Converting a SM-M drive to duo prop - ratios?

[gg1919]

I'm looking to convert my single prop SX drive to a duo prop. I have a 2006 Four Winns H240 w/ a VP 5.7GI. I've read places that it's only the lower unit that needs to be changed. My drive has a tag on it that says it's a 1.51 ratio, but the duo prop drives appear to be 1.95 for my boat.

Ideally I want to swap lower units with someone and have both drives functional. If I swap my lower to a drive w/ a 1.95 ratio will both drives work?

I know there's folks on here that have done these swaps. Any information you can give me would be appreciated. I have the serial # info from my SX drive as well if it helps, but I'm waiting to get that info from the DP drive.

Thanks in advance

 

[Scott Danforth]

welcome aboard.

only the lower gets changed. the gear ratio is in the lower

you wont be able to swap someone your SP lower for a DP as once you go duo-prop, you never go back to a single. you will need to buy a DP lower.

 

[gg1919]

Thanks for the welcome aboard! I appreciate your response! I may be able to get someone to swap though... I found someone selling an older boat that's in really good shape mechanically and offered them the swap plus cash. I think it's a good deal all for both of us. The other party gets cash toward their sale plus a SX drive in excellent shape and a nice 4 blade SS prop, I get the duo-prop (and then apparently never ever go back )

So, theoretically that swap would work for both parties gear wise? They're both SBC V8s. Are there seals or other parts needed for this swap, or is it just drain them, drop the 6 bolts and swap them over?

Again, I appreciate the knowledge.

 

[gg1919]

Also if I had both serial #s is there a way to make sure 100% that the uppers and lowers will work?

 

[Scott Danforth]

you need seals. there were changes along the way, so you have to check the parts for both serial numbers. best to get the same vintage.