Question regarding prop shaft

[Dunromin]

1984 OMC 4L sterndrive rebuild

Newbie question, I have removed the prop shaft assembly from the lower gear case, and I can see how water is kept out of the gear case by a series of O rings and cup seals.
Since this came to me almost totally disassembled, I loosely place all the components on the shaft to check nothing missing, and the only thing not there is part #384977, propeller bushing.
I'm guessing this fitted inside the original prop, and since mine now has a prop with a moulded center it is no longer needed. Am I correct?
Also, a small section of the outer prop shaft behind the prop is exposed to water, I can see no rust on the shaft, and I would have expected some if it was not protected. Is this right?

 

[Texasmark]

No idea really but usually the prop shaft has a thrust washer for the prop to push against on the shaft, tapered for a tight fit on Merc. engines and then the prop (if pressed hub no accessories) and then some sort of retainer. On removable hubs, you have the hub and the prop shell. On Merc. there is a locking washer with detents for the next item the locking ring with tabs that you push down into the detents and finally the locking (nylon insert) prop nut torqued to something like 55 ft-lbs. On some OMCs there is a "drive pin that goes through a hole in the prop shaft and rear of the prop and a cap over that with a cotter pin to hold the cap in place. I don't think this type has a thrust washer...relies on the pin to maintain distance between prop and lower unit housing, seals and bearings.

 

[Dunromin]

No idea really but usually the prop shaft has a thrust washer for the prop to push against on the shaft, tapered for a tight fit on Merc. engines and then the prop (if pressed hub no accessories) and then some sort of retainer. On removable hubs, you have the hub and the prop shell. On Merc. there is a locking washer with detents for the next item the locking ring with tabs that you push down into the detents and finally the locking (nylon insert) prop nut torqued to something like 55 ft-lbs. On some OMCs there is a "drive pin that goes through a hole in the prop shaft and rear of the prop and a cap over that with a cotter pin to hold the cap in place. I don't think this type has a thrust washer...relies on the pin to maintain distance between prop and lower unit housing, seals and bearings.

I think the rear of the shaft is chrome plated. It's the only thing to explain the lack of rust.

 

[Texasmark]

You can bet the drive line...prop shaft and drive shaft from engine to lower unit are solid SS.

 

[Dunromin]

You can bet the drive line...prop shaft and drive shaft from engine to lower unit are solid SS.

I was kicking myself for not thinking of SS, but when I checked it with a magnet, it was magnetic, so I guess, back to chrome plated steel. I understand your description of the purpose of the thrust washer, which is among the parts I got, thanks for the explanation.

 

[Texasmark]

I was kicking myself for not thinking of SS, but when I checked it with a magnet, it was magnetic, so I guess, back to chrome plated steel. I understand your description of the purpose of the thrust washer, which is among the parts I got, thanks for the explanation.

SS comes in all flavors and mixes. If any iron is in the steel which is normally the case on OB shafts with Chrome and Nickel, you will attract a magnet. Also on some SS props you will notice corrosion as I have seen and discussions are all over about combating it. OMCs first SS prop was the SST, a SS prop with black Teflon coating and a Brass/Bronze deflector ring. The Teflon was to prevent corrosion.