[C320-list] coupler re-install

[Rick Sulewski]

Ted,
I found that installing the coupler as you suggest works while being certain
to line up the coupler set screw holes with the shaft dimples and then
installing the set screws followed by taping in the key. That arrangement
worked better in my situation when I recently removed the coupler to replace
an aging 20 year old shaft log hose. I initially attempted to install the
coupler by installing the key in the shaft and then driving the shaft into
the coupler when that prop shaft coupler was attached to the engine side
coupler, using piece of wood to prevent damage to the shaft threads with the
prop installed, but that approach did not work for my. The boat, while in
its cradle, naturally experiences a degree of hull flex and the shaft could
not be driven all of the way into the coupler even with a large degree of
tapping force at the prop end of the shaft because the shaft did not totally
line up when it was half way into the coupler. Further movement was being
held back by a portion of the leading edge of the shaft resisting against
the coupler due to the degree of  hull flex, creating misalignment while
resting in the cradle (causing increasing amounts of excessive force
necessary to continue to drive the shaft into the shaft side coupler which I
opted not to continue). I then had to remove the partially installed shaft
from the coupler with the flange puller and reinstall the coupler by driving
in the key from the engine side after being certain the coupler set screws
were seated into the dimpled shaft in order to line up the key slots on the
back side of the shaft & coupler. After tapping in the key more than halfway
in,  I met with some resistance and then reinstalled the shaft side coupler
to the engine side coupler and then only had to tap  the end of the prop
shaft to further drive the key into the last portion of the coupler,
followed by separating the coupler for additional taps on the key leaving
the key almost flush with the face of inside edge of the coupler.

 It is important to understand that the coupler should be tightly fit on the
shaft and the key helps to not only keep the shaft from rotating within the
coupler, but also serves in my case to fit very snugly between the shaft &
coupler. If the shaft to coupler fit is too loose, then the shaft could work
loose (wobble) within the coupler and that could result in the shaft
separating from the coupler if the shaft side of the set screws shear off
when operating suddenly in reverse or under strong power in reverse. That is
why it is not advisable to grease or lubricate the shaft when reinstalling
the shaft in the coupler because the rust that naturally develops between
the shaft and coupler serves to also provide a tighter tolerance over time
between the shaft and coupler. Do not forget to tightly wired the set screws
to prevent them from working loose.

As an additional precaution it is advisable to have your prop zinc located
securely just ahead of your prop strut by a length not greater than exists
between the coupler and packing log nut in the event the prop shaft may ever
separate from its coupler with the intent of relying on the shaft zinc to
(hopefully) keep the shaft from totally exiting/departing beyond the packing
log nut and creating a large flow of water to overwhelm the bilge pump. 

Hope this reply is clear. If not, feel free to contact me off line at my
email address.
Rick 95 320 hull #277

-----Original Message-----
From: C320-list [mailto:c320-list-bounces at lists.catalina320.com] On Behalf
Of tharrison at innovations-plus.com
Sent: Saturday, April 25, 2015 10:45 AM
To: C320-List at Catalina320.com
Subject: [C320-list] coupler re-install

Do you put the coupler on the shaft first and then tap the key in with a
hammer?

 

 

 

Ted Hull 424