Lower Unit compatability

[bryancx94]

My motor is a 94 mariner 90HP3cyc, 2cycle I want to connect a lower unit from a 99 mercury 4 stroke bigfoot. All the bolt holes line up, size is the same, shaft is the same, everything looks the same just... as an added precaution I wanted to check on here to make sure its the right thing to do or if there is something else I should check.

 

[phatmanmike]

Re: Lower Unit compatability

check the driveshaft ends, make sure its the same length and same splines.

gearratio may be different

try it and find out.

be like lewis and clark

 

[WillyBWright]

Re: Lower Unit compatability

Won't fit!

2-strokes use Mercury splines. 4-strokes use Yamaha splines. The splines on the 4-stroke are finer and much longer, and Metric! You might be able to swap driveshafts if you are able to do the shimming procedure. Ratio mayt be different, but usually compensatable with prop pitch.

What is a 90 BigFoot? Never heard of such a thing. It would have to have a V-6 gearcase and I doubt they'd do that.

 

[WillyBWright]

Re: Lower Unit compatability

Sorry, doubled-up somehow.

 

[bryancx94]

Re: Lower Unit compatability

The lower unit for sale is off of a 1999 Mercury 50hp 4 stroke. If i use my driveshaft, and shim it properly do you think i will have any issues?