Shaft question

[Carter Brey]

Hey folks,

Here's a head scratcher for you.

I want to service my stuffing box. There is so little room between the transmission and the stern tube that the packing nut cannot be backed off its threads far enough to allow access to the compression spacer and the packing within. Don't ask me why this is, it just is. It was not a pleasant thing to discover while huddled in a pilot berth in fetal position and with bigass pump wrenches in both hands, especially since it had taken me hours just to unfreeze the packing nut and lock nut.

Here's the solution that some mental calesthenics suggested: back off the bolts holding the shaft to the coupling, mark the position of the propeller with regard to the hull outside, and slide the shaft aft about 2 inches, allowing the packing nut to fall off. Remove compression spacer and old packing, put in new packing, replace compression spacer, and slide shaft back into position while positioning the packing nut so that it goes back on the shaft as the latter comes forward. Retighten bolts fastening shaft to coupling.

As far as I can see, since the coupling itself would not have moved, and would at no time have been disconnected from the transmission, there should be no need for re-alignment. The keyway on the shaft as well as the bolts would all be back where they started because I had marked the orientation of the shaft before starting.

Comments?

Many thanks as usual,
Carter

[fenixrises]

Hi Carter,

Sounds like a good plan...except for one leeeeeetle hitch.
Convincing the shaft and the coupling to divorce themselves while in the presence of an obviously very disturbed human...offering himself up for sacrifice in the proper fetal position on the alter of the quater berth.

To overcome this problem, as it most probably exists, a possible solution lies in offering up sufficient sacrifice.

You, with appropriate supplication, appeal to the "God of those once seperate, but now forever joined" a penance in this form.

Obtain, at modest cost, four bolts of the same thread as the transmission flange but longer. Add one small piece of round metal to use as a spacer, sometimes an appropriate diameter socket works.

Then with prayer(usually in the form of epitaths known only to sailors of low berth) loosen the bolts holding the shaft flange to the transmission flange. Slide aft. Insert the round metal spacer between the forward end of the shaft and the center of the transmission flange. Slide the shaft forward. Insert the new longer bolts, hopefully ones with full length threads, and slowly tighten said bolts one at a time. Be careful to only tighten the bolts a turn or so at a time working around the shaft flange in a pattern.

If you have used a sufficient quantity of annointed penetrating oil and made the required blood sacrifice, that is only accepted from skinned knuckles, your labors should be rewarded in the seperation of that which was "once seperate, but is now forever joined".

Then and only then will you be allowed to proceed with the "Repacking of the Stern Gland" ceremony.

Before re-assembling the shaft and flange it would be a good idea to ask the "Oracle" which of the many available lubricants would be the most ideal for application to the mating parts to insure an easier future seperation of those "once seperate, but now forever joined".

In the event insufficient distance is available to insert a spacer to facilitate the seperation of that which was "once seperate, but now forever joined" please see prayer definition above.

Consumption of modest to large quantities of one of the elixers of your choice will many times spur the creative energies into helping you find the best choice of wording for your prayer.

Of course shouting and screaming sometime help to relieve the tension brought on by performing this ceremony.

Take care,
Fred

[Neil Gordon]

... allowing the packing nut to fall off.

You mean into the bottomless bilge?

[Carter Brey]

Fred,

Ingenious. I had hoped that there wouldn't be excessive binding between a polished SS shaft and a coupling, but one never knows. And my projects often escalate uncontrollably as one problem leads to another, so that situation would be all too typical. Do muttering and sighing count as prayer?

Two things: 1. Don't you think that this procedure that you outline would mess up the alignment? 2. How difficult is it typically to slide a prop shaft through a cutless bearing? Can it usually be done just by tugging with your hands and twisting a bit? I would think there would be very little resistance, but I'm new to this kind of thing.

CB

[Carter Brey]

You mean into the bottomless bilge?

Yeah, but I've got Jimmy Hoffa, Amelia Earhart and Antoine Saint-Exupery down there ready to catch it.

[Jim Evans]

Carter,

I just went thru a cutlass bearing change on my CD33, and it took me a few hours to remove my shaft from the coupling. The "socket sandwich" that Fred refers to works well, and to build on his advice, I suggest you get a can of GM's Heat Valve lubricant - it's the best penetrant I've found. Go to any GM dealer, and ask for part #1052627. Secondly, when you buy your bolts to accommodate the "sandwich", you want only Grade 8 fine thread bolts. Anything less than Grade 8, and you're liable to stretch the bolts and/or strip the threads.

[fenixrises]

Hi Carter,

The difficulty of seperation depends upon the length of time that the shaft and coupling have been mated, if lubricant was previously used(highly unlikely if it is the factory assembly that you are dis-assembling) and if you are lucky enough to have a split coupling(also unlikely from the factory on a small boat/engine combination). Hope for the best, but be prepared for the worst!!

The procedure should not affect the alignment. But do mark the shaft flange and transmission flange so that they may be remated as before.

Given that the old packing is worn it should be easy to slide the shaft aft. With the new packing, sliding the shaft forward can be a little bit tougher, but not impossible.

I did this on my 28 with no problem. The boat was out of the water when I did it.

Take care,
Fred

[Parfait's Provider]

Seems to me that you might want to check the alignment after the boat is launched and comfortable in her watery bed once again even if the likelihood of disturbing what was is miniscule.

