1983 75 hp Rude prop concern (new prop)

[redneck joe]

Just double checked to make sure I ordered the correct prop and I did - even went with a OEM. Got it on and there is a slight rub when turning - just enough resistance to not allow a full spin if I just flicked it. Appears to be rubbing the motor where they join. Put the old back on and no rubbing (no part # so not an EOM). The OEM is about a 16th of an inch wider by my measuring. I've spun it about 75 times and it appears to not even rubbing the new prop paint off, just has a little color to it. Can not see any discernable variation on the lower unit casing. I did have to use different spacers - the first one on whatever its called is much thinner than the one that was on there and with the old one on the outer spacer (the one with teeth) didn't grab. I've been boating 40 years and this is my first time pulling a prop aout.



Thoughts?

 

[Texasmark]

Did the old prop have a rubber slip hub and the new a replaceable plastic with a brass insert? Usually plastic uses a different thrust washer....the washer the prop pushes against. When you get it right, it won't rub and you will have several threads of the prop shaft sticking out from the nut after torqueing....55 ft lbs is pretty close if not right on.

 

[redneck joe]

New one is rubber

 

[Texasmark]

Well you will need a different thrust washer. I bought several props from Iboats and the one I bought with a plastic hub (Hustler alum) had the hub and thrust washer displayed on the same page as the prop when you were on the page where you bought it so that you could get the right parts to mount your new prop. Might have a look.

In short, what fit my rubber hub props didn't fit the plastic.

 

[redneck joe]

I did buy new plus the prop came with which is what i used. Is the peop supposed to be inside the lower unit casing a touch ? The old one was. Ir does it stay outside it? Big boat is in the shop so camt check against a mercruiser

 

[Texasmark]

Depends on the prop. some, like thick material alum have an offset, or notch of about 1/4" back along the barrel where it slips up in the housing. Thin SS props usually don't have it as they sit inside, like if the housing is a Merc mid range the LU housing is 14 1/4 wide but the prop is 14. and slips up into it slightly. You can't see light to the other side at the prop LU interface.