Parts interchange

[IMPERIAL16]

i have my 1964 evirude starflte 90s 90hp that the lower unit dont shift into forward or reverse. its an electric shift. now my ? is what are the yrs and hp that i can interchane the lower unit from i bought a 1968 evinrude starflite 100s, i know the gear case is bigger but can it still be used on my 90. opinions are greatly appreciated.

 

[yorab]

Re: Parts interchange

I can't answer your question because I'm not sure. However, you could do some preliminary research by going to marineengine.com and searching through the online parts diagrams for those two motors and determining how close those two lower units are. Some things to look for would be that the driveshafts for both models have the same type/number of splines. Also, obviously, the bolt holes must line up between the lower unit and the exhaust housing. Also, the water pipes must be the proper length. Another thing to look for is the gear ratios. Perhaps they were different between those years and using the bigger lower unit may put a heavy load on your engine. These are just some ideas to start with.

If you have no forward or reverse, then it could be something as simple as broken or exposed shift wires in the gear case. Have you tested the gearcase that you have to determine why it's not working properly?

 

[IMPERIAL16]

Re: Parts interchange

i totally understand where you are coming from. that does sound difficult about knowing if, like you said , all those areas do match up. i have been talking to a guy local here that deals wtih nothing but these older motors. he told me to test the lower unit without running the engine itself just push the forward button and test the prop by spinning it the direction it is suppose to go and shouldnt go the other way while spinning it well that isnt the case for both forward and reverse. im leaning towards it could be the coils inside the gearcase. cause im guessing that you should be able to hear the gears engage when you push the buttons, but they dont. and the wiring looks fine to me that i know of. but if there is other options just let me know

 

[Willyclay]

Re: Parts interchange

my ? is what are the yrs and hp that i can interchane the lower unit from i bought a 1968 evinrude starflite 100s, i know the gear case is bigger but can it still be used on my 90. opinions are greatly appreciated.

First my disclaimer, I am an old geezer who has been fooling with outboards well before your 1964 motor was new BUT have never worked a single day as a professional in the marine industry. That said, I currently have a 1968 Johnson 100HP with the large gearcase and previously had a 1962 Johnson 75HP with the electric-shift gearcase. You question got me curious, so I spent a little time looking at OEM part numbers at the link below and believe it may be possible but you will need to do some additional p/n comparisons yourself before trying the swap.

http://www.marineengine.com/parts/parts.php

I learned that the gasket (#0305312) between the exhaust housing and the gearcase is the same for your motors and my motors which to me is a pretty good indication they will bolt up. However, water tubes and driveshafts might be different issues for you to investigate. FYI, OMC used FOUR different gearcases for the 1958-1968 V4 series of motors with the 1968 version requiring an "adapter" that the others do not. I also think the 1968 version was utilized on the OMC I/O drives of the day in case you are looking for parts/props. The original gearcase used on the "Fat" 50HP motors was referred to as "heavy Duty" and was manual-shift. You are familiar with the electric-shift version. However, you may want to checkout the "standard gearcase" that was widely used in this series and is a "manual-shift" unit. Retro-fitting it may be possible also AND it was a little smaller in an attempt by OMC to achieve higher speeds. Good luck with that great old motor and let us know what you do!

 

[Daviet]

Re: Parts interchange

You will not hear any gears engage in the lower unit, it uses springs and coils, no noise at all. You need to do some electrical checks and see what's wrong.

 

[IMPERIAL16]

Re: Parts interchange

wel i have an update on my motor. i did not change out the lower unit from my 100s. what i did is swapped out the whole shifter unit up near the captain seat with the switch from the 100s.(same as 90s) before when i would run the engine the gears wouldnt shift into fwd or rvs. so i swapped out those components on sunday and it was a sure thing. the switch was bad. ran the engine and put it into fwd and the motor bogged down a little and went back to see and the prop was spinning like a son of a gun. and it also did in reverse. now the next thing i have to see how it does in the water.

now when its in the water and pops out of gear goin on plane like it did before all this happened, could the continuity of the switch throw the gears out? i just want to prepare myself. let me know what you guys think

 

[IMPERIAL16]

Re: Parts interchange

wel i have an update on my motor. i did not change out the lower unit from my 100s. what i did is swapped out the whole shifter unit up near the captain seat with the switch from the 100s.(same as 90s) before when i would run the engine the gears wouldnt shift into fwd or rvs. so i swapped out those components on sunday and it was a sure thing. the switch was bad. ran the engine and put it into fwd and the motor bogged down a little and went back to see and the prop was spinning like a son of a gun. and it also did in reverse. now the next thing i have to see how it does in the water.

now when its in the water and pops out of gear goin on plane like it did before all this happened, could the continuity of the switch throw the gears out? i just want to prepare myself. let me know what you guys think

???

 

[Willyclay]

Re: Parts interchange

now when its in the water and pops out of gear goin on plane like it did before all this happened, could the continuity of the switch throw the gears out? i just want to prepare myself. let me know what you guys think

I'm going to say "yes" that loss of continuity (12V) would cause your motor to pop out of gear especially under load while on plane. The clutch springs in the gearcase are fairly light and serve only to keep the gears separated until one of the solenoids is energized. However, it could also be a slipping prop clutch hub that will let go under load but look okay at idle whether it's in fwd or rev. BTDT with my electric shift. You need to do some further checking and eliminate some of the possibilities. Good luck!