flex coupling/propshaft removal help? - SailNet Community
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post #1 of 4 Old 05-07-2011 Thread Starter
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flex coupling/propshaft removal help?

can anyone with a centa or vetus flex coupling to your marine engine answer the following questions:

it appears that these flex couplings mount easily with 6 bolts onto the coupling in the gearbox (my engine = a yanmar 3JH4E 40 hp, for which there is an adapter flange)

1--in order to remove the prop shaft from the centa or vetus, do you just undo the 6 mounting bolts of the flex-coupler , which bolt heads s face aft in a circular arrangement ? and then start pulling the propeller shaft outboard and aft?

2--what bolts retain the prop shaft inside the flexible coupling ? those same 6 bolts, or some other set of bolts or fasteners that need to be loosened?i cannot understand how the force created by the fore and aft install directions of the 6 bolts convert to a clamping force , to keep the prop shaft engaged inside the flex coupling itself.

i need to replace a bent prop shaft and worn out cutless bearing . am having trouble getting the prop shaft out. i am not able to pull the prop shaft out rearward from the flex coupling even though i've already removed the 6 flex coupling bolts. (i have already removed the propeller and cutless bearing from the prop shaft....)

thanks in advance for as much detailed advice as you can supply...

on the hard, and going nowhere til i figure this one out...
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post #2 of 4 Old 05-07-2011
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Looks like a taper lock internally... check the graphics here: (Assuming this is a same/similar coupling)


Also from their PDF catalog:

• The coupling is fastened to the plain cylindrical propellor shaft by means of a securely dimensioned clamping hub, thus expensive machining of the propellor shaft is not nec- essary. Length adaption is simple, and there is no weak- ening of the propellor shaft diameter caused by a bore or keyway.
So it looks like you need to pry/back off the collar under the bolts once they are loose... this should release the tapered collar's "grip" on the shaft. (Qualifier... I've not done this, just going by the 'pictures'.....)


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Last edited by Faster; 05-07-2011 at 02:07 PM.
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post #3 of 4 Old 05-08-2011
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Havn,t seen this particular arrangement either but have worked on plenty of gearbox drive shaft setups over the years.
Faster seems to have the right idea, but it often requires a sharp tap on the shaft end directed into the coupling to break the taper lock. If reusing the shaft use a copper or lead mallet.
If this doesn,t work a photo of the assembly would help.
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post #4 of 4 Old 12-20-2015
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Re: flex coupling/propshaft removal help?

I have Centaflex coupler and I think the internal "rubber" damper has begun to weaken which is producing a worrisome "CLUNK" when shifting into forward gear. I've tried to remove the bolts (large allen-type screws) from around the edge of the housing, but they are seized on (by design?). Does anyone have any advice for removing the unit from the prop shaft?
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