Volvo Penta SX-M Gear Ratios?

[ESGWheel]

Any way to ID the gear ratios in this unit without taking it apart? 2005 Larson 228 LXi with a VP 5.0 GXi-E and a SX-M Stern Drive. As you can see from the picture the key sticker is missing. The original owner that I bought the boat from said they did not change any portion of the outdrive. In talking with a company that rebuilds outdrives, they said my overall ratio is 1.60 based on my engine serial no. Looking to validate that as well as the individual ratios of the upper and lower units. Reason: I plan on buying used units and spending the time to rebuild those and replace them lower first, then upper. I have looked for any stamping and plates on the outdrive and have not seen any, but perhaps I am not looking in the right places.

Thanks for any tips / help.

 

[Scott06]

Any way to ID the gear ratios in this unit without taking it apart? 2005 Larson 228 LXi with a VP 5.0 GXi-E and a SX-M Stern Drive. As you can see from the picture the key sticker is missing. The original owner that I bought the boat from said they did not change any portion of the outdrive. In talking with a company that rebuilds outdrives, they said my overall ratio is 1.60 based on my engine serial no. Looking to validate that as well as the individual ratios of the upper and lower units. Reason: I plan on buying used units and spending the time to rebuild those and replace them lower first, then upper. I have looked for any stamping and plates on the outdrive and have not seen any, but perhaps I am not looking in the right places.

Thanks for any tips / help.

@muc or @Scott Danforth may know

 

[Scott Danforth]

from my google fu

Within the 22/23 Upper, you can choose from five different gear ratios. Those are 1.43, 1.51, 1.60, 1.66 and 1.85. As for the Volvo SXM 21/26 upper, there are 1.79, 1.97 and 2.18 ratios

 

[muc]

It was Commissioned in 2005 with a 1.60
There are two ways to be sure what you have. Disassemble and count the teeth or turn the input shaft and count the revolutions of the prop shaft.

I would recommend that you go thru the upper and lower at the same time. Volvo has a much better gear lube circulation system than MerCruiser, so any bad stuff left in the half you didn’t do will contaminate the half you just did.

 

[ESGWheel]

Following the ‘all at once suggestion’ if bought a complete used outdrive to rebuild that has an overall 1.60 does it matter if I get a:
* 22/23 with a 1.65 (for total of 1.158 which I assume they round up to 1.60)
Or
* 21/26 with a 1.97 (for total of 1.159 which I assume they round up to 1.60)

Thanks for the help and advice.

 

[ESGWheel]

Scott,
I think I misunderstood about the ratios. I was thinking that the numbers provided where the upper ratio (provided by gear teeth) and the other numbers were the available lower unit ratios, hence why I multiplied.

I now think that the listed ratio numbers are the FINAL ratios available for a particular upper. Is that correct?

Still learning about SDs.

Thanks.