1985 50 HP Johnson lower unit interchange?

[reelfishin]

I picked up a good running 1985 Johnson 50hp last week, I originally just grabbed it as a parts motor but as it turns out, it's great running motor with 145lbs compression on both cylinders.
The power pack and rectifier were bad, so I guess they wrote it off as junk.
The only problem now is that the lower unit is pretty abused, the skeg is ground down to about 1/4 the size it should be, the bullet is dented and the anti cavitation plate and upper fins are broken in several places. It was run in a rocky river bed area all of it's life an the lower really took a beating.

My question is, what other year lower units will interchange with this motor?

 

[tashasdaddy]

Re: 1985 50 HP Johnson lower unit interchange?

i went back as far as 1980, 1980-1985 use the same drive shaft. there is a number change in 1986. you can check further back to see.

 

[James R]

Re: 1985 50 HP Johnson lower unit interchange?

If the unit is in good working order, no leaks, no water in the oil,no metal bits in the oil,straight shafts with good splines, shifts well, then with a little welding it can be fixed. My welding man does a great job.

 

[Gary H NC]

Re: 1985 50 HP Johnson lower unit interchange?

Hey James....sending you a PM..

 

[reelfishin]

Re: 1985 50 HP Johnson lower unit interchange?

If the unit is in good working order, no leaks, no water in the oil,no metal bits in the oil,straight shafts with good splines, shifts well, then with a little welding it can be fixed. My welding man does a great job.

I can weld it up but its pretty bad, I'd have to rebuild the skeg, and almost all of the fins, and fix the dent in the nose cone area. It's not leaking, but I can't imagine the internals are much good after being beaten to death on rocks.
What surprised me was how clean the rest of the motor was, usually when a motor is this abused, the whole thing is junk. The upper is super clean, not hardly a scratch.

 

[reelfishin]

Re: 1985 50 HP Johnson lower unit interchange?

i went back as far as 1980, 1980-1985 use the same drive shaft. there is a number change in 1986. you can check further back to see.

I know there were a lot of changes in or about 1987, the whole design changed and the motor got smaller or lighter.
The housing is the main concern, if it will bolt up, I can swap out the rest as needed. I tried going back and checking housing numbers but nearly every year is different for some reason, and I know that there weren't that many changes.
Did the earlier 50's also have hydro mechanical shifting or did they go right from electric shift to mechanical shift?

I've also seen a few 50hp motors with the larger lower unit, which swap with the three cylinder motors. My 1978 55 has the same lower as my 1980 70hp. The parts book however lists them as totally different numbers. I also have another 1978 55 HP for parts, its got the smaller gear case, besides being shorter, it also uses a smaller prop hub. Possibly the short shaft versions all used the lighter gear case?
The gear case on the 1985 50 is ligher duty looking than that of my 1978 55hp, but it looks like a taller version of the one on the short shaft parts motor. The '85 is a 20" shaft, the '78 is a 15" shaft.
I know the 50hp motors changed the most when the incorporated the internal tilt and trim in 1987, it was pretty much a different motor.

I have the chance to pick up a 1975-76 motor with a blown power head and good lower, I need to find out if that motor used the same housing.
When I look up the part number at BRP, they list it as an assembly either complete or as a case with bearings, not a bare case, so it may only be a bearing change that's different.
I know that if I look up a V4 lower, they list several from 78 to 92, but there are basically only two sizes, one being the same as a V6, the others are all swappable. I was wondering if it was the same with the larger twins?

 

[tashasdaddy]

Re: 1985 50 HP Johnson lower unit interchange?

61-67 some were mechanical, some were electric shift, 68-72 were hydro-electric shift, 73-76or 77 were hydro- mechanical, 78 up are all mechanical shift, but with many changes. i think in the years i gave you they should work, but not guaranteeing it.

 

[reelfishin]

Re: 1985 50 HP Johnson lower unit interchange?

61-67 some were mechanical, some were electric shift, 68-72 were hydro-electric shift, 73-76or 77 were hydro- mechanical, 78 up are all mechanical shift, but with many changes. i think in the years i gave you they should work, but not guaranteeing it.

That's pretty much what I was wondering, I wasn't sure if the 50hp motors went to hydro mechanical or if they were all straight mechanical.
I know 72 and back motors were Hydro Electric Shift.
When I was looking for an early style, all I could find was later lower units, now I need a newer one, and can only find early ones.

 

[James R]

Re: 1985 50 HP Johnson lower unit interchange?

Gary H. I tried answering your PM but it did not go through. E me.
osborassoc@aol.com.
James.