Stuffing boxes

[pschauss]

What do you guys think of the condition of my stuffing box hoses shown below? As a minimum, I plan to replace the clamps since they look a bit corroded. As near as I can tell from the maintenance receipts which came with my boat, these have not been messed with since 2013.

http://www.ipernity.com/doc/307687/49358912

http://www.ipernity.com/doc/307687/49358906

Thanks

[Donmystic1]

Everything looks tired.
I will be checking my own on my 28.

[Bruce]

I would replace not only the clamps but the hose. And when I had it apart l'd clean the packing gland in muriatic acid and add new flax packing.

Stuffing box 1 looks like the heads of the bolts have a gap and not tight which indicates the the gland is tight only from corrosion. Replace the hardware also.

[pschauss]

Thanks for the pointing out the problem with the bolt heads. Interestingly, it was the other one (starboard side) where I caught a serious leak last week.

Looking closely at the gland I can see that place where the left side bolt head sits has a chunk missing. Should I replace the whole gland while I have everything apart?

[Bruce]

Yes. If you look at the one, the ears are bent indicating it was over tightened to compensate for old hard packing.

[Amberjack]

Peter-I have two original 1 3/8” stuffing boxes in good condition. You Are welcome to them if you want to pay FedEx packing and shopping from Seattle, plus a donation to the board. If interested I can send pictures.

[pschauss]

Doug,

Thanks for the offer. I will pm you with my email address so that you can send me pictures.

[pschauss]

Looking at the various suppliers I see that there are two types of stuffing boxes, the kind with two bolts which compress the flanges like I have and the kind with a single large nut and lock nut. Is one type better than the other? I would think that the kind that I have would might allow you to compress the flax backing unevenly if you did not keep the flanges parallel.

[Tony Meola]

Peter

I have onlky had experience with the doubke flange bolt set up. I never had a problem keeping them even. Once I had them set, any adjustments needed I always tried to take the same number of turns on each side.

[pschauss]

I assume that I will need to detach my prop shafts from the couplings on the transmission. I took a quick look at them today and it looks as though the shaft is held on to the coupling by a set screw with a hex head. Is this correct?

I have receipts indicating that the prop shafts were replaced in 2013. Is it likely that I will have problems separating the shafts from the couplings? What should I do if I run into a problem getting them out? My boat is still in the water and I don't expect to be starting this project until late November or early December when she goes into yard. Should I start soaking this area with penetrating oil now?

[Tony Meola]

Peter

Spraying the coupling and the bolts holding the coupling will not hurt. Depending on how rusty the coupling has gotten will determine if the coupling will separate easily.

Yes there is a set screw. When you slide the shaft back and since the boat is out of the water, make sure you spray down the cutlass bearing in the strut. What I usually do is take a spray bottle, I put a little dove dishwashing soap in it, and water. Spray the cutlass bearing right behind the strut. The water will and soap will run down the shaft through the strut and bearing. This will lubricate the bearing so the shaft will slide back for you. When you pull the shaft back up repeat the process.

[pschauss]

What kind of packing should I be using for my shafts? I see some posts on this subject from about 4 years ago. Any new ideas on this subject?

I recall someone saying to use natural flax on the rudder shafts. Is that still the consensus?

[Carl]

The locking screw that holds the shaft is usually a hardened square bolt that gets locked into a small dimple on the shaft. They tend to lock up in place...yes start spraying some penetrating oil on them, also the coupling bolts. You said hex...could be, but was probably replaced. I do as I am not a fan of the hardened bolts as they tend to break off when cranked on after they lock up...then drilling out is a royal pain.

The coupling, if solid design is usually a very snug fit on the shaft, as in pressed on. They go on tight and come off tighter. Trick here is to use the two couplings and a spacer as a "shaft puller". You do this by seperating the tranny and shaft couplings. Then insert a socket that is a bit smaller then the shaft diameter centered in between the two. Then use bolts that will extend the gap and tighten them in a criss cross pattern pushing the shaft out of the shaft coupling.

If you have a "split coupling" which has a built in clamp on the end, you loosen as per "solid" design then the cross bolts, drive in a pair of wedges opening the gap a hair. Then the coupling should come off with a couple light taps...or use the shaft puller trick.

If your lucky the last mechanic had the shafts coupling fitted to the shafts. That is they turn them down precisely to a point they fit snug together with no play, but not so tight as they need to be pounded on or off.

If the coupling do not come off I usually slice them with a cutoff wheel over cutting the shaft. Shaft prices have gotten out of control...couplings are relatively inexpensive. We used to have one mechanic here that gave the couplings 10 minutes...didn't come off he sawzalled the shaft.



