Cutlass Bearing & Prop Shaft Replacement
- Last Updated on Thursday, 19 January 2012 01:13
A. J. Matthews, Ay Mon, #605
First make sure that the stern tube is in good shape and that you don't have slop between the bearing and the tube. The Cutlass bearing should be snug in the tube with no play.
If there is play, you will need to build up the interior of the stern tube with epoxy. After cleaning away the deposits, use the old cutlass bearing as a mold or base, cover it with some lubricant then use epoxy to fill the voids within the stern tube (inject with syringes or apply the epoxy to the outside of the cutlass. The lubricant will keep the epoxy from curing on the old cutlass -- Don't go crazy with the lubricant or the epoxy. Less is more here.) Make sure you leave the attached shaft in place, as this will insure the proper alignment for the cutlass bearing.
If all is well, take a good look at the set screws in the stern tube. If the set screws are loose, drill this area out and fill it with epoxy, using your old cutlass bearing as a backer with a coating of lubricant (WD 40) so the epoxy will not stick to the old cutlass.
Once the epoxy is cured, drill and tap to the thread size of the new screws and insert the new cutlass bearing into the stern tube. Leave at least 1/8 - 3/16 of an inch sticking out of the stern tube, so you can get a wrench or channel locks for future removal. Then mark the cutlass bearing with a pencil or marker in order to drill dimples into the sides of the cutlass bearing which will line up with the set screw holes. This will keep the cutlass bearing from turning with the shaft.
I used Allen screws for my set screws. The former owner used hex head bolts. Also, some tritons were fitted with half cutlass bearings, as opposed to the 3 1/2 in long bearings that are proper. You may save some money or work replacing a half bearing, but you will loose in the long run. I pay about $22.00 for my cutlass bearings. compare that to having a new shaft machined!
Lastly, you may consider drilling some angled holes into the stern tube fore of the cutlass bearing. These holes (angled forward) will provide a constant source of water over the surfaces of the cutlass bearing which will reduce friction and wear. Use a 1/4" hole, 5/16" if you must. Put the hole(s) on both sides of the stern tube about 1 1/4 forward of the leading edge of the cutlass bearing (that would put it about not more than 4 3/4 of an inch from the aft end of the tube. angle them in about 30-45 degrees.
Play with the angle and location before you drill. Remember, measure twice, cut once.
Also, while the boat is out of the water, remove, inspect, repair, replace, repack your stuffing box. Take it out, brush it off, clean it up and repack with Teflon based flax packing. If not, simply pay the money for a drip-less seal and forget about it.
In dealing with the flax packing, do not cut the packing square. Cut both ends on a 45 degree angle then insert two pieces with the seam on opposite ends of the shaft. This produces a better seal.
George Jones, #236, Ca Ira
have a picture of the cutlass bearing system that A.J. describes in the MIR. A.J. has a drawing of the system in his MIR article and I had taken a photo on my boat without any bottom paint to show how it looks in real life.
I read in the 1990 improvement guide that Pearson used a standard cutlass bearing cut in half as a cost saving measure. The one I removed was the short (cut?) bearing. I will be boring the shaft log to the proper depth today. I'll let you know how it works out.
Rob Squire, #96, Head Over Heels
I've done two cutlass bearings on Head Over Heels. As I recall, I measured the ID of the stern tube both times....mostly the second time because after all the rum, my memory isn't what it used to be. Anyway, to make a short story long, I had a problem both times with the stern tube moving a little. Each time, we moved it back into place and just cut the rest of the cutlass off....usually about a half of an inch or so. I resealed it the first time with Red Hand, but used nothing the second because the movement was slight. No leaks.
To remove the flange from the shaft, put a socket on the head of the shaft and using longer bolts, re bolt the flange together. Snug the bolts evenly and slowly, letting the pressure do the work. Too much uneven pressure will warp or even break your flange. You may need to tap the flange on the shaft lightly with a hammer, or carefully heat it with a propane torch. It will slide off, slowly at first, then once it is broken free from its years of growing attached to its shaft, more quickly. You may need to add another socket as the shaft pushes out.
