tooth count on gears

[isleno1]

Does anyone know how to identify a ratio for a drive by tooth count or any other ways?
I need a ratio of 2.18 to 1 lower end of a VolvoPenta, it goes on a Volvo 3.0 in line 4 cyl. I'm trying to buy a lower unit for it. It seems that some people when dealing in these parts only go by the count of teeth and/or other methods that I'm not familiar with. Also, since the ratio is determined in the lower unit on this particular drive, it is best I get a count on the teeth to know what I need. So, does anyone know what the tooth count would be for this drive?

 

[billbayliner]

Re: tooth count on gears

I'm sure that Don has a simple explanation on how to find this out.

Do you have both components now?
This is an over-all ratio, so as long as the upper and lower are still connected to each other, you could essentially turn the main drive gear and count the reduction.
Lock the sliding sleeve to one gear cup.
Once you begin rotating the main gear, do not let up......... keep friction on the prop shaft.
If the sliding sleeve and cup loose contact, you'll need to start over.
Do this several times and take an average.
The next ratio would be enough different that I doubt you could make a mistake.