Prop Shaft Identification Help

[nj-boatbuilder57]

Really would like it for a 35DE11 (or12) from ’59, if you have it.

If you do, could you e-mail the whole document?

Still, I see that in ’58 Gale was using the 23-spline shaft. Very interesting….

[frankr]

nj-boatbuilder57 wrote:

Really would like it for a 35DE11 (or12) from ’59, if you have it.

If you do, could you e-mail the whole document?

Still, I see that in ’58 Gale was using the 23-spline shaft. Very interesting….

You have a PM.

[nj-boatbuilder57]

received & replied….thank you!

[nj-boatbuilder57]

OK…I’ve done a ton of research, cris-crossed a ton of part numbers, and reached some conclusions:

1.) In 1958, across the 25-35HP offerings, OMC made changes to their gear sets. The housing didn’t change, but the shaft did: 1.) prop-nut attachment and 2.) added a spline, going from 22 to 23. The dog changed too, as did the dog cradle.

2.) the gears changed, but how & why remains a mystery to me. The pinion gear changed in part number, but the actual gear remained the same. The forward & reverse gears changed, but…as stated…not sure how. The pinion is still 12-tooth and the drive gears remain at 21-tooth, so the gear ratios remain the same.

3.) All of the bearings, rings, seals & bushings remain the same from 57 through 59 (and maybe further, but I only researched to 59)

I have to suspect that the gears & dog were all “improved” in some fashion….and certainly more splines provide better engagement (though only one spline can’t make THAT much of a difference, can it?)

I’ve concluded that my ’57 housing could accept the 23-spline shaft, but I’d have to replace the drive gears, dog & cradle as well…and that’s a tall climb just to achieve commonality of prop nuts. The only reason to do so is if the later gear/dog/shaft arrangement is in some fashion superior to the ’57 set. But how many tens of thousands of hours have been run on stock 57 engines without issue?

My decision….unless there’s a true & provable proof that the 58-59 gears are superior…I’m going to reassemble the 57 in its stock configuration. Anybody need a 23-spline shaft? 🙂

[frankr]

I can’t explain the “why”. But they did a similar change in the mid-range motors like 15-18hp etc., back around that era. Look-alike prop shaft splines that don’t interchange. I have some shafts and dogs that I don’t know what they fit.

[dave-bernard]

ied to make stuff that would last longer and this was the way to keep from interchanging the old and new sets????

[opposedtwin]

To give my opinion/recommendation on swapping the shaft, I would not do it.
I stumbled onto this issue a few years back when I acquired a 58 johnson after having owned/run a number of 50s era RD models. I ran into it when trying to fit a 57 prop onto 58 shaft. Had to source a 58 prop nut.

You are more adventurous than I, as I would never have tried to swap shafts. Still, you (and we) learned something, and that ain’t all bad!

I’d keep the gear cases separate. They swap out so just keep the prop nuts with the appropriate case. Who knows, you may stumble into an earlier model RD/Bigtwin that needs that case. I stumble into them every time I go into my garage!😀

Happy motoring!
Scott

EDIT: I believe Dave is onto something there. Seems like many times with OMC, while it seems to us that a change was pointless, it made perfect sense from a maintenance or parts management standpoint.

• This reply was modified 4 years, 4 months ago by opposedtwin.

[nj-boatbuilder57]

I’m re-sealing the gearcase today…100% original configuration. This was one of those “looks good on paper” ideas that just didn’t work out that way!

I learned an awful lot in the process, though….so that’s a bonus, right?

• This reply was modified 4 years, 4 months ago by nj-boatbuilder57.

[Author]

Posts