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Old 05-31-2021, 06:38 PM   #41
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[QUOTE=sbman;1007408]Here is a picture of the shaft collar in action. I was trying to remove a stuffing box that was extremely stuck. I used the shaft collar as a hardpoint to pull from, it clamps on the shaft and does not mar it. It could be used to pull on the drive coupler to pull it onto the shaft with appropriate hardware employed.

That is a super slick set up and great idea. Thanks for posting. Will put it in the “Get’er done” rolodex.
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Old 05-31-2021, 06:43 PM   #42
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My starboard driveshaft slid completely out of the coup0ler and luckily the rudder stopped it from going to the bottom. Found a couple of sheared bolts lying in the bilge. It appeared that several bolts loosened and then the remaining bolts sheared. a local marine mechanic was able to pull the drive shaft back in using a chain come-along and then a pipe wrench to orient the driveshaft. Quick trip to hardware store for six new number 8 bolts and back in service in 3 hours. Checked port side and found loose bolts there. Bolt check is now on my annual checklist.
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Old 05-31-2021, 11:16 PM   #43
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Even if it is slid right home, it's still only the split part that does the clamping and carries the drive. Not sure why you think it's going to suffer cracking if shaft is straight & in line. If it's not, there is stress anyway, fully home or not.
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Old 06-01-2021, 12:09 AM   #44
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My split couplers have the shaft slid almost all the way onto the coupler. The couplers are short about 1/4” from being all the way onto the shafts. It is a little tough in the photo to see but the shaft is almost all the way into the coupler, not just the split part in the rear.
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Old 06-01-2021, 01:51 PM   #45
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Originally Posted by Nautica View Post
Even if it is slid right home, it's still only the split part that does the clamping and carries the drive. Not sure why you think it's going to suffer cracking if shaft is straight & in line. If it's not, there is stress anyway, fully home or not.
Nautica, There is always a degree of vibration on the shaft, but what is important is that the end point of the vibration not be before or at a 'stress riser' point, such as the end of the split of the coupling. That would magnify the vibrational stress to the corners of the split, where the vibration has to change direction at the inside corners.

Getting the shaft tail end to bed after the split moves the stress riser point up into the solid part of the coupling, where it dissipates further.
More information: https://www.sciencedirect.com/topics.../stress-raiser
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Old 06-01-2021, 02:04 PM   #46
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Quote:
Originally Posted by Comodave View Post
My split couplers have the shaft slid almost all the way onto the coupler. The couplers are short about 1/4” from being all the way onto the shafts. It is a little tough in the photo to see but the shaft is almost all the way into the coupler, not just the split part in the rear.
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Nautica, There is always a degree of vibration on the shaft, but what is important is that the end point of the vibration not be before or at a 'stress riser' point, such as the end of the split of the coupling. That would magnify the vibrational stress to the corners of the split, where the vibration has to change direction at the inside corners.

Getting the shaft tail end to bed after the split moves the stress riser point up into the solid part of the coupling, where it dissipates further.
More information: https://www.sciencedirect.com/topics.../stress-raiser
Exactly, stress points at cuts, dings, scratches, etc... all the same reasons you smooth out a scratch on any piece of metal subject to high stress, a scratch or sharp edge can be the location where a crack begins to form. Machined components will have all of their edges deburred and smoothed to remove stress risers. There are a lot of forces involved and the shaft coupling suffers through them all, all sorts of vibrations, twisting forces which vary a lot each rotation of the engine. It's certainly not guaranteed to form a crack, but installed incorrectly there is a greater risk of that type of failure.

Now that the OP has discovered that the shaft is actually inserted fully, and has dimples to prevent the shaft from sliding in/out of the coupler, there's not much to be concerned about.
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Old 06-01-2021, 02:09 PM   #47
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There should be a couple inches between the Cutless Bearing and the prop to allow water to flow freely through the bearing as that is what keeps it lubricated.
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Old 06-01-2021, 02:21 PM   #48
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There should be a couple inches between the Cutless Bearing and the prop to allow water to flow freely through the bearing as that is what keeps it lubricated.
Absolutely. That is why he needs to see if there is enough shaft to pull forward and engage the coupler fully. If not then time to have a spacer made.
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Old 06-01-2021, 03:53 PM   #49
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Now that the OP has discovered that the shaft is actually inserted fully, and has dimples to prevent the shaft from sliding in/out of the coupler, there's not much to be concerned about.
Yup. Thanks again everyone - even though the problem turned out to be a false alarm I have learned a ton from this thread. Pinch bolts came in from McMaster-Carr today so I'll put 'em in shortly and re-torque every faster on the prop shafts.
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