Swapping lower units on 1997 115 hp Johnson with 1989 90hp Johnson

[Dani1989]

Good day everyone, I am wondering if I could swap my lower unit of my 115hp Johnson (1997) onto my motor of (1989) 90hp Johnson. The difference I noticed what the drive shaft.

 

[Dani1989]

I just want to add that I put it on and put it on the water. There was a lack of full power but also noticed another issue my bulb collapsed when driving but went back to normal went I put it in neutral.

 

[racerone]

The lower unit has nothing to do with the bulb collapsing.-----Check tank pick up tube.----Check tank vent.------Anti syphon valve.-----There is a restriction between bulb and fuel in the tank.-----What did you do to install the newer lower unit on your older motor?----Those newer lower units are not as robust in my opinion.

 

[Dani1989]

Thank you will check those for the bulb collapsing.
As for the lower unit I just removed it from my 89 Johnson and then removed from the 97 Johnson and put it in and it worked. Just the problem of no full power. Which I’m unsure if it was due to the lower unit or the bulb problem.

 

[racerone]

Did you change the shift rod ?-----Did you adjust the shift rod to the correct height , yes ,no or no idea what is involved here?

 

[Dani1989]

Did you change the shift rod ?-----Did you adjust the shift rod to the correct height , yes ,no or no idea what is involved here?

To be honest I have very little knowledge about boats. But I did not switch the shift rod as it looked the exact same. Also I measured it to what the other rod came out as. I got it in no problem so I thought it would be fine. :/

 

[racerone]

In your pictures the shift rods appear to be different at the top.----But if you and the motor are happy then all is good.

 

[Dani1989]

the motor not I am happy with what is going on lol. The shift rods are the small ones with the holes in them correct ? Those are the two. I’m kind of confused as to what is different ? Please explain. Should I pull the lower unit and swap the shift rods ? I’d be happy to do so if that would be the problem to loss of power.

 

[Dani1989]

the motor not I am happy with what is going on lol. The shift rods are the small ones with the holes in them correct ?

 

[Dani1989]

In your pictures the shift rods appear to be different at the top.----But if you and the motor are happy then all is good.

It may be the pictures but I honestly believe they had the same curve and everything seemed the same as well.

 

[Dani1989]

It may be the pictures but I honestly believe they had the same curve and everything seemed the same as well

In your pictures the shift rods appear to be different at the top.----But if you and the motor are happy then all is good.

should I remove and make sure and also remeasure? I will do anything to get my boat working properly.

 

[Dani1989]

I guess I should mention the lower unit from the 1997 115hp went on the 1989 90hp.

 

[Dani1989]

Can someone help please

 

[Scott Danforth]

you have lower units from two different vintages. you are going to have to do a lot of work to get it to work. two different style drive shafts, two different style shift shafts. what else has changed over the years.

just because the mounting bolts line up, doesnt mean it will work.

 

[racerone]

See post #7 and post #10----I have stepped aside.

 

[Dani1989]

you have lower units from two different vintages. you are going to have to do a lot of work to get it to work. two different style drive shafts, two different style shift shafts. what else has changed over the years.

just because the mounting bolts line up, doesnt mean it will work.

Okay. Can I just swap the shift shafts ? And what do I have to do with the drive shaft ? Can I just swap those ?

 

[Dani1989]

I am willing to do the work. Just need a little guidance please to get me going in the right direction.

 

[Scott Danforth]

Okay. Can I just swap the shift shafts ? And what do I have to do with the drive shaft ? Can I just swap those ?

Open up the parts manuals and service manuals, however you will find that there have been a fair amount of changes that happened between 1989 and 1997.

 

[ct1762@gmail.com]

i'm fairly certain you CANNOT put the 1992 and later longer driveshaft into a 1991 and older motor as it will bind and put extreme load on the lower bearing. I tried that once and ran it on the hose for 10 seconds . after hearing a whirring noise i shut it down and grabbed the correct gearcase!

 

[Dani1989]

i'm fairly certain you CANNOT put the 1992 and later longer driveshaft into a 1991 and older motor as it will bind and put extreme load on the lower bearing. I tried that once and ran it on the hose for 10 seconds . after hearing a whirring noise i shut it down and grabbed the correct gearcase!

Thank you for this advise. ! Would it be different that I put the 97 (shorter) one onto my 89 (longer) one.