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05-13-2016, 04:13 AM
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#1
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Senior Member
City: Perth
Join Date: Jul 2014
Posts: 374
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Cutlass Bearing - how tight a fit -new
Bought a Cutless bearing 1'' x 1 1/4" x 4" slipped it over the shaft and it was real sloppy, all along the shaft. - barely tighter than the old worn one. Thought, oh yeah the shaft's metric then. Went and bought a metric cutless - 25mm x 1 1/4" x 4" slipped it on and felt it tighten as I pushed it on and thought great - then it split length ways. WTF
So question is, how tight are NEW cutless bearings, I read somewhere that you need to freeze them first to get then on ?? If so, cutless bearings are quite tight fitted new.
Thinking - maybe I can just epoxy this into the housing and then slip it on the shaft and discount the fact it cracked/split. After all, the epoxy will fill the crack and it's nice and firm and glued into a housing and going nowhere.
P.S.The shaft is not worn as I moved the cutless along the shaft well beyond the point were it is mounted and felt no difference in resistance.
regards Brett
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05-13-2016, 06:20 AM
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#2
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Guru
City: Ft Pierce
Vessel Name: Sold
Vessel Model: Was an Albin/PSN 40
Join Date: Oct 2011
Posts: 28,149
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Snug.....but not so tight it takes more than some twisting to slide it on.
Why it split is beyond me...but I have never used a composite one...was this one bronze bodied or composite?
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05-13-2016, 07:18 AM
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#3
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Senior Member
Join Date: Sep 2015
Posts: 204
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This link provides a good technical discussion. Allowable wear/clearance guideline is on page 20. For 1-2 inch shafts their number is .04".
http://www.duramaxmarine.com/pdf/Dem...StaveBroch.pdf
I wouldn't advise gluing the bearing into the hull.
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05-13-2016, 07:40 AM
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#4
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Guru
City: Sarasota/Ft. Lauderdale
Join Date: Apr 2014
Posts: 5,438
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It should not be a sloppy fit. In fact it should be a press fit where freezing the bearing, if it's a metal one, can make it easier to slide it in.
Bearings can be floated and glued in place. Floating bearings need to be propery aligned each time they are changed. But yours is not that type.
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05-13-2016, 08:11 AM
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#6
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Guru
City: Ft Pierce
Vessel Name: Sold
Vessel Model: Was an Albin/PSN 40
Join Date: Oct 2011
Posts: 28,149
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Yes, tight into the strut or bearing carrier....but not onto the shaft and cause it to split.
Now I am not sure exactly what the issue is/was.
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05-13-2016, 09:42 AM
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#7
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Guru
City: Mahón, Menorca
Vessel Name: Halcyon
Vessel Model: 1973 Grand Banks 50
Join Date: Mar 2015
Posts: 521
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Quote:
Originally Posted by bogranjac1
Bought a Cutless bearing 1'' x 1 1/4" x 4" slipped it over the shaft and it was real sloppy, all along the shaft. - barely tighter than the old worn one.
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Was this first bearing in its housing when you slipped it over the shaft? It would be a tighter fit around the shaft if the bearing was inside the housing.
__________________
Gilberto
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05-13-2016, 11:18 AM
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#8
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Guru
City: Cary, NC
Vessel Name: Skinny Dippin'
Vessel Model: Navigator 4200 Classic
Join Date: Jul 2009
Posts: 5,841
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Quote:
Originally Posted by psneeld
Yes, tight into the strut or bearing carrier....but not onto the shaft and cause it to split.
Now I am not sure exactly what the issue is/was.
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Ooops... Right, sorry. Wrong problem.
__________________
2000 Navigator 4200 Classic
(NOT a trawler)
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05-13-2016, 12:37 PM
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#9
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Senior Member
Join Date: Feb 2011
Posts: 305
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I'd measure the shaft. It sounds like you have a 1" shaft, and the 25mm bearing is .015" too small, causing it to split. The bearing must have clearance on the shaft to function, so there is no reason to make the composite body strong enough to resist the force of pushing a "too tight" bearing on the shaft. Once in place the body is supported by the bore of the stern tube or strut.
The composite body has to develop enough compression force in the stern tube to resist moving after pressing in place, and as it is more elastic than bronze it may compress significantly, making the excessive clearance you experienced with the 1" bearing diminish once pressed in place.
Good luck!
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05-13-2016, 01:42 PM
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#10
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Senior Member
City: Perth
Join Date: Jul 2014
Posts: 374
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Island Cessna, your right, got to be a 1" shaft. Maybe the composite material swells slightly on immersion with seawater and/or insertion in the cutless bearing housing and the impression I had of the new bearing being a bit sloppy was misguided.
