1980 Johnson lower unit spline issue

[ettenho1]

Hi All,<br /><br />A couple of weeks ago my lower unit gave out. Rather than rebuild it, I thought I would save myself a bundle by just buying a replacement used one, so I took the old one off and went on the hunt for a new(er) one. Lo and behold, I found a working one in good condition for very cheap. It was from a 1986 (mine is a 1980) but I was told that it would fit. Unfortunately, the '86 is a fine spline crankshaft, whereas my old one was a course spline shaft. Should I just sell the thing and try to find another one (course spline), or is there some way to make the thing match up? I don't have the special tools required to open up the gearbox, but how about the part that the shaft fits into in the powerhead (whatever that is)? I have the service manual but I don't see anything in there that solves my riddle. Any help is appreciated.<br /><br />Thanks,<br />Mark

 

[Dhadley]

Re: 1980 Johnson lower unit spline issue

Lets start by identifying the motor. We kind of assume (a bad thing) that its a 3 cylinder but before we say anything lets make sure that we're all talking about the same thing.

 

[ettenho1]

Re: 1980 Johnson lower unit spline issue

You got it, my engine is a 3 cyclinder 1980 70HP model J70ELCS.

 

[Dhadley]

Re: 1980 Johnson lower unit spline issue

Yes, what you have is the later model unit with the multi-splines. you need the unit with the 4 splines. You could change the shaft or the crank. Either is a bit of work. <br /><br />Another unit may be the easiest.