gear ratio in lower unit

[boatFam]

We unfortunately lost an argument with a shallow rock over the past weekend and now have a hole in the leading edge of the skeg in our sterndrive. I will have to replace the lower unit on my 1993 Wellcraft Scarab Sprint and have determined it is a Alpha One Gen Two sterndrive. I have done a bunch of research and cannot find out how to determine what the lower end gear ratio is. There is no decal or sticker or imprint on the drive to tell me this.

Can anybody tell me how to find out what the gear ratio is, so when looking at replacements I can match it up correctly? BTW, the engine is a 4 cyl. 140 horse Merc.

Thanks in advance.

 

[jtybt]

Re: gear ratio in lower unit

Download the manual from the "adults only" section. It has the gear ratios for the drives.

 

[boatFam]

Re: gear ratio in lower unit

I did download the manual before I made the post.. but, unless I am reading it wrong, the gear ratio they make reference to is that gear drive in the upper unit.. I understand their is also a gear drive in the lower unit as well for the prop shaft and its corresponding gear. Am I reading this wrong?

Thanks

 

[wca_tim]

Re: gear ratio in lower unit

the gear ratio in the lower half of the merc drives is the same (or so close it doesn't matter). the upper is what is different.

the gear you need for the upper half is 1.98.

 

[boatFam]

Re: gear ratio in lower unit

Excellent.. thanks alot for the help...Much appreciated

 

[wca_tim]

Re: gear ratio in lower unit

also... make sure consistent between generation one / two. they aren't interchangable.

and finally, sei makes an aftermarket drive that works well for a very reasonable amount of money. you can buy just a lower or just an upper depending on what you need and it comes with a 3 year warranty. worth checking into. last couple of times I've needed one that's what I did and was very pleased with the result.