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05-13-2016, 06:27 PM
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#11
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Guru
City: Brookline, NH
Vessel Name: Shalloway
Vessel Model: Defever 44, twin Perkins
Join Date: Sep 2013
Posts: 2,260
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A new bearing should never be "tight" on the shaft. There always needs to be at least a slight gap for water to act as a lubricant between the two. The composite one that was snug going on and split was definitely too tight on the shaft.
Ken
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05-13-2016, 06:41 PM
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#12
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Guru
City: Sarasota/Ft. Lauderdale
Join Date: Apr 2014
Posts: 5,438
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Quote:
Originally Posted by kchace
A new bearing should never be "tight" on the shaft. There always needs to be at least a slight gap for water to act as a lubricant between the two. The composite one that was snug going on and split was definitely too tight on the shaft.
Ken
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Not exactly true. A new bearing will usually be snug on the shaft to the point that you most likely will need to lube the shaft with soap to get the shaft to slide down the bearings.
The bearing will break in pretty quickly and the space for the water to fill the gap will form pretty quickly as well. If it isn't already there.
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05-13-2016, 07:07 PM
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#13
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Guru
City: Seaford Va on Poquoson River, VA
Vessel Name: Old Glory
Vessel Model: 1970 Egg Harbor 37 extended salon model
Join Date: Jan 2016
Posts: 2,264
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I put in Vesconite bearings. They are some kind of hard plastic.
I put them in 2006, so been 10 years. I hauled out in 2014, there was no wear. none at all.
They are also a lot less money than the bronze bushing with rubber lining.
I did get a crab pot line wrapped the shaft and it dug into the end of the vesconite bushing.
They pressed in after I put them in the freezer. I had taken off the struts, so I did this at the house.
https://www.google.com/search?q=Vesc...hrome&ie=UTF-8
When I ordered these, they came from South Africa by airmail.
they will also custom cut and machine vesconite if you wish
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05-13-2016, 08:06 PM
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#14
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Technical Guru
City: Wilmington, NC
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 6,194
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When I set up my driveline, I bought a new 1 3/4" shaft and new cutlass brgs to fit. With brg in hand it would slip onto shaft with just a hint of clearance, maybe 0.005 to 0.010" guessing. There was a few thou interference in the struts, so the clearance tightened up a bit once pressed in. But still there was some clearance, once all lined up and installed it was an easy roll of the shaft by hand.
If that brg split, it either had a flaw or you beat the heck out of it getting it on.
Something seriously wrong.
Metric shaft 25mm is 0.984"
SAE shaft 1.000" is 25.4mm
16 thou different, more than typical cutlass brg clearance.
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05-14-2016, 05:37 AM
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#15
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Senior Member
City: Perth
Join Date: Jul 2014
Posts: 374
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Semi planning.............at no time did I mention "glueing the cutless into the hull"
Ski in N.C...................I merely pushed the bearing along the shaft I DID NOT "beat the hell out of it"
Although sometimes I feel like "beating my head" against a wall when posters can't read
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05-14-2016, 05:52 AM
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#16
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Guru
City: Mahón, Menorca
Vessel Name: Halcyon
Vessel Model: 1973 Grand Banks 50
Join Date: Mar 2015
Posts: 521
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I understand that what split was the rubber bearing by itself, not the bushing or "housing" it sits in.
Splitting the bushing would take some beating and gluing it to the hull be a really bad idea.
__________________
Gilberto
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05-14-2016, 06:00 AM
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#17
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Guru
City: Ft Pierce
Vessel Name: Sold
Vessel Model: Was an Albin/PSN 40
Join Date: Oct 2011
Posts: 28,149
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I am not sure that is correct either.....I think the composite around the actual bearing split.
And no I would not epoxy it in be a use if it didn't work....tough to fix with a new bearing.
I would try and return the bearing...even if I had to get another first and work the broken one out later.
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05-14-2016, 06:19 AM
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#18
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Guru
City: Mt Crested Butte
Vessel Name: Artemis
Vessel Model: Cheoy Lee 67
Join Date: Feb 2013
Posts: 551
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I would measure accurately the stern tube and shaft, get the correct bearing. Is the sterntube metal or composite? If metal get a metal sleeved bearing. drop in the freezer for a few hours, whip it out rub some washing up lquid on and tap it right in. Taking care to leave at least and inch free on the out side of the tube, to allow for removal of the bearing later in life. The photo appears to show that there may have been an external cutlass bearing at some time? How old is the boat? Composite bearings tend to be on smaller boats and more so sailboats of european extraction.
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05-14-2016, 06:24 AM
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#19
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Guru
City: Mt Crested Butte
Vessel Name: Artemis
Vessel Model: Cheoy Lee 67
Join Date: Feb 2013
Posts: 551
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Also is there any thread visible on the end of the stern tube? I believe I can see where the 2 bolt positions for the external cutlass where in the photos, and if there is thread there then it was set up for the external cutlass arrangement..Another factor is the inset in the deadwood, this was for the lip of the cutlass holder. How much shaft protrudes from the deadwood?
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