Gear ratio, questions and how to figure it out..

[budsbud66]

ive been trying out a prop calculator and im wondering what gear ratio my motor really is.. <br /><br />is there way to figure out the gear ratio? <br /><br />or does anyone know where to find the info.<br /><br />1984 65hp commercial. ive heard the gear ratio on this motor is different.. <br /><br />does the whole lower unit need to be changed to switch gear ratios? on my snowmobile its just little sprockets and you can swap them in a half hour.<br /><br />Also what kinda performance gains and changes can i get by changing the gear ratio?<br /><br />thanks

 

[ezeke]

Re: Gear ratio, questions and how to figure it out..

The gear ratio is listed in the J/E model specific Service Manual in the "Specifications" section. <br /><br />It may also be listed in the Owner's Manual under "Specifications".

 

[Dhadley]

Re: Gear ratio, questions and how to figure it out..

Since it may be in question which gearcase you actually have the easiest thing to do is count the turns. <br /><br />Mark the flywheel and propshaft. Turn the flywheel clockwise until the propshaft turns 10 times. Then the number of flywheel turns, divided by 10, will tell you what you have. You can stop after the propshaft has turned once but 10 times is more accurate.<br /><br />IE -- if the flywheel has turned 24.16 times, your gear ratio is 2.416:1.

 

[budsbud66]

Re: Gear ratio, questions and how to figure it out..

thats the equation i was looking for..<br /><br />what about switching gear ratio's im guessing its not easy to do on a lower unit? or would it be pointless?

 

[Dhadley]

Re: Gear ratio, questions and how to figure it out..

We do it with race boats but at the rpm youre talking about it may not be worth it. What gear set are you thinking about goint to?

 

[budsbud66]

Re: Gear ratio, questions and how to figure it out..

well i thought the commercial motor had a real poor gear ratio. so i thought if there was an easy fix i would do it.. i really dont know what the gear ratio is for on an outboard motor.. i guess the higher the gear ratio, the more torque on the prop?