Coupling back on to prop shaft

Dubo

.
Oct 26, 2010
84
Hunter 340 Deltaville Va
Does anyone know how the coupling is fitted on the prop shaft? Interference fit or tapered? After installing a new PSS, I am at the point of slipping the coupling on the shaft. I have done this before successfully, but it was a replacement, not a new PSS install. I'm not sure if that shaft was wet sanded until the coupling went on. This install is replacing a stuffing box, so this coupling/shaft has never been touched. I don't want to take a hammer to the prop end and drive the coupling on due to potential damage to the tranny. Is there a safe way to get the coupling on? A press is out of the question, obviously. Has anyone had success with heat? If so, what was your method? Is wet sanding(400-600) and heat the way to go? May be some PB??? Can the tranny take some modest blows if cushioned with wood?
Engine is a Yanmar 3GM.

12/01/20 - My solution:
I honed the interior of coupling real shiny and cut a 2x4 to the length of the engine well(fore of engine drip pan to start of tranny flange). Lubed the shaft and coupling with teflon. Using the aft end of the 2x4 for leverage, I then placed a flat steel bar(90 degree to 2x4) against it's end. I was able to bang the coupling on without any contact with the tranny. The bar against the 2x4 absorbed the impact of banging the coupling on the shaft without any contact to the tran flange. I did use a block of wood on the prop end of the shaft when driving the coupling on. I hope this helps anyone else having trouble reinstalling a coupling on the shaft.
 
Last edited:
Nov 22, 2011
1,192
Ericson 26-2 San Pedro, CA
Does anyone know how the coupling is fitted on the prop shaft? Interference fit or tapered? After installing a new PSS, I am at the point of slipping the coupling on the shaft. I have done this before successfully, but it was a replacement, not a new PSS install. I'm not sure if that shaft was wet sanded until the coupling went on. This install is replacing a stuffing box, so this coupling/shaft has never been touched. I don't want to take a hammer to the prop end and drive the coupling on due to potential damage to the tranny. Is there a safe way to get the coupling on? A press is out of the question, obviously. Has anyone had success with heat? If so, what was your method? Is wet sanding(400-600) and heat the way to go? May be some PB??? Can the tranny take some modest blows if cushioned with wood?
Engine is a Yanmar 3GM.
Others will no doubt weigh in, but I think I'd use the opportunity to replace it with a split coupling. That will make future removal and reinstallation much easier.

Here's the one I plan to get for my little 1GM.
 

dmax

.
Jul 29, 2018
971
O'Day 35 Buzzards Bay
The coupling uses an interference fit - I used a split coupling which I was able to tap on with the coupling disconnected from the transmission. The transmission should not be the recipient of any hammer blows, even if cushioned by wood, you can damage the bearings. Read this article from MaineSail before proceeding:
 
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Likes: Alan Gomes
Mar 6, 2008
1,078
Catalina 1999 C36 MKII #1787 Coyote Point Marina, CA.
For my new coupler, to insert the shaft we used wood mallet from propeller end. The transmission can take soft blows with no damage.
 

Dubo

.
Oct 26, 2010
84
Hunter 340 Deltaville Va
The coupling uses an interference fit - I used a split coupling which I was able to tap on with the coupling disconnected from the transmission. The transmission should not be the recipient of any hammer blows, even if cushioned by wood, you can damage the bearings. Read this article from MaineSail before proceeding:
The split coupling may be a good option. Did you have any alignment issues with the split coupling? I'd hate to have one solution spawn a new issue.
I will also review MaineSail link. Thanks!
 
Jan 22, 2008
1,654
Hunter 34 Alameda CA
The split coupling may be a good option. Did you have any alignment issues with the split coupling? I'd hate to have one solution spawn a new issue.
I will also review MaineSail link. Thanks!
I used a split coupling for the ease of removal. Except the shaft hole was .007 inch off center from the flange bolt pattern. That lack of concentricity caused my cutless bearing to fail because of the shaft wobble. Then it wobbled so much that the cutless became loose in the strut even with setscrews resulting in it spinning and enlarging the bore. I didn't have time to replace the strut at that time so I bonded the new cutless in with 5200. After about 12 hours the rubber insert inside the cutless broke its bond to the bronze sleeve and extruded out. We lost an entire season of sailing and had to haul again. The best thing to do if you go that route is to have a machine shop fit and face the coupling and check the runout. You want to make sure it is perfectly aligned.
 
Jul 7, 2004
8,402
Hunter 30T Cheney, KS
I had a difficult time finding a machine shop to fit and face my new coupling to my shaft. We are landlocked and not very marine oriented. I ended up sharing several videos on the process to the guy willing to do it.
 

dmax

.
Jul 29, 2018
971
O'Day 35 Buzzards Bay
The split coupling may be a good option. Did you have any alignment issues with the split coupling? I'd hate to have one solution spawn a new issue.
I will also review MaineSail link. Thanks!
The split coupling did not cause any alignment issues - it's not split in two pieces but is split along half its length. You should definitely have it fit and faced before installing.
 
Jul 1, 2010
962
Catalina 350 Lake Huron
Definitely read the Mainesail article mentioned above. Now is the time to pull the shaft and have a new coupling fit and faced to it rather than find out you should have done that later. How's the cutless bearing, anyhow. Just call me the bearer of project creep...
 
Jul 7, 2004
8,402
Hunter 30T Cheney, KS
Definitely read the Mainesail article mentioned above. Now is the time to pull the shaft and have a new coupling fit and faced to it rather than find out you should have done that later. How's the cutless bearing, anyhow. Just call me the bearer of project creep...
The hardest part, getting the coupling off, is done. It's a good time to replace the bearing if it hasn't been done in a long while. You'll also find out if your shaft is straight when you fit and face it.