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Flexible Coupling Optima 101

Flexible Coupling Optima 101

Postby boatmonkey » Thu Sep 10, 2015 11:25 pm

Pieces removed.jpg
View of removed parts after cutting
Pieces removed.jpg (213.11 KiB) Viewed 1734 times
only two removal screws.jpg
Back of the flange showing the "Pusher Bolts" inserted
only two removal screws.jpg (197.11 KiB) Viewed 1734 times
Flexible coupling 1.JPG
The complete coupling right after failure
Flexible coupling 1.JPG (149.49 KiB) Viewed 1734 times
So after 27 years of service, the flexible coupling from the transmission to the prop shaft failed (dramatically). After ascertaining the issue, I sailed to my home mooring and got to work learning what to do next. First up, what is this thing made of steel, rubber and aluminum? Turns out the coupling is a old Centaflex unit. There are replacement parts which is a good thing. Gavin directed me to the right part as well as some intel about the next big issue... How the heck do you remove this old beast? I got the engine side off easily by removing 4 nuts. The back half on the other hand wouldn't budge after removing all 5 bolts. I learned by inserting 10mm bolts in the "threaded" holes on the flange and tightening them, you push off the collet and viola!

Though similar in theory to the new flexible coupling, the old units apparently bind up and do not release in the normal way. I tried all things and no luck. I was also informed that most just end up cutting the piece off. In the end, that is what I did... with an angle grinder.

The work is tough going and sparks fly everywhere so be careful to position flashing or other non flammable material in the area before you start grinding and wear protection!
You'll notice the flange holding the collet is split in the middle... Mark the collet so you can cut through it matching the split in the flange. With the collet split, it will fall off the flange and it too will come free leaving the naked prop shaft.

The last pic shows my coupling (prop side) off the boat. You can see where the "pusher bolts" left marks in the back of the collet. Perhaps a bigger punch and mallet would have convinced the thing to come free?

Here's hoping the spare goes in without requiring the shaft to move... Zephir is still afloat and I can't mess with the shaft right now!

It seemed like a big job and, in the end, it was no walk in the park, but it is doable so keep at it. Technology Afloat can steer you to the correct Centaflex unit for your Dehler
Posts: 6
Joined: Thu Jun 13, 2013 4:26 pm
Location: Chicago, Illinois, USA
Boat type: Dehler 34 VdS

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