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10-03-2016, 08:32
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#1
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Registered User
Join Date: Sep 2014
Location: Sandy Point Wa
Boat: Clark, San Juan 30
Posts: 25
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Transmission to Prop shaft
Greeting My Fellow Sailor's I have a problem that with the Vast Knowledge on this site I have learned a whole lot. Your Guidance and Help with this will be Greatly appreciated So Here is my problem I have a 1inch shaft on the prop end and it has a 3 bolt pattern with a 3inch between bolts and the Transmission has a flex flange that is a 4 bolt pattern with 3inch between bolts
Every thing else is all good what do I need to do that will make the most sense replace the shaft flange or replace the flex coupler with a 3 bolt flange I am tight on cash due to the cost of installing the engine the haul out and the dry pad for the work to be done on I would welcome any and all Idea's on what step I should do with the least amount of cost involved also least amount of labor I surely welcome any Answers
Thank You SV UsCa Jack
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10-03-2016, 08:35
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#2
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Registered User
Join Date: Aug 2006
Location: Skagit City, WA
Posts: 25,453
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Re: Transmission to Prop shaft
3 bolt is a bit unusual, get a 4 bolt coupler that matches your engine/coupler flange.
BTW, do not use nylok nuts on the bolts. Use conventional lock washers and good quality, higher grade than basic bolts and nuts.
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard
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10-03-2016, 08:40
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#3
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Registered User
Join Date: Sep 2014
Location: Sandy Point Wa
Boat: Clark, San Juan 30
Posts: 25
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Re: Transmission to Prop shaft
Thank you so I should pull the shaft and replace the Shaft flange and make sure I use grade 8 bolts
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10-03-2016, 08:49
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#4
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Registered User
Join Date: Mar 2011
Location: Nova Scotia Canada
Boat: Wharram Tiki 46
Posts: 1,321
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Re: Transmission to Prop shaft
Quote:
Originally Posted by Cheechako
3 bolt is a bit unusual, get a 4 bolt coupler that matches your engine/coupler flange.
BTW, do not use nylok nuts on the bolts. Use conventional lock washers and good quality, higher grade than basic bolts and nuts.
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Why not Nyloks ?
Just bought an R&D shaft saver type coupling and it came with Nyloks.
I understand that they are one time use in a critical application like this, but is there a technical reason not to use them ?
Cheers,
JM.
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10-03-2016, 08:50
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#5
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Registered User
Join Date: Aug 2006
Location: Skagit City, WA
Posts: 25,453
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Re: Transmission to Prop shaft
You have to pull the flange to remove the shaft anyway... so no need to remove the shaft... just the flange with a puller.
As long as you have it off though, slide the shaft back and look at the surface of the shaft where it resides in the packing/cutlass bearing... they are often corroded from sitting with stagnant moisture in there, and tend to tear up the packing that way.
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard
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10-03-2016, 08:57
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#6
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Registered User
Join Date: Aug 2006
Location: Skagit City, WA
Posts: 25,453
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Re: Transmission to Prop shaft
Quote:
Originally Posted by NahanniV
Why not Nyloks ?
Just bought an R&D shaft saver type coupling and it came with Nyloks.
I understand that they are one time use in a critical application like this, but is there a technical reason not to use them ?
Cheers,
JM.
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So…. While on the hard in Trinidad, I decided to clean up the rusty coupling, repack the stuffing box, realaign the engine etc. Got it all done and decided on new bolts and Nyloks. It was all properly tight and secure. After less than 8 hours of use I heard this loud rattling while motoring. One of the 4 bolts was completely gone. The other 3 were almost off, the holes in the coupling were damaged etc. Proceed accordingly! Your choice. My theory is the heat of the engine application softens the nylon.
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard
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10-03-2016, 09:09
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#7
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Registered User
Join Date: Mar 2011
Location: Nova Scotia Canada
Boat: Wharram Tiki 46
Posts: 1,321
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Re: Transmission to Prop shaft
Quote:
Originally Posted by Cheechako
So…. While on the hard in Trinidad, I decided to clean up the rusty coupling, repack the stuffing box, realaign the engine etc. Got it all done and decided on new bolts and Nyloks. It was all properly tight and secure. After less than 8 hours of use I heard this loud rattling while motoring. One of the 4 bolts was completely gone. The other 3 were almost off, the holes in the coupling were damaged etc. Proceed accordingly! Your choice. My theory is the heat of the engine application softens the nylon.
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OK, you had a bad experience with nyloks, but, spring washers from questionable sources can be bad as well. I don't think your experience should mean never to use nylocks.