Removing the cutlass is a different deal. The both times I have replaced my cutlass, I have had to cut it out. First, on both sides of Head over Heels cutlass, there is a set screw. Scrap through the bottom paint about an inch forward of the shaft exit to look for a place for a set screw. Mine are allen heads and were easy to remove. Using a Sawzall, I cut length wise through 90 percent of the thickness if the cutlass brass. I then moved over about a quarter of an inch, and made another 90 percent cut. Using a cold chisel I peel out the quarter inch piece. I then slightly collapse the bearing and slip it out.
Measure the inside diameter of the hull tube. Cutlass bearings are available at most chandleries, but a yard manager will know where to get a hold of one.
Just as a side note, I installed a PYC dripless shaft log, and indeed, it is dripless. I was so impressed, I installed one in an old ski boat. Again, bone dry. I like the product.
Rob Griem, #302, Iota
The cutlass bearing I dug out of Iota yesterday is 7/8" I.D. and 1 3/8" O.D. The name code for it is "Barracuda" from Trellex-Morse. You will probably have to cut it down from its 3 1/2" length. I've done the cutlass bearing twice now.
I agree with Rob Squire in that the best way to remove the flange from the shaft is to press it out using a spacer between the shaft and the engine using longer bolts. I did this and it came apart easily. To remove the cutlass bearing, I used a different approach. I made a crude hammering device resembing a long bolt with heads at each end, with a metal weight inbetween the heads. The one head of the bolt was just big enough to slide inside the cutlass bearing. By hammering on the opposite bolt head, the cutlass bearing came out intact. Remove the set screws first. I also installed the Lasdrop, and have been very happy with it.
Milt, Genevieve, #88
I just went through the shaft ordeal a couple of weeks ago. The bolt/socket method did not budge the shaft at all! Since I knew my shaft was shot, I cut the shaft just aft of the coupler...slid right out after that. I was then able to press the remaining stub out with a hydrolic press. The sawzall trick worked fine on my shot cutlass bearing. The replacement bearing measured 1-3/8" O.D. by 7/8" I.D. The name code for this bearing was "Atom" (apparantly that meant something to the prop guy!) The new shaft cost $140.00, cutlass cost $54.00. Got 'em from Admiral C&B Propeller, 6235 S. Manhattan Ave.,Tampa,Fl 33616 , 1-800-771-9476. Talk to Tom the salesman, tell him I sent you , I think I own stock in the company now!
Obviously, the symtom of a shot cutlass bearing is that the vibration is like an out of balance washing machine!
RELATED SITUATION "I'm slowly working through the steps to replace my cutless bearing. I've got the prop off, and now I want to press the prop shaft out of the coupling flange. There's a small pin with an even smaller hole on the end coming out of the flange, which looks like it goes down through the shaft. There was stainless wire run through the small hole and wrapped around the flange.
Does this sound familiar to anyone? Is the pin just pressed in, or should it unscrew? Unfortunately it's rather rusty, so I'm worried about snapping it off. Suggestion for removing the pin would be appreciated."
Dana Berube, JADE, #99
I just removed this entire assembly from my boat a couple of weeks ago. The "pin" that you see is actually a set screw- probably with a square head. Mine was safety wired- just as you described. I would soak the screw and threads with PB Blaster or something similar. It would be best to not break it off - but, it wouldn't be a disaster- since you coulddrill it out of the coupling if necessary. I would soak it for a couple of days- tap it gently with a hammer to loosen- and give it a go. Make sure that your wrench fits the head as snug as possible- an adjustable wrench may be your best bet. Take your time and go easy.
