What's my gear ratio?

imported_boatin clan

Seaman Apprentice
Joined
Sep 13, 2006
Messages
45
I have a 1988 Alpha I drive, ser # 0B995741. How can I tell what the factory gear ratio was (is) without pulling the lower unit?
 

imported_boatin clan

Seaman Apprentice
Joined
Sep 13, 2006
Messages
45
Re: What's my gear ratio?

205 HP according to Merc, but 230 according to previous owner. The engine is a Mercruiser 4.3LX (4 bbl). Not sure if any and what mods may have been made.
 

Laddies

Banned
Joined
Sep 10, 2004
Messages
12,218
Re: What's my gear ratio?

17 - 19 upper gears before serial number K999999 gives a total ratio of 1.84 to 1 and after that a total ratio of 1.81 to 1 because of differant lower unit gear ratio.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: What's my gear ratio?

Look at the picture below. Not only are the numbers on the decal, but they are stamped on the upper casting under the decal in the same approx. possition. That will tell you what it was when it was new. But if anyone has rebuilt the drive or used different gears in that housing, all bets are off. And, it is an 88 drive.

Alpha%20SN,%20ratio%20stamps.png
 
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