Is 1.50:1 the same as 17:21 upper gear ratio for OMC

kilapapipa

Cadet
Joined
Jul 18, 2009
Messages
19
I know I have a 17:21 upper gear ratio off a factory 305 from 1983. My sticker is gone from the top and I found one that says 1.50:1 on the sticker. Are these the same?
 

cr2k

Captain
Joined
Mar 19, 2009
Messages
3,730
Re: Is 1.50:1 the same as 17:21 upper gear ratio for OMC

As far as I know no one ever used that format for a gear ratio.

Sounds more like a big prop.

Even if you divided it out it would not be the same.
 

180shabah

Rear Admiral
Joined
Mar 26, 2005
Messages
4,995
Re: Is 1.50:1 the same as 17:21 upper gear ratio for OMC

cr2k - there are two different gear sets, one in the upper, one in the lower. The combined reduction will give you the final ratio.
 

rs2k

Chief Petty Officer
Joined
Aug 2, 2008
Messages
486
Re: Is 1.50:1 the same as 17:21 upper gear ratio for OMC

The correct gear ratio for the top is 21:17 for the 305. I can't remember what the correct gear ratio for all V8 800 drive lower units is 14:26. This gives you a total of .67 which gives you an overall ratio of 1.50:1.
 

kilapapipa

Cadet
Joined
Jul 18, 2009
Messages
19
Re: Is 1.50:1 the same as 17:21 upper gear ratio for OMC

The correct gear ratio for the top is 21:17 for the 305. I can't remember what the correct gear ratio for all V8 800 drive lower units is 14:26. This gives you a total of .67 which gives you an overall ratio of 1.50:1.

Just what I needed to know. I bought a used drive off a guy who said it came of a V-6. The sticker on the top said 1.50:1 and it had the same prop on it as mine. It also had close to the same model and serial number as mine. I now have it mounted and ready for a test.

Funny side note, we tried the steering and it was backwards. Thanks to some research on this site I found out about 2 diff. worm gears. I elected to switch my steering box 180* instead and we are ready to go.
 
Top