Slipped pin drive hub old 80hp rude

[a70eliminator]

Hi, I just experienced hubslippage, I could get up onto plane then all at once 100% slip, just like in neutral, I slowly cruised back into the docks and put my spare prop on and now it's all good again.
Here's my question:
Earlier the season I was raising height of my outboard (the cav plate was 2" below) I raised it 3" and got 100% prop slippage on plane, then droped down another inch and still got slippage, I ended up right back where I started with cav. plate about 2" below keel and all was good again. Could raising the engine have caused the prop to operate that much more efficient to where the hub would slip? And now of course the prop hub finally gave out compltely, could it have been slipping the whole time once I would get the motor height right? yet operate ok with cav plate 2" below the keel?
Was pin drive the right terminology? Sheer pin retained by prop cone and cotter pin.

 

[steelespike]

Re: Slipped pin drive hub old 80hp rude

Your hub failure is just that a hub failure. Don't read too much into it.
What your experiencing is ventilation not slippage. Slip is used to rate prop efficiency. I have a feeling your props are either a little beatup or really basic.
The Antivent plate (cavitation is a different problem)even with the bottom is considered a starting point.Most setups end up about an inch above.
You may need a prop with some cup.Turning point Hustler props work well and deliver close to stainless performance at aluminum prices.
I just realized I think you have the old style 2 piece gearcase you won't be able to raise it as high.Again prop selection may help.Unfortunately prop selection will be limited.
You may be able to have a good prop shop add a little cup.

 

[a70eliminator]

Re: Slipped pin drive hub old 80hp rude

Let me re-phrase this, could the prop have gotten a better bite when I raised the engine (cav. plate even with keel) and spun an already weak hub, then lowering the engine back down cause such an inefficiency that the hub was hanging in there ok until now, I thought raising the motor was causing cavitation but now I'm thinking it may have been hub slippage the whole time. I guess I'll have to start experimenting with raising the motor again with this prop, the prop that slipped the hub was in excellent cosmetic shape never hit anything with it. I don't have a two piece case. it's a long shaft 80hp standard case 67 speedifour.

 

[steelespike]

Re: Slipped pin drive hub old 80hp rude

I would say your hub "spun" coincidently as you were testing.Changing the height reduces drag on the whole gearcase,Doesn't really affect prop grip except it might introduce more slip or ventilation.Perhaps the "weak" hub failed because you introduced faster throttle application when testing.Hubs do spin without any previous indication of a problem.With a good prop if you can get to about an inch above the bottom you could gain a couple of mph with no additional changes.