1977 55HP Johnson Outboard Lower Unit

rjcamel2355

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Apr 22, 2015
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Does anyone happen to know what year/HP Range will interchange? A friend of mine had his lower go down on him over the weekend, and I've decided to help him search for a replacement.

Thank you!
 

gm280

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Jun 26, 2011
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What exactly is wrong with his lower unit? Parts can be found for them yet.
 

rjcamel2355

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He was running it across the lake a few months back, and it shut down (locked up) towed it back for him, and he finally got around to taking a look at it. Lower unit was full of water, no gear lube. Got it to break free, filled it up with lube, and it did good for about a 4 mile trip, before it started grinding and such.

I could be wrong, but I imagine a used/reman one is a little cheaper than having one rebuilt....
 

racerone

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Dec 28, 2013
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It will shock you on price of repair parts.---Good used if there is such a thing is the way to go.-----Find a donor motor is often the best way.----Those lower units are not known for durability. and are not robust.
 

mlaajanen

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Apr 18, 2016
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It will shock you on price of repair parts.---Good used if there is such a thing is the way to go.-----Find a donor motor is often the best way.----Those lower units are not known for durability. and are not robust.

What are there durability problems and what is not robust in the design?
 

racerone

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Pinion gear is known to shatter.----Clutch dog is known to shatter.-----That is why the 2 cylinder motor gets a hybrid 3 cylinder lower unit for commercial use.----The 3 cylinder motor uses a 3 cylinder lower for commercial use.
 

rjcamel2355

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Would a 70hp johnson of the same era (76-78ish) be interchangeable or no? I know the 70 is a 3 cyl and the 55 is a 2cyl
 

Watermann

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Pinion gear is known to shatter.----Clutch dog is known to shatter.-----
.

My 77 55 HP has had no such issues and I'd like to see that super robust LU that can run water. Because of the age of the motor I suspect the seals were bad as I had to replace mine. There's nothing wrong with these LU's if you keep gear oil in them.

Would a 70hp johnson of the same era (76-78ish) be interchangeable or no? I know the 70 is a 3 cyl and the 55 is a 2cyl

No the 70 uses a large gear case with a different gear ratio. You'll most likely find it easier to find a replacement motor than a new LU for the motor and sell the 55 power head. Too bad your buddy didn't spend 20 bucks on new seals.
 
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