Forums, Engine, Gearbox, Stern Gear, etc, cutlass bearing

NickVBaker at 03/04/2012 20:26:54
Just before I get something wrong, would anybody be kind enough to tell me the specification of cutlass bearing I need and where to get it from. I’ve extracted the shaft and its 24.7mm at the bearing. Is this too worn? Its very polished and got some deeper grooves. I measured the unworn shaft between the seal and the engine coupling and it was about 24.85. So although it looks a bit dramatic, the wear is quite slight – isn’t it. Or is it?

I’ld be very grateful for some comments.

Nick Baker
French herring

George Isted at 04/04/2012 10:00:47
Doesn’t sound too bad to me. My shaft was a little worn last time I pulled it out but I don’t have any vibration or knocking. The most important thing is to check the alignment of the engine/shaft as misalignment is the cause of most noise/wear problems. Ideally alignment should be checked/adjusted with the boat in the water although it is not essential.

Alan Dixon at 07/04/2012 15:38:01
The Shaft is 1" and the prop tube is 1 1/4" that’s the spec of the cutlass they can be purchased from T Norris http://www.tnorrismarine.co.uk/ look at http://www.tnorrismarine.co.uk/bearings.php code W101

NickVBaker at 07/04/2012 22:03:22
Dear George and Alan

Thank you very much for your helpful and prompt replies.

Best wishes

Nick

GlennG at 09/04/2012 00:06:03
It’s definitely 1" and not 25mm?

I measured my shaft and found it was 25mm. It was replaced three years ago.

As it happens my cutlass bearing’s already warn out with about 3mm of play in the vertical direction. I’m having it and the seal replaced this week.

Alan Dixon at 09/04/2012 09:02:45
As I understand it the original shafts were 1" (25.4mm) at I do not see a 25mm x 32mm bearing for sale at T Norris.
Beware of mixing a metric shaft with an imperial bearing you will build in 0.4mm play at the start.
I last replaced the Cutlass 2005, and when checked last year was still in good condition with 1100 hours use behind it

NickVBaker at 10/04/2012 09:12:45
Before I order from Norris, and thinking about George’s comment about alignment, does anyone have any experience of using an R&D Flexible Coupling. They make one for the Yanmar for about £70 – seems good value to me. Also, while I’ve got my credit card out, should I replace their deep sea seals?

George Isted at 10/04/2012 10:02:11
Concerto has a R&D Flexible Coupling, this probably helps quite a bit as the 2GM being a 2-cylinder does shake about a fair bit at tickover. I can’t tell you if it made a difference to wear or noise but I have not(touch wood) had any problems with the sterngear.

NickVBaker at 10/04/2012 10:54:05
Thank you, George. I guess I would have to shorten the shaft by the length of the coupling (32mm) this could have the beneficial effect of moving the slightly worn part partially out of the cutlass bearing – what do you think?

George Isted at 11/04/2012 11:57:50
Sounds like a plan to me.

Remember to put a small piece of earthing wire between the two metal parts of the coupling to ensure your hull anode is connected to the prop (not a problem if you have a darglow feathering prop with it’s own anode).

GlennG at 11/04/2012 22:06:59
For what it’s worth, Perle has an Aquadrive between the shaft and 2GM20. Still hasn’t stopped the cutlass bearing wearing!

GlennG at 12/04/2012 16:49:18
I’ve just been told that the type of ‘cutlass bearing’ fitted to Contessa 32’s are prone to a certain amount of wear which settles down after a while.

My bearing has about 3mm of vertical movement, but negligible sideways movement. Is this normal?

Also, where do we source these bearings?

waratah912 at 12/04/2012 22:49:56
If it’s the original Tufnol type bearing, Jeremy R will supply you one. We were changing these regularly until I replaced the shaft about 5 years ago and haven’t had any trouble since still virtually no play. Cost of the shaft was only about 50% more than the bearing so definitely a good investment. Seems that the wear in the shaft was signficantly reducing bearing life.

GlennG at 13/04/2012 00:37:40
Rats. The shaft was replaced only three years ago with the ‘new’ bearing.

I’ll call Jeremy tomorrow to get a replacement.

