Drive shaft

[rappareems]

I have noticed since I put in the three blade flex-0-fold prop a couple seasons back a pretty good clunk when I put the boat in gear.  On inspecting the shaft yesterday I noticed some "wear" in the key way.  The key itself appears to be wearing and I could see some "shiny" spots of metal on metal wear and even a few metal filings.  My thought was to pull the shaft in the Fall and replace it with a stainless shaft.  Any suggestions?

[Ron Hill]

Mark : The key and keyway on the shaft are usually a matched pair.  Infact the key and the slot(keyway) are so finely machined that you can slice your finger if you aren't careful.  Also the key may not be EXACTLY square, so when you take it apart make sure that you don't rotate the key when you reassemble.  Sounds as thought that you've gotten some "slop" in your key/keyway!!
I'm sure that you probably have enough wear on the shaft that rides inside the cutless bearing to warrant a new shaft anyway.  What you might consider installing a Vetus flexible coupling at the same time (or now) as you change the shaft.  You can do that with the boat in the water.  The flexible coupling doesn't need a key and it eliminates the frequent engine shaft alignment process.  Something to think about!!

A few thoughts.   

[Bob K]

Mark,
I'm not familiar with the flex-o-fold design, but here is something that may be applicable...... I had a Martec folding prop on my previous boat, and also heard the clunk when putting into gear.  It was disconcerting at first, but we got used to it.  I believe it was normal, and caused by the blades initially flipping open by centrifugal force.  Used it for 8 years w/ no problems.  Did not have the keyway wear that you mention though - definitely worth checking that out.  Might want to contact the mfr about the noise.

[Ken Juul]

Both the key and the shaft are fairly soft metal.  They are intended to help with the alignment and in company with the jam bolts provide enough resistance to help keep the coupling from spinning on the shaft.  Over time, especially on the brass shafts the jam bolts can make dimples in the shaft causing loosness.  This makes the key/keyway do more work than they were designed to do.  Make sure the Jam nuts are tight.  If the key is severly worn, most hardware stores carry a selection of keys, you should be able to find a replacement.

[rappareems]

Thanks for your input guys.  Ron, I hope you know you are a legend on this site at least.  When I mention your name to my "wrench" he chuckles!