Small gearcase to large gearcase conversion

[Kevodaniel]

I have 99 40hp johnson with small gearcase lower and was wondering if I could put a large gearcase on it for more prop selection if not I need a small gearcase lower cuz mine is toast

[omcstratos]

you're going backwards if you are wanting speed. The nitro case is already 3.5inch exhaust hub diameter. Also I believe that the length of the midsection where both the face of the gearcase and the face of the midsection meet are not the same on the small and large gearcase.

[Kevodaniel]

you're going backwards if you are wanting speed. The nitro case is already 3.5inch exhaust hub diameter. Also I believe that the length of the midsection where both the face of the gearcase and the face of the midsection meet are not the same on the small and large gearcase.

I know they made some 50 hp commercial motors that have large gearcase but I don't know if mid section is the same

[LittleCharger]

I know they made some 50 hp commercial motors that have large gearcase but I don't know if mid section is the same

The large gear case will bolt right up, but as omcstratos said you'd be going backwards in terms of speed and handling by going to the large case