Alan Dixon at 13/04/2012 08:48:51
When I re engined Charlotte (2005) the Engineer who helped me advised that the Tufnol bearing was suitable for the 12 hp Petter, but not for the 25 hp Vetus. He advised a standard cutlass water fed from the deep sea seal that we also fitted at the time. This thread leads me to the thought that perhaps he is right and the tufnol is not up to the 20 + hp engines we are now sporting now. Any other thoughts?

GlennG at 14/04/2012 01:56:50
I spoke to Fiona earlier. The Tufnol bearings are in stock for £68+VAT. Important to know if the shaft is 25mm or 25.4mm. I thought I’d measured it as 25.1mm, i.e. 25mm with some tolerance. Now I’m not so sure so I’ll measure twice:-)

As the rudder’s off for the bottom bracket and the stern gland is being replaced with a PSS, I may as well change the bearing.

A thought about the higher HP engines; we’d probably not use the higher power as there’s the hull speed to contend with and that’s that. The main thing is a decent three bladed prop. Since fitting the current 3 bladed 13.5 × 13 the engine won’t overrev and she’s pushed along nicely at just over 6kts flat out and 5.3 for an easy life. And that great kick to port in astern; terrific for maneuvering (her specialty is her ‘handbrake turn’ to starboard).

NickVBaker at 14/04/2012 17:43:35
HELP! Nothing is as it seems!

Went down to French Herring today armed with studding and washers to extract old cutlass and found (1) the internal diameter of the inbord end of the tube is much less than 1.5"so I couldn’t get the washer down, and (2) investigating the other end, I found that the neoprene insert is only 2" long INSTEAD OF 4", and that there is no edge of the brass housing for as far back as I can detect with a piece of wire.

And (3) the shaft emerges from what looks like a brass insert (presumably the cutlass housing) let into a bronze flange with two set screws into the skeg. No sign of any other grub screws etc.

This seems to be all a bit non-standard to me.

PS There is a Volvo seal on the inboard of the tube with an ID of about 45mm.

moongirl at 14/04/2012 18:09:00
Nick
sounds like you have the ‘old’ style shaft tube. Are the set screws one above and below the shaft outlet & parallel to the c/l of the boat? Have a look at my drawing in the Technical section – it shows the earlier bronze shaft tube arrangement with the Tufnol bearing pushed into the end.
I think our former Magazine Editor Annie used a bit of broom handle to knock the Tufnol bearing out of the tube (from the inside)

NickVBaker at 14/04/2012 18:40:03
Dear Colin – thank you for your quick reply.

Yes, it is a flange as in type A, but it isn’t a tuffnol bearing but a short cutlass bearing (2"). And, the other mystery, is that I couln’t use Annie’s broomstick because (a) I couldn’t get it into the tube at the inboard end, and (b), there is no “edge” to the cutlass bearing housing to engage with the broomstick. It seems that the stern tube might have a short length where the diameter is greater to house the tufnol bearing, and maybe a special cutlass bearing has been used.

Should I undo the set screws and try to remove the whole tube?

By the way the boat was built in 1977 – no 540, and she has spent most of her life in France (which could account for anything!

moongirl at 14/04/2012 19:12:52
Nick
I think the bronze tube is bonded in QED not a good idea to remove it!
Do you have a scanner so you can sketch your arrangement and e-mail to me to have a look. colinking@talktalkbusiness.net
It seems that somebody might have pushed a bronze/‘rubber’ type cutlass bearing into the tube & its held in by the plate which is screwed into the hull.

NickVBaker at 14/04/2012 20:01:51
Hello Colin

Will send some diagrams tomorrow. Thank you so much for your help. I don’t think the plate is holding the bearing in, because i can quite clearly see the end of the brass tube holding the cutlass, surrounded by the bronze coloured flange. But I hope my diagrams will make it clearer.

