Transmission reduction ration

[Balwin60]

Hello everybody, I have a 1991 Vision 32. love the boat. I am interested in a maxprop. They are asking me for a transmission reduction for the Yanmar 3GM diesel. Does anyone know this information or where to look?
Thanks

 

[Bill Roosa]

Google???
They want to know so they can set the prop pitch up for you. When you take the old one off it will have the prop pitch stamped on it and you can set it yourself.
Think this is one of those "Assume command" moments with the sales person.

 

[RichH]

The gear ratio should be stamped on an attached ID plate -- ON the transmission 'cover plate' that includes the transmission 'fill plug/dipstick'

The ID plate will have:
Model Number
Serial Number
ID of the lubrication fluid to be used
Gear Ratio

 

[Balwin60]

Thanks for the help guys.

 

[Claude L.-Auger]

The plate on the tranny will tell you. On my Yanmar 3GM30F the Kanzaki transmission ratio is 2.61/1. My fixed 3-blade prop is RH 15 X11 although some have reported 15 X13. As Bill said your prop will also be stamped.

 

[Dave Groshong]

It's usually 2.62:1

 

[Claude L.-Auger]

It's usually 2.62:1

Dave, OP stated he has a 3GM engine. According to info on page 10-2 of Yanmar Engine manual, tranny on most 3GM is KM3-a (later replaced by KM3-P) and the ratio is 2.61. The 1GM and 2GM however share tranny KM2-C and they do have a 2.62 ratio.