be alot beefier. Your best bet is to keep looking for a bigger motor that way you can still sell the 50hp in good condition and get a good price for a complete motor.
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Thanks Kim.
You have a point. Or maybe look for a refurbished gearcase for the 75hp. What do you say Racer ?
 
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