BILL BELL, KIALOA, #41
Your ultimate fallback position is to put a new, metal cutting blade in your sabre saw and cut through the shaft at any accessible spot. The shaft bearing area is always worn more than you thought. If you spend much time in shallow water and your bottoms are sandy, the wear will be accelerated. I noticed a great difference when I moved from Cape Cod (MA) silty conditions to Maine and its rocky condition. The innards of my Atomic 4 are cleaner these days, my impeller seems to last and last and the wear on the cutless is the least I have ever seen. In Cape Cod, I used to see significant wear after two years. Once the shaft is cut, all else follows easily. I would suspect that you have come on a threaded machine screw with a square head on it which is the safety lock on the woodruff key securing the prop shaft to the flange. The small hole in the end was for a safety wire. The last time I was through that area on by old tub, I replaced the original hex head cap screws bolting the flanges together with stainless steel bolts with ss lock nuts and washers. Before installing them, I threw them in the vice and drilled holes in them for safety wires as well. So one loop of wire catches the three flange bolts plus the one woodruff key lock screws. No big deal - it just tidies things up. Over the years, I have replaced every fastener ever used with stailnless. Then you can take stuff down without banging up a nice paint job.
Now I want to lay a good one on you. One that almost cost me money once - except that I won the bet. What I want you to do is this: Before you put the new cutless bearing in place, assemble the shaft into the flange, lock down the woodruff key - put it all together with the shaft sticking out through the tube that supports the bearing. Put the prop on the shaft. Put the transmission in gear. On other words, put the whole mess back together without installing the bearing. Then get out of the boat, get down by the prop, put a wrench on one of the prop nuts and see how true the shaft turns. You may be amazed at how much "off" it is. Of course, I hope yours will be perfect - but I can tell you that they can be really off badly in a high percentage of cases. I had a real battle with a prominent New England prop/shaft shop about this some years ago. A point in the center of the prop end of the shaft described a 5/'6" diameter circle ! I had quite a time resolving the matter with the shop that had supplied the shaft and flange. . I was told "Oh, it won't make any difference" and "Did you line up the engine?" and so on. I finally got someone who understood and it came back, no charge, centered perfectly. So - do check yours. If nothing else, the checkout will make you feel competent and deservedly reassured. Also, if you can find it, look for a cutless bearing that has flats on the bearing surfaces. Most of them have curved or "ribbed" surfaces. The latter have much less life. Be sure the water passages into the bearing housing are open and that the actual bearing is secured solidy. I prefer to bore holes in from each side of the bearing housing and drill and tap the bronze shell of the bearing. The bearing is then set in resin and locked in place with two ss hex cap screws - again, safety wired in place.
Mickey Feldman, Triton #644
If you have a set screw, it will probably bear directly on the woodruff or straight key that keys the coupling to the shaft. For some applications a second set screw is used at 90 degrees, but I wouldn't expect one here. However, it may not be a set screw. An alternate way of locking couplings to shafts (in general, about Tritons, who knows?) is to pin them with a pin that goes entirely through both the coupling and the shaft. If the coupling was designed to be used this way you will probably see no evidence of a key, or of a keyway when looking at the aft end of the coupling. (Although I can imagine someone using the original, keyed coupling, drilling and pinning it for lack of a key, set screw, or just because they favored pins... ) In any case there will be no head on the pin that you can fit a wrench to.
I don't believe I've ever seen both a key and a pin used simultaneously. If you can see that the pin (or evidence that a hole) does in fact go all the way through, then it may be that at some point in the boat's history this type of connection was used. I presume the original method was a key, it's certainly more common.
If your shaft is pinned, it is almost certainly with a taper pin. Take a punch slightly smaller than the hole on the small side and tap it out with a hammer. A penetrating oil soak first etc, won't hurt, but is probably not necessary, and unlike a set screw, you can't break it off. The beauty of tapers is that very little axial movement translates into a significant change in the amount of interference between the hole and the pin. Taper pins both snug up tightly and let go easily. Chances are the safety wire is on the small end.
If you re-use the shaft and coupling, make sure that the large end of the hole in the shaft is aligned with the large end of the hole in the coupling when you go to reassemble it. Taper pins come in standard sizes. Get a new one.