As Tony said, to slide shaft back use water and soap on the cutless bearing for lube - NO OIL on the Cutless...oil reacts with the rubber bearing. Sometimes it swells, sometimes it turns hard (Might be a joke in there somewhere). But also remember to clean paint and growth from shaft before sliding shaft down into the cutless.


I prefer the screw on packing gland nut design...but not by alot. The screw on is always gives a square and parallel squeeze. But the fine thread on the adjustments tend to corrode up and can be a pain to adjust if not watched and cleaned and adjusted periodically. Also some don't snug up the locking nut enough allowing the glad to overtighten or loosen with rotation of the shaft. The double bolt style you have can be adjusted out of square causing sealing and binding issues. Done right, which is not that difficult to do, they both work very well.

[Rawleigh]

Carl: How many thou should the friction fit between the shaft and a solid coupling be for 1 3/8 shafts? 1 or 2 thou?

[pschauss]

How do you get the coupling back on?

[Carl]

Carl: How many thou should the friction fit between the shaft and a solid coupling be for 1 3/8 shafts? 1 or 2 thou?

Usually when we press items together we look for about .001 press fit per inch of diameter. So a 1-1/2" shaft would be a thousandth and a half press fit. Easy with a press and or heat. A shaft in a boat is a different story and I'm not into pounding a shaft into a coupling when attached to the trans and heating a coupling in a boat is not for me either. Then removal is a bear as well.

So shafts up to 1-3/8" diameter come nominal with a tolerance on the diameter of +.002/-.001, shafts 1-1/2"- 2" allows +.003 /-.001. Couplings are to size to +.001 or so. Then add in the burs around the machined keyways...it makes for an exceptionally tight fit. To tight.

Me, I prefer size to size on solid couplings.
On clamp fit couplings I'll allow .0005 or so clearence and as I clean up the keyways the coupling just about slides on freely when wedged open. A good dimple drilled into the shaft and lock up the bolts...its not moving.

For the heavy handed offshore guys that back down like no tomorrow, we add keeper rings to the setup. That is we cut a groove around the end of the shaft, 1/4" from the end, 1/4" deep and 1/4" wide. On the coupling we counterbore the back 1/2" + larger in diameter by 1/2 deep. Then machine a ring, cut in half like two half moons...Coupling goes on past the end of shaft...split ring slip onto shaft then coupling gets pushed back covering rings and assembled as usual, shaft cannot slip out ever. Not quite as good as a double tapered shaft...but needs less room and not as costly...easier to remove.

So to answer your question...I prefer clamp fit and a tap on fit ( with a soft deadblow) which is usually about .0005 clearance dealing with out of roundness and burs. Add a real good dimple, a long set screw nutted to secure over the square head screw. I can pull one of my shafts in a couple minutes, compared to...well if you've been around marina's it's a job and a half for many to pull the shaft.

[Carl]

How do you get the coupling back on?

If fitted, they get cleaned, then they are tapped back on.

If not fitted...clean em up, then heat and beat.

[pschauss]

How hot do I have to get the coupling? My boatyard does not allow open flames.
How do I immobilize the shaft while I beat on it?

[Carl]

I'm not the best person to ask...I've mostly only installed fitted coupling on boats. In the shop its a whole different ball game as I have presses, vises, torches and lots of room to work.

But the basics are to clean up the surfaces, file down any burs on the keyways and keys, make sure they slide relatively easy on both the shaft and coupling. Where the set screw held the shaft, make sure that area is nice and smooth, they tend ot mushroom over. At this point...try fitting it together, when clean it just may go...or seem to. IF not try to get a measurement...if not, it went before..it should go again, emery out the two pressed surfaces, clean and...

Put key in shaft and try to get the coupling on a bit. Try to tap it on...if its going pretty easy you can continue or connect shaft and tranny couplings, leave loose, from underneath with a block of wood up against the end of shaft use some persuasion to drive the shaft in. I hate pounding on the tranny and recommend having shaft fit to coupler. Also good to have someone inside boat watching progress...your looking for the set screw dimple to line up to the hole. Your not going for driving it home past that...

If heating...I like a chain strap wrench and a pair of HD welding gloves plus a large piece of brass (soft metal hammer, deadblow) I heat till bore is oversize, line it up and slide it on. When starting its easy to slightly cock the coupling on shaft, a light tap with soft metal hammer is best to straighten. Gotta be quick as it cools and shrinks fassst
How hot?? I don't know I measure the bore size, not the temp. Only time I've been apart of heating a coupling inside a boat was in a steel work boat. Not too sure I'd want to heat in a boat...aside from maybe an oven.