Perhaps a better take-away from your experience would be to monitor newly installed equipment in the first few minutes of operation then after a few hours, then days, then yearly.
Cheers,
JM.
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10-03-2016, 09:19
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#8
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Registered User
Join Date: Aug 2006
Location: Skagit City, WA
Posts: 25,453
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Re: Transmission to Prop shaft
Yeah, I hear you. But sometimes I've found "if it aint broke, don't fix it!" is a great policy!
Still, the heat thing makes me nervous, but I think some people have used them successfully.
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard
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10-03-2016, 09:50
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#9
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Registered User
Join Date: Mar 2009
Location: Homer, AK is my home port
Boat: Skookum 53'
Posts: 4,042
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Re: Transmission to Prop shaft
I've never had any problems with Nyloks backing off. I use them on many different applications. I too recommend that you change the shaft flange, to 4 bolt unit; that is the standard of the industry.
__________________
" Wisdom; is your reward for surviving your mistakes"
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11-03-2016, 07:36
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#10
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Senior Cruiser
Join Date: Oct 2007
Location: 29° 49.16’ N 82° 25.82’ W
Boat: Pearson 422
Posts: 16,306
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Re: Transmission to Prop shaft
I bought new grade 8 bolts for my shaft flange and the local fastener store recommended an all steel locknut. No nylon insert. Sorry but I don't recall the name or brand but they're out there.
__________________
The water is always bluer on the other side of the ocean.
Sometimes it's necessary to state the obvious for the benefit of the oblivious.
Rust is the poor man's Loctite.
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11-03-2016, 08:23
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#11
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Registered User
Join Date: Jan 2016
Posts: 13
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Re: Transmission to Prop shaft
The 4 Shaft coupling bolts on my Ranger 33 are lockwired together to prevent loosening. Small engines with few cylinders put out a nasty cyclic rotary vibration which can readily loosen nuts and bolts. 316 stainless bolts and nuts with lockwire holes are available from McMaster-Carr at good prices
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11-03-2016, 09:28
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#12
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Registered User
Join Date: Dec 2008
Location: SC
Boat: None,build the one shown of glass, had many from 6' to 48'.
Posts: 10,208
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Re: Transmission to Prop shaft
Quote:
Originally Posted by Chevy1217
Greeting My Fellow Sailor's I have a problem that with the Vast Knowledge on this site I have learned a whole lot. Your Guidance and Help with this will be Greatly appreciated So Here is my problem I have a 1inch shaft on the prop end and it has a 3 bolt pattern with a 3inch between bolts and the Transmission has a flex flange that is a 4 bolt pattern with 3inch between bolts
Every thing else is all good what do I need to do that will make the most sense replace the shaft flange or replace the flex coupler with a 3 bolt flange I am tight on cash due to the cost of installing the engine the haul out and the dry pad for the work to be done on I would welcome any and all Idea's on what step I should do with the least amount of cost involved also least amount of labor I surely welcome any Answers
Thank You SV UsCa Jack
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You might ask a machine shop. Even a rough sketch will probably give them an idea and let you know what to bring them and probably the cost. Pic might help but go with a sketch that has measurements.
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11-03-2016, 09:50
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#13
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Registered User
Join Date: Mar 2015
Location: NC
Boat: Cheoy Lee OS 41 ketch
Posts: 26
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Re: Transmission to Prop shaft
Nylon nuts can have a heat problem with the nylon insert melting. Correct use is dependent on location and temperature of heat. Use distorted thread all metal locknuts. Been used in aviation and race cars for years. Strength and metal rated for applications. Most good nut and bolt suppliers will have them in stock,
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11-03-2016, 10:03
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#14
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Registered User
Join Date: Dec 2008
Location: SC
Boat: None,build the one shown of glass, had many from 6' to 48'.
Posts: 10,208
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Re: Transmission to Prop shaft
Quote:
Originally Posted by Cadence
You might ask a machine shop. Even a rough sketch will probably give them an idea and let you know what to bring them and probably the cost. Pic might help but go with a sketch that has measurements.
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Quoting myself!
PS, replacing the shaft flange will be cheaper than the flex..
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11-03-2016, 10:04
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#15
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Moderator Emeritus
Join Date: Oct 2013
Location: Jacksonville/ out cruising
Boat: Island Packet 38
Posts: 31,351
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Re: Transmission to Prop shaft
Castellated nut and a cotter pin is the standard for aircraft on parts that are subject to rotation, but I think most boats out there have regular nuts and spit lock washers.
I won't use self locking nuts on SS fasteners though, SS galls so bad that without anti-seize they often seize, and if your anti-seizing self locking fasteners, it seems to defeat the point?
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