Stripped Threads in Prop Shaft Coupling

[jkenan]

In trying to get my prop shaft coupling removed, I was able to remove the retaining nut and washer with a little coaxing and penetrating oil. But when I screwed down the three 2" bolts to force the coupling off, it wouldn't budge. With more penetrating oil and some more gentle coaxing, I felt one of the screws give as I was tightening it down, and realized the threads had stripped (either on the screw or in the coupling). It turns freely now, but won't come out.

I am thinking of buying a three pronged 3" gear puller, and pulling off the coupling with that, and then drilling out the stipped screw and redressing the threads in the coupling.

Does this sound reasonable, or am I missing something?

Thanks.

John

[Don Moyer]

John,

It's very unusual for the threads in the coupling or on the bolts to strip. We have reports of the flange of the coupling becoming "wavy" from the pulling of the bolts and the coupling not yielding.

The only pullers that we have ever found to be useful are the type that have a split plate which slips behind the coupling and attaches to a long threaded shaft which in turn presses against the tail shaft.

Given the high cost of a good puller (around $100 in most cases), I recommend taking the entire reversing gear cage assembly (the drum part) with the coupling attached in to a local machine shop. They will likely have a selection of pullers to choose from and will be able to pull the coupling for much less than the cost of the puller. They will also be able to apply heat if necessary, which is the case in one out of approximately 75 engines or so in our rebuilding business. If the coupling comes off that hard, it will probably need to be replaced or at least have the face of the coupling re-machined to make it flat again.

Don