David Whyte, #397, Mandara
(...to press the drive shaft out of the coupling...) with a clean shaft, the "IN" part shouldn't be too much trouble, often they will just slip in, or maybe a judicious mallet tap or two. The easiest way to press one out from a stuck coupling is to remove the setscrews, then the bolts at the coupling. Stack up some washers or nuts between the end of the shaft and the drive flange on the engine, then gently and evenly retighten the bolts, pressing the shaft out of the coupling. often they will free up after only a bit of persuasion. If not, keep stacking more junk in there and use longer bolts as necessary. It may also be helpful to heat the coupling a bit with the trusty propane torch. if it is really and truly stuck, and will not start moving with a reasonable amount of torque on the bolts, use care not to berk on it too hard and gall the threads in the gearbox drive flange.
If all else fails, and you are replacing the shaft anyway, cut it off with a sawzall, then you can deal with the coupling itself out of the boat. A fast job on a force press, and any machine shop can take care of it.
The rudder does not have to come off.
I've never done a cutlass without pulling the shaft.
I think the prop does have to come off, but I'm not sure. If you have a 2-blade, you might be able to seek it by, but I doubt it.
The best way I've found for seperating the shaft from the flange is to place an object in the center of the coupling and use the coupling bolts to press the shaft out of the coupling.
Here is a step-by-step
1) Spray the coupling with Aero Kroyl or similar - let it set a day or so
2) Remove all bolts from the coupling
3) Find a series of small metalic object, progressively longer, that can be placed in the center of the coupling, between the end of the prop shaft and the transmission half of the coupling. Make sure the object is facing the prop shaft and only the prop shaft. There are some ledges in there. I've use things out of my tool box like sockets and bolts of the proper length.
4) Replace the bolts in the coupling and tighten them . If you chose the right length object, you should be able to press the shaft loose as you tighten the coupling bolts.
5) I've found it best to take it a bite at a time, using progressively longer objects.
Expect to spend the better part of a morning, just getting the shaft out. .
I have a large (~6" diameter) bronze cover in the bottom of my cockpit that allows access (sort of) to the cutlass area. I assume this is commen to most Tritons.
Once you get the shaft out, I would suggest replacing the rubber tube between the hull an the packing gland. I know someone whose Alberg 30 sank in the slip because the tube failed. There is special hose for it, it is supposed to not have any wire in it.
(Find) the set screws that hold it in? They will be near the aft end and might be hidden under layers of bottom paint. You should be able to get at the inside end to drive it out. See if you can find a large socket that will fit inside the tube but catch on the bearing. If you can't drive it out then you have to cut it out.
I have a hacksaw blade holder with a handle that I could get inside the bearing to cut through the bearing wall twice and remove the two bearing halves. I guess you could use a sawzall with a metal cutting blade. I always end up doing some damage when I break out the sawzall, it is not a precision finish tool. You might have to do some repairs before putting in the new bearing.
All in all you would be better off in driving it out from the inside, using drifts or a socket if you can. Use a dead blow hammer or a real sledge. Its been there for 40 years and doesn't want to leave.
Agree, there've been times the guys at work have trashed out a rubber mallet trying to knock something loose, only to find all it needed a real blow from a mini-maul to knock it loose.
When things are realy frozen in place, I've often had luck giving it a few thumps in the other direction. They'll often move far enough back that when you hit it from the right side it has enough inertia to get past whatever was stopping it.
Art freeman, #525
On the prop bear issue. I could not get mine out on a '63 West Coast Triton and used the hacksaw to cut the wall. There was no screw. The new one was also a very tight fit (too tight) and the instructions talked about not dropping the thing if you were to shrink it in liquid nitrogen (!!!) to be able to get it in. Maybe that is how they got it in! Being fresh out of liquid nitrogen, I filed it a little smaller to be able to tap it in w/o a sledge hammer, and then drilled a set screw on either side using maybe a #8 or #10 SS screw going into a dimple in the brass bearing wall. No problems for 700 engine hours and I figure I can get the thing out this way to replace w/o taking the shaft out.