What Is The End Play On An OMC Cobra Prop Shaft?

[DavidW2009]

The spec in question is for a 1987 OMC Cobra Standard with a 2.3L Ford (rubber band).

I just spent an hour searching the OMC manual and this forum and can't find that spec. (I may have missed it)

Putting a dial guage indicator on the end of the prop shaft, what should the end play be for normal operation?

I studied the exploded view and the parts on the shaft. The one part that may affect end play is the thrust washer between the prop and the shaft bearing. But, I need some help understanding this one.

Thanks.

 

[DavidW2009]

Re: What Is The End Play On An OMC Cobra Prop Shaft?

Rereading the OMC manual on prop installation, it says the thrust bushing seats on the taper of the prop shaft, the prop is installed, then the thrust washer and nut.

The prop nut is torqued to 70 - 80 ft. lbs. (forces the prop against the thrust bushing, which is seated on the prop shaft taper). So this means this has nothing to do with the prop shaft end play.

I have some end play in the prop shaft, but still can't find a spec on what's allowable, and what causes the end play (not talking about run-out).

I checked the end play on my Chrysler O/B and found a spec in the Clymer's manual.
The end play was .015" on the Chrysler. The Cobra has more, around .03". I don't know if that's enough to be concerned with.

I ran the Cobra today on muffs, putting it in forward and reverse up to 2K RPM. No noises, very smooth shifting and quiet.

 

[a70eliminator]

Re: What Is The End Play On An OMC Cobra Prop Shaft?

Unless the play is like all over the place I wouldn't even worry about it, a bent propshaft will cause excessive run out, anything over a .002 would be bad, mine has .012 runout, it's bent but will hold 10psi all night long, no vibrations with SS prop, aluminum prop reverberates quite a bit though at a certain rpm. I'm just going to keep running it.