Force lower unit Swap

[bojango541]

Hello, I have a 1991 120 hp force outboard, im looking at a lower unit from a 1988 125 hp force. Everything looks the same except that where the water gets sucked in for cooling is in a different area. Will this still work for my motor?

 

[jerryjerry05]

Re: Force lower unit Swap

If the shaft is the same length.It should work.J

 

[Frank Acampora]

Re: Force lower unit Swap

The 1991 is a dual exhaust lower unit and uses a through hub exhaust prop. The 1988 lower unit is a single exhaust through the snout only. You can use either a closed hub or the prop you have now. If I remember correctly, the gear ratio is a little different between the two and you MAY notice a difference in performance. (slightly less speed with the 1988 lower.)

Physically, they both have the same bolt pattern, same splines, and same water tube location so as Jerry said, if the shaft length is the same, they will swap. The 88 will NOT have a speedometer pick-up hole in the front of it. The 1991 may have it. The 1991 has a two piece shaft so if the length is different, you can not swap shafts.

Personally, I prefer the earlier lower unit because the water pick-up is lower--it is on the side of the gearcase torpedo. I also prefer the arrangement of the top bearing in the 1988.

All things equal, is your present lower unit so trashed that it does not pay to try to fix it?

I do have a gear pak so if you are interested, send me a private message.

 

[bojango541]

Re: Force lower unit Swap

Thanks for the help Jerry, and Frank, you've helped me on a couple issues before.

One more question. Will a one piece shaft work with replacing a lower unit that has a two-piece shaft? Thanks, Nick

 

[Frank Acampora]

Re: Force lower unit Swap

As long as the shaft length is the same, that is, both from a twenty inch or twenty-five inch leg.