[Wayne Grenier]

On my cd 28-the installation of a drive protector-the hard plastic round thingy-made it impossible to change the stuffing box packing without pulling the engine-however-I went years and years without replacing the packing until an incident occurred where the vent hose got wrapped around the prop shaft inside the boat and the wire in the vent hose cut the shaft log hose to ribbons-this neccesitated cutting the existing prop shaft with a sawzall and replacing the shaft and the stuffing box with a dripless seal-we can debate endlessly about which is better-a stuffing box or a dripless seal-but if you do not have the room to back the packing nut off and get to the packing-there s not much you can-my advice? unless you have tightened the packing nut all the way and you are still getting significant leaking-I'd leave it for another day-otherwise-pull the prop-cut the shaft before it enters the coupling-unbolt the coupling and take the prop shaft and the coupling to a machine shop so they can press it out and make you a new prop shaft-it may cost $100-150 for a new prop shaft and key way all machined-then you can reinstall the shaft and the coupling and renew the packing-it depends on how much your time is worth-cause your propbaly going to spend several hours stuck in the back of that motor trying to separate the shaft from the coupling with no guarantee of sucess and you may have (probably) scored the shaft anyway after years of running it through the stuffing box-so it won't seal anyway and you will have to replace it-a boat yard will not screw with a prop shaft -they cut them and put a new one in-so either live with the old one or replace the shaft-my opinion is if its been in salt water for 15 years-you need a new one (whatever it is )-get a sawzall-an extension cord and some goggles!! and have your prop checked and retooled while you at it-and you good for another 15 years!

[Boyd]

Hi Carter:

I am assuming the boat is out of the water and has a stuffing box arrangement similar to mine. If not disregard this and try the techniques proposed by the previous posters.

There is a piece of exhaust hose that makes the connection between the fiberglass tube which passes through the hull and the actual stuffing box fitting. At least that is what exists on my boat and several others I have seen. I would cut this rubber tube right behind the end of the bronze stuffing box fitting. Then split the rubber hose which is still attached to the bronze fitting so it can be removed. Simply reinsert the bronze fitting into the now slightly shorter hose and set the new hose clamps. This should give you enough space to repack the stuffing box. A Dremel with an abrasive cut off blade or a hacksaw blade work nicely. I like the Dremel in particular as it is so small. Enjoy the smell of burning rubber when using the Dremel on rubber hose, as it adds to the ambiance. Shortening the hose puts the "rub" spot for the new packing on a new unworn section of shaft and may result in an improved seal. The rubber hose is typically longer than the fiberglass tube by enough to make this work. If its not then you are faced with pulling the coupling flange anyway.

Another possibility is you may be able to loosen the hose and slide it back along the tube. Not easily done as they tend to bond permanently in place.

If you elect to use the socket sandwich do so carefully. Tighten all bolts equally in sequence so as not to warp the transmission flange. Warp it and you are truly have a disaster. I suggest making a special steel plate to use instead of relying on the transmission flange. Bend the prop flange and you can get another for $40 or so. Bend the transmission flange and you are looking at a rebuild. I tried the socket sandwich but my flange would not give it up. The flange and shaft are machined to tolerances for a "interference fit". Meaning they are literally forced together. The bulge created in the shaft by the locking bolt is another sticking point. I ended up cutting the flange with a Sawsall.

If the coupling will not come off have you considered sliding the engine forward? Yes you will need alignment but according to my mechanic an engine alignment check is a very good idea every few years.

Boyd
s/v Tern
CD30 MkII
Fort Lauderdale, Fla.

[Carter Brey]

Boyd,

That's a very good, much simpler idea. Thank you. I do believe there's enough hose there for that to work.

CB

[Boyd]

Hi Carter:

I had another thought on how to increase the chances of success. The stuffing box fitting extends back into the hose about an inch. Instead of cutting off the whole thing just cut about half way back or in the middle of the fitting instead of behind it. Leaving a half an inch may be enough to let you pry the fitting out. Usually the hose bonds to whatever it is clamped to with unyeilding tenacity but taking a small screw driver and forcing it under the hose to break the bond will often work it loose.

Slicing off just half the distance should increase the odds of having enough hose left to work with when you put it back together. Let us know how the whole thing works out.

I use either liquid dish soap or silicone O ring grease to help lube the hose before insertion.

Boyd
s/v Tern
CD 30 MkII
Fort Lauderdale, Fla.

[Carter Brey]

Boyd,

I'm feeling pretty confident about this idea. I can visualize exactly what you're talking about. I like the plan not only because it's simple and avoids the potential problems inherent in shaft movement, but also because it allows me to take out my feelings of aggression toward the installers of this assembly on the hose.

Questions:

1. Any trick to making a reasonably fair cut? I mean a cut perpendicular to the long axis of the hose, so I don't end up with a meandering lip that's hard to seal at the bronze flange.

2. I plan to use a coping saw with the blade oriented to cut upwards for the bottom of the hose; I don't think there's enough room to get my Dremel underneath. Is this what you did?

Many thanks,
Carter

[Boyd]

Hi Carter:

Fortunately I had enough room to manipulate the Dremel around the top and bottom of the hose. The abrasive cut off wheel is both safe and fast. Then I made the final side cuts with a piece of hack saw blade wrapped with tape. It cuts faster than expected. The coping saw idea should work. There is a nasty wire in the hose. I used side cutter pliers to clip it off where the Dremel wouldn't reach.

No secret to getting a straight cut. Since you have to do at least part of this blind. It is what it is. Driving by at 45 mph you wont be able to tell its not perfect.

Boyd
s/v Tern
CD 30 MkII
Fort Lauderdale, Fla.

[Jim Lewis]

I guess the hose on stern tube is all the way aft and hasn t moved forward........I know to my shock on day I was gonna add packing
to my stuffing box and hose turned on tube, to my surprise no
clamps back there......good luck......