lower unit advise ?

[Paul Labrecque]

I have a 100hp mariner 1994 and it runs like a 2+2 but it runs good outside of that. the skeg is busted off and not really repairable,it doesn't leak and I've been running it like it is . I found another lower unit for a great deal from a 75hp 3jaw like my 100 but the gear ratios are different 2.07 on the 100 and 2.31 on the 75 . my question is, should I bother to swap out the gears ? or just go with a higher pitch prop ? the gear case is in great condition . I have three props 21P I'm thinking I need to go to a 25P ?

Paul

 

[flyingscott]

Swap the gears and your motor is a 2+2.

 

[Chris1956]

Why is the current gearcase not repairable? You used to be able to buy new complete skegs that could be welded to the gearcase.

 

[jimmbo]

If the driveshaft splines are the same, I would just install the unit, and go up one pitch on the prop to a 23. The rpms will probably be with about 100 from where you were with the old case-prop

Or... get a Skeg welded on the old unit.

 

[Faztbullet]

If your is a 6jaw the powerhead will need pulled and old 3 jaw linkage installed as throw is different.

 

[Paul Labrecque]

ok so here's the deal ,welding a new skeg on would be iffy it broke off and one of the studs is exposed nothing left to weld to the lower unit from the 75 will bolt right on its a 3 jaw, same as my 100. I think that is what I'm going to end up doing.. swaping the gears from one case to another requires some special merc tools to get it shimmed up right which I don't have. if my calculations are right I'm going to need a 25P prop with the 2.31

I might try to weld up the old case but I don't have much hope for it .