OMC upper gearcase drive shafts

[SnapperBlue]

I've got a 1973 SeaSwirl with an OMC outdrive. The male end of the waterpump shaft is trashed and worse is the female end of the drive shaft that sits on top of it.

I bought a used upper gearbox off Craigslist and it turns out it has the same problem! (lesson learned). I'm having trouble finding a replacement upper drive shaft (aka pinion shaft). The OMC part number is 907730. There are a few on the internet, but they're hundreds of dollars.

I've seen other shafts on the internet that cost less and look identical in the photo, but they're not listed as fitting my gearbox series. I thought all low-profile OMC's had the same shaft up 'til 1977.

Anybody got a clue on a cross reference for this part, or know a mechanic with the answer?

Thanks!

[Boat Doc']

Originally Posted by SnapperBlue

I've got a 1973 SeaSwirl with an OMC outdrive. The male end of the waterpump shaft is trashed and worse is the female end of the drive shaft that sits on top of it.

I bought a used upper gearbox off Craigslist and it turns out it has the same problem! (lesson learned). I'm having trouble finding a replacement upper drive shaft (aka pinion shaft). The OMC part number is 907730. There are a few on the internet, but they're hundreds of dollars.

I've seen other shafts on the internet that cost less and look identical in the photo, but they're not listed as fitting my gearbox series. I thought all low-profile OMC's had the same shaft up 'til 1977.

Anybody got a clue on a cross reference for this part, or know a mechanic with the answer?

Thanks!

Try Steve Ryan at Ryans Marine service 503-282-8807. If he can't help he will know someone who can

[Orca]

Looks like '73/'74 were the only years for the low profile, non centering cone drive shafts. This type of shaft is for '75 - '85 since it uses the centering cone - http://bpi.ebasicpower.com/mm5/merch...ory_Code=OMC3G , note the smooth area below the threads and above the splines.

Looked at the GLM catalog, and they don't make a replacement for that shaft. Doesn't look like Sierra does either. If all else fails, you might call GLM and/or Sierra and see if they have a solution.

[Waterfish]

Sportsman Marine in Salem.

[SnapperBlue]

Originally Posted by Orca

Looks like '73/'74 were the only years for the low profile, non centering cone drive shafts. This type of shaft is for '75 - '85 since it uses the centering cone - http://bpi.ebasicpower.com/mm5/merch...ory_Code=OMC3G , note the smooth area below the threads and above the splines.

Looked at the GLM catalog, and they don't make a replacement for that shaft. Doesn't look like Sierra does either. If all else fails, you might call GLM and/or Sierra and see if they have a solution.

[SnapperBlue]

Thanks for pointing out the difference between the two shafts. I never noticed the smooth area on the pictures I saw on the web.

Interestingly, I've got two gearboxes with the same non-centering cone shaft and they have different pinion gears.

[SnapperBlue]

Good News! I just spoke with Steve at Ryan's Marine. He uses the newer centering cone shaft on all of those gearboxes. He said I just have to add the centering cone and the shaft will come up flush with the locknut.