bent my OMC propeller/output shaft

[F14CRAZY]

In deep, open water this weekend I hit some random submerged object and it seems that it bent the shaft that the propeller attaches to...the output shaft? This is my '85 non-Cobra unit paired with a 3.0L.

The propeller (stainless) seems to be fine, I don't see any new damage but if you spin it manually you can see it wobble a tiny bit. It isn't just the propeller wobbling but the end of the shaft including the nut and cotter pin wobbling. Also feel a little vibration in the steering.

I've got to fix it obviously. I'm assuming I have to remove the shaft from the lower unit and replace it unless my machinist can properly and precisely bend it back, but at any rate I'm betting i have to remove it. I haven't read the crappy Clymer manual yet...do I have to remove the entire sterndrive to remove the lower unit? Do I have to remove the lower unit at all or are there some bolts behind the prop?

Thanks guys.

 

[WizeOne]

Re: bent my OMC propeller/output shaft

Yes, you have to remove the outdrive. And now you know what no one ever bothers to tell you. DO NOT run a stainless steel prop on an OMC stringer outdrive. If you had whacked an aluminum prop we would not be having this conversation. Stainless does not yield, aluminum does.

 

[F14CRAZY]

Re: bent my OMC propeller/output shaft

hmm...it's what came with it. personally I wouldn't have spent the money on a stainless prop. Thanks for the advice though, and I agree, it would have bent the prop instead of the shaft (stainless prop would serve as the onboard spare)

 

[rs2k]

Re: bent my OMC propeller/output shaft

DO NOT run a stainless steel prop on an OMC stringer outdrive.

My cabin cruiser has twin OMC 800s and twin stainless steel props. Are the stringers' output shafts not as strong as other out drives? I know not to run SS props on the pin drive stringers, but what about the spline drive stringers?

 

[bamadave]

Re: bent my OMC propeller/output shaft

I think it applies for all outdrives. Stainless props transfers the impact to to shaft whereas the aluminum prop absorbs the impact through the damage to it. But for a hard enough strike, all bets are off.

 

[WizeOne]

Re: bent my OMC propeller/output shaft

My cabin cruiser has twin OMC 800s and twin stainless steel props. Are the stringers' output shafts not as strong as other out drives? I know not to run SS props on the pin drive stringers, but what about the spline drive stringers?

In certain respects they are just fine, strengthwize. BUT aside from the potential damage from impact, the OMC's are more sensitive to the extra weight of the stainless steel props, in two respects.

The extra weight increases the undampened vibration thru all points from the prop up thru the solid steel flywheel coupler. This greatly accelerates the spline wear on both the coupler and the somewhat less than desirably durable waterpump shaft.

The extra weight is is also harder on most earlier drives due to the flywheel effect when shifting into gear. Creates a much higher initial load to get the prop moving.

All that being said, how much advantage do you really get from stainless considering the direct cost, then add the cost of potential prop repair and bent prop shaft from impact damage. Over 34 years I have bent and or destroyed numerous aluminum props and never bent a prop shaft.