Trying to figure out what drive I have

[dn010]

Got a new old boat and need to do some repairs and overhauls on er. I removed the drive, opened the top cover and the oil is nasty blackish color with spots of water here and there. There's nothing rusted so I guess that's a good thing. Nonetheless, I know it's an Alpha drive, but not sure of anything else. There are no decals or anything, just a really poor paint job that someone did to it. All I have is the number A689539 - there is no 0 before the A.... I'm basically trying to figure out what drive and what ratio I have. It was connected to a 350 (so I know I need 1.5:1), but I'm not sure this drive is correct. Boat is a 1986 Larson, any info would be great. I did look through the downloadable serial number PDF's, but I'm just not seeing it. Thanks for any help!

 

[Don S]

Re: Trying to figure out what drive I have

It's a 1986 Alpha I with a 1.50 gear ratio. Model #01509016

 

[dn010]

Re: Trying to figure out what drive I have

Thank you for the reply, glad it is correct to the boat. Now, what would cause a tooth to break off the upper driven gear? It's a pretty big chunk, and I haven't taken the gears out yet - that's tomorrow. Is it possible for this chunk to make it to the lower portion and trash the forward gears etc? I'm hoping to get away with just rebuilding the drive shaft housing! Thanks again

 

[Bt Doctur]

Re: Trying to figure out what drive I have

Hitting something with the prop will chip a gear.

 

[Don S]

Re: Trying to figure out what drive I have

Metal fatigue can also cause a gear to fail.
The only way to know about the lower is to open it up and inspect the gears and bearings.

You do realize you need special tool to replace the gears in the upper. You have to set gear heights and preloads.

 

[dn010]

Re: Trying to figure out what drive I have

Thanks for the replies. Yes, I realized this the first time I rebuilt a drive. I can do the upper, but not the lower...

After thinking about it, if the upper isn't in good shape - I'd imagine the lower isn't too far off. It looks like it was hardly maintained... For piece of mind-especially when being miles offshore, think I'll dump this one. Thanks guys.