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Old 12-10-2011, 17:49   #31
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Re: Saildrive Prop Shaft Repair

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Originally Posted by rolandcavanagh View Post
I'll preface this saying that I'm a lazy and cheap Mechanical Engineer, meaning that I look for an effective solution that is easy and inexpensive, and I've been around a lot of mechanical stuff... If it were mine, I'd be looking at:

1. Repositioning the seals - adding a shim behind the seal to move it to a new place on the shaft - if there is room. Result is shafts with grooves that will get new grooves years from now. (I'm interested in the discussion about shimming the shaft, but, as others have said, I'd have to know what the arrangement is)

2. Chrome plating or metal spraying then grinding. Both are well accepted common practices. I agree with the shop that wouldn't quote it until they saw them, respect that as a sign of a good shop. End result is shafts better than new.

Sleeves work fine in safe environments, but with one side exposed continuously to sea water, I'd be very concerned about galvanic action or bonding agent (glue) failure or cutting the seal during installation, etc, etc. I'd consider this a "get-home" solution...

#1 should be easy to investigate - is there room for the seal to be further out say .015" or .020"? If so, have a shop turn a circular shim.
#2 I'd be calling around lining up shops to take the parts to for estimates. I'd plan on a day running around, and the possibility of rush charges if in a hurry. Could find the services on the Internet, but have to ship and "trust" that they will be done right.

Easy for me to say... if it were mine... hope this helps.
Thanks Roland, Colemj and Perchance. Great ideas and everything helps.

I really like the idea of trying to shim seal location, but I'm concerned about the width of the gooves in the shaft. I think it would require moving the seals at least .050" and that would require some thick shims. I don't know how much room I have inside the bearing housing. This brings to mind another potential solution. The seals sit back-to-back inside a bearing housing. The shop manual shows the seals with the "spring side" of the seals facing AWAY from each other. If I put the seals in backwards with the springs facing each other it would move the location on the shaft by .100" and miss the shaft grooves completely. I have a feeling that the pressure of water on the outside seal and pressure of oil on the inside seal helps to keep seals from leaking, but perhaps spring pressure is enough??

I'll try again to find a metal spraying shop. I found another place to call.

Perchance, you said you use Speedi-seals all the time with no issues. Do you use them in any applications that are underwater? I ordered some from NAPA as one of my options and they will let me return them if I don't use them. It does seem like the simplest fix, if not the most permanent.
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Old 14-10-2011, 08:20   #32
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Re: Saildrive Prop Shaft Repair

Greg, I wouldn't recommend flipping the seals, they are designed so any possible pressure generated inside the contained area causes the seal to press tighter on the shaft. Can't rely on that circular spring to do the whole job.

Another possibility, if these seals are standard diameters ID and OD, is to get ones that are narrower so when they are fully inserted they will bear on a different part of the shaft - I'd try a NAPA store or McMaster-Carr.

Is the picture at the beginning of this thread actually one of your shafts? Concerned that it must be quite soft to have worn that much and still be sealing (meaning that the seal did the abrading - sand would have destroyed the seal also). This would make me more interested in chrome plating or spraying...

Good luck, hope to hear what you end up doing.
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Old 14-10-2011, 12:37   #33
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Re: Saildrive Prop Shaft Repair

Quote:
Originally Posted by rolandcavanagh View Post
Greg, I wouldn't recommend flipping the seals, they are designed so any possible pressure generated inside the contained area causes the seal to press tighter on the shaft. Can't rely on that circular spring to do the whole job.

Another possibility, if these seals are standard diameters ID and OD, is to get ones that are narrower so when they are fully inserted they will bear on a different part of the shaft - I'd try a NAPA store or McMaster-Carr.

Is the picture at the beginning of this thread actually one of your shafts? Concerned that it must be quite soft to have worn that much and still be sealing (meaning that the seal did the abrading - sand would have destroyed the seal also). This would make me more interested in chrome plating or spraying... Good luck, hope to hear what you end up doing.
Roland, thanks again for the guidance. I was afraid flipping the seals would be a problem. Good advice on trying different size seals. I'll see if NAPA has something compatible.

The picture is one of my prop shafts and the other one looks just like it. The pic was from last haulout in 2009 and we've made 2
Bahamas trips since then. I'm expecting the grooves to be deeper when I haul next week. When I remove the seals they look pretty good and I've never had water inside the drives, so I agree... the shafts are soft

I called a big industrial machine shop in Tampa to see if they would "metal spray" the shafts, but they don't handle small jobs. They do work on shafts for cargo ships and did give me some advice. They advised against metal spraying because it wouldn't seal properly (don't know why). He advised me to put a sleeve over the shaft with some #1 Permatex as an adhesive and to insulate the metals from each other.

I received the Speedi-sleeves from NAPA and I'm very concerned about using them. The sleeves are advertised as stainless, but when I put a magnet on them, it lifted them just fine. I think that means the stainless quality is not good and they may rust out. Anyone use Speedi-sleeves in salt water? Did they hold up?
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Old 15-10-2011, 07:00   #34
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"Stainless" steel (formally "corrosion resistant") comes in many alloys, and only the 300 series exhibits non-magnetic behavior, however, if a 300 series is cold worked (rolled, bent, etc) or welded it becomes somewhat magnetic. Typical boat stuff is 316, and parts are usually stress relieved to improve corrosion resistance, so they typically won't respond to a magnet. 300 series is also relatively soft. We have a set of kitchen knives that hold an edge, are very stiff, and very magnetic, yet corrosion resistant. I'll bet they are 440C, an alloy that is tough and can be hardened.

