115 hp johnson lower unit

J

johnson86

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I have a 1977 115 hp johnson. The lower unit has a crack in it. My buddy at work has a 1979 115 Johnson lower unit. My research shows a different part number for 1978 and up. It looks just like my 1977 unit. Does anybody know the difference between the two or are they actually compatible? Thanks for any help.
 
J

johnson86

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Re: 115 hp johnson lower unit

Thanks. The part numbers are different but the two units look very similar. his doesn't have a waterpump on it so i can't tell if that's the difference. maybe the cooling systems are different? I'd hate to put it on and cause damage. When I looked on ebay for a lower unit it seems like the 1977 was by itself.
 
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Daviet

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Re: 115 hp johnson lower unit

Look in The Top Secret file at the top of the page, I think there is an interchange list there.
 
J

johnson86

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Re: 115 hp johnson lower unit

Daviet said:
Look in The Top Secret file at the top of the page, I think there is an interchange list there.
Click to expand...

Thanks. It looks like 1978 and newer is all by itself. It's odd though because the 1979 looks so much like my 1977. I guess I'll have to look for a 1977 style lower unit for a 115 hp. I'd hate to get the 1979 and find out something odd is different. If anybody has one let me know. Thanks.
 
W

WavyD

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Jun 28, 2010
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Re: 115 hp johnson lower unit

what model # is your 115 ?
i see 3 model #'s each with diff units...

check back in time (pm me or search WavyD) because if i cannot get
my 1979 85hp working i will part it out and from what i understand my lower unit will fit yours....we'd have to get a positive confirmation of course.
i believe my lower unit is 389820.
(85TL79R)
 
E

ezeke

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Sep 19, 2003
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12,532
Re: 115 hp johnson lower unit

The standard 20" 1977 115 has the gearcase used from 1973 through 1977.

Look at the back line of the skeg; if it is perpendicluar to the prop shaft, it won't cross to the gearcases with the back line of the skeg angled back.

The earlier units are hydraulically assisted and shift opposite of the later ones.
 
J

johnson86

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Dec 23, 2009
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Re: 115 hp johnson lower unit

I am a big dummy. I checked the model number and it turns out I have a 1978. No wonder the 1979 looked the same, it is the same. FWIW the 1977 and older is different than the 1978 and newer. The 1977 seems to be a hydraulic assist shift and the newer models are mechanical. Im told the linkage is different. Thanks for all your help guys.
 
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