Force outdrive interchangeability

[Herbener]

Will a lower unit from a 1994 Force 120 work on a 1994 Force 90?

 

[The Force power]

No, the gear-ratio is different

 

[Herbener]

Thank you. Would it bolt up otherwise and then could I use a 13 pitch prop to compensate for the different ratio?

 

[The Force power]

I'm Sure on a '94 even if it did; I think they're too far out to compensate with a different pitch

read the sticky posts there's a lot of useful information in them

 

[Nordin]

Herbener.....the LUs are interchangeable and the gear ratio can be different.

Either is it 1,73:1 or 2:1 and you can check it by turning the drivshaft 1 turn and check how many turns the propshaft turn.
You can compensate by changing the prop pitch.

If you not change prop pitch the hole shot will be a little bit changed and also the RPM at WOT.

I have changed LU with different ratio and it works but the performance will change.
Since I do not care about super performance and never drive at WOT more them some minutes, I am pleased with it.

 

[jerryjerry05]

WRONG!!

Both gear ratios are the same.
In 1990 they started using the same gears in all the drives.
Before they introduced the 90/120 hp they used different gears,
then you'd make up the difference by changing props.

You can find a lot of info by checking the different lowers by looking at the parts diagrams.

They made a bunch of model #s for each year and hp.
But most changes are something simple like a bolt or a screw change.

 

[Herbener]

Thanks for the help. I think I'm going to buy it and try. I'll post what I ran into...

 

[The Force power]

Check the length of your & the one about to buy (drive-shaft) I'm not sure if the 120 came with a one & a two piece drive-shaft

 

[Nordin]

They started with two piece drivshaft with the 1990 year model.

 

[jerryjerry05]

They used the 2 piece from 90
They made it so the L Drive and the 20" and 25" wouldn't need a special lower unit and
it could use any 2 piece you could get.

 

[VivaLaMigra]

I'd try to find one of the newer lower's that uses Mercury propellers; the sort-of-leftover Chrysler prop is getting hard to find! They're around but finding your PITCH won't be as easy as going with a Merc prop.