Long story, the point is that the shims are probably either an alloy that can be hardened for wear resistance, or are a 300 series that have been cold worked. Either way they can be magnetic and their salt water corrosion resistance will be somewhat less than 316 but way better than carbon steel.

If you do use these shims, a greater concern is sealing them to the shaft to exclude water from the shim/shaft gap. Corrosion resistant steels rely on a thin surface film which fails if wet without oxygen. Make sure they are well sealed to keep water out.

I don't have any personal experience with these shims in this environment, so can't say how well they work, but my instinct is to try to move the seal contact area over, or have the shaft chromed (chrome being the key element in stainless steels).

Another 2 cents worth...
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Old 15-10-2011, 17:53   #35
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Re: Saildrive Prop Shaft Repair

Quote:
Originally Posted by rolandcavanagh View Post
"Stainless" steel (formally "corrosion resistant") comes in many alloys, and only the 300 series exhibits non-magnetic behavior, however, if a 300 series is cold worked (rolled, bent, etc) or welded it becomes somewhat magnetic. Typical boat stuff is 316, and parts are usually stress relieved to improve corrosion resistance, so they typically won't respond to a magnet. 300 series is also relatively soft. We have a set of kitchen knives that hold an edge, are very stiff, and very magnetic, yet corrosion resistant. I'll bet they are 440C, an alloy that is tough and can be hardened.

Long story, the point is that the shims are probably either an alloy that can be hardened for wear resistance, or are a 300 series that have been cold worked. Either way they can be magnetic and their salt water corrosion resistance will be somewhat less than 316 but way better than carbon steel.

If you do use these shims, a greater concern is sealing them to the shaft to exclude water from the shim/shaft gap. Corrosion resistant steels rely on a thin surface film which fails if wet without oxygen. Make sure they are well sealed to keep water out.

I don't have any personal experience with these shims in this environment, so can't say how well they work, but my instinct is to try to move the seal contact area over, or have the shaft chromed (chrome being the key element in stainless steels).

Another 2 cents worth...
Roland, Thanks for the great education on different types of stainless. I'm going to call Speedi-sleeve company and ask what type of stainless they are using. I'm tempted to put one in salt water to see if it rusts, but then I can't return it for a refund.
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Old 14-06-2012, 02:51   #36
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Re: Saildrive Prop Shaft Repair

Hi
I've been following this thread with interest as I have the same problems . I have the SD20 yanmar saildrives and because of complications in a remote place I cant measure the prop shaft size were the seals sit! Does anyone know what the prop shaft diameter should be at the oil seals or what size speedi sleeves they have used?? Any help would be great thanks
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Old 14-06-2012, 07:05   #37
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Re: Saildrive Prop Shaft Repair

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Hi
I've been following this thread with interest as I have the same problems . I have the SD20 yanmar saildrives and because of complications in a remote place I cant measure the prop shaft size were the seals sit! Does anyone know what the prop shaft diameter should be at the oil seals or what size speedi sleeves they have used?? Any help would be great thanks
I don't have the diameter you need, but I had the same problem when I decided to buy speedi-sleeves. I don't know whether your Yanmars have the same configuration as my Volvos, but I was able to measure the shaft diameter with the prop removed, but without removing the seals. Also, if you have a replacement bearing for the shaft that fits over the same area as the seals (Volvo does), you can measure the inside diameter of the bearing to give you a very close measurement of the outside diameter of the prop shafts. Good luck.
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Old 14-06-2012, 07:47   #38
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Re: Saildrive Prop Shaft Repair

When we had our main engine transmission repaired there was scoring on the shafts from damaged bearings. This was repaired by a West coast shop that specializes in this type of work. They coat the steel with ceramic to make it even better than new!!
For info call Peter at Nopper Marine in Fairhaven, MA on 508-993-5050. He is a good guy and may be able to refer you to the right place.
Chris
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Old 14-06-2012, 08:48   #39
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Update on Saildrive Prop Shaft Repair

Thanks Top Secret for reminding me to update this thread.

When I hauled out last November I was a victim of "paralysis of analysis" and didn't even remove the prop shafts to look at them. After discussing this with a few experienced cruiser friends they all suggested, "if it ain't broke don't fix it." When I drained the oil out of the sail drives, it was clear and no sign of water. I did buy a set of speedi-sleeves and was prepared to put them in if the oil looked bad. Since the haulout we made a trip to the Bahamas and put another 200 hrs on the drives and they still don't appear to have any water intrusion. I just sent off oil samples for analysis to see if there are very small amounts of water that I can't see.

I know I'm on borrowed time and eventually the seals will leak, but I'm hoping to get one more cruise in before the next haulout and take care of the problem next year. I still have not decided how to fix the scoring in the shafts. I'm leaning toward putting in the speedi-sleeves and just replace them every haulout. I think it's likely they would hold up for about 400 hrs of use before wearing through. Anyone out there using speedi-sleeves in seawater? If so, how is it working out?
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Old 14-06-2012, 08:50   #40
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Re: Saildrive Prop Shaft Repair

These pictures may help
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Old 14-06-2012, 09:24   #41
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Re: Saildrive Prop Shaft Repair

Wow! That's just what I needed, Cotemar.

Have you figured out how many hours you will get on the speedi sleeves? Am I correct that you used the "gold version" of speedi sleeves?
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