Nick

GlennG at 15/04/2012 14:43:43
Does it look like this? From CO548



The two screws were removed prior to the photo along with the filler between the skeg and flange. The flange is solidly attached to the stern tube.

moongirl at 15/04/2012 21:07:27
From the sketch e-mailed to me earlier by Nick it would seem that the arrangement is similar. Its the earlier fitting as per my drawing in the Technical Section ie bronze tube with the plate plus set screws. Nick’s problem seems to be that someone in times gone past has drilled out part of the bronze tube and fitted a bronze/brass + neoprene cutlass bearing to replace the Tufnol bearing – as a result Nick is having problems removing the bearing as there is no step to drift out and nothing to get hold of with a pair of Mole Grips. I have suggested a Dremel cutter or one of those hacksaw blades held in a handle such that the blade sticks out allowing a cut to be made. Any other thoughts folks?

waratah912 at 15/04/2012 21:51:25
Hmmmm…..head scratching time!!
If the shaft tube has been modified, then before trying to remove the exisiting bearing, I’d check to see if I can get a replacement. If so, ok go ahead and cut out the existing, though if it’s been recessed into the shaft tube, sawing it out is going to be difficult without making cuts further up the tube, so back to a Dremmel type tool and grind slots at 18o degrees.
If no replacement is available then consider a custom made tufnol bearing turned to either the id of the exsting brass housing of the cutlass bearing and just remove the neoprene, or to the od and remove the whole bearing, but in this case sounds like it would be only 2" long?

NickVBaker at 16/04/2012 08:52:46
Thank you for all your responses.

Its not quite like GlenG’s photo because there is no Tuffnol (or any other material) protruding aft of the rectangular flange attached to the stern tube. I.e it is flush and looking direct on to it you can see (from inside outwards) the neoprene insert, then the brass housing, and finally the bronze flange

waratah912 at 22/04/2012 09:25:10
Off the wall thought – if you could make up a splined shaft to mate with the slots in the neoprene, you might be able to break the friction by rotating the bearing within the yube, once turning you may be able to “unscrew” it.

moongirl at 22/04/2012 11:17:49
Waratah’s suggestion makes some sense but potentially a bit expensive if it doesn’t work!
Of course you will still have the same problem in the future if you need to change the bearing again plus the bearing length will be less than normal. Perhaps the solution’ once the old one is extracted, would be to
revert to a purpose turned Tufnol unit held by screws through the side of the skeg and fitted with an external step that could be gripped with Moles if it needed to be replaced. If there is any ‘wobble’ in the shaft then the Tufnol would wear rather quickly!

Regards

Simon Begley at 22/04/2012 12:42:28
When we owned Milly Brown I removed the stern tube to get the cutlass bearing out. Once the two bolts were removed it slid out quite easily and I knocked the old Tufnol bearing out using a broom handle as a drift. Only the aft 50mm or so of the stern tube was machined internally, so to fit a brass and neoprene bearing (which was longer than the original Tufnol one) I machined the forward end down until it would fit inside the un-machined section of the stern tube.

We then did a summer in the Western Med, and motored back through the French canals and it was still ok when we got home!

NickVBaker at 22/04/2012 14:24:59
Thank you, Simon for that info.

I undid the two set-screws and tried to prize the flange away from the skeg, but it seemed very reluctant to part company. I got the impression that it was bonded in, but if so, why the set screws?

What you say about the machining makes sense to me, because I had already concluded that the ID of the tube was considerably less than the 1 1\2 " which is the OD of the cutlass bearing. Mine has had a short cutlass bearing forced in (with no apparent way of pulling it out) – I guess to replace the tufnol bearing.

I’ll get a bit more physical with the flange the next time.

Thanks

NickVBaker at 22/04/2012 14:45:35
Thank you Colin and Watarah.

The cutlass bearing is a rather pathetic affair; the neoprene is much thinner than on the one I have bought from Norris (and the yellow brass housing is much thicker), and the neoprene is worn, so I doubt it would take much torque. I drilled two 5mm holes on the diameter, close to the aft end of the tube and made a tool out of steel rod which engaged in them, and tried to pull and turn. But nothing budged.

I am beginning to think that I should bore it out in situ. But I think the tube is only about 30mm ID and 4mm wall thickness, which would mean I would cut the tube right away where bearing is. That doesn’t sound like a good idea to me. Did the earlier boats have a narrower tube?

Jeremy and Fiona at 31/05/2012 20:43:00
Or you could quite simply come to the original builder of your boat, who supplies all sorts of spares including cutless bearings!!!

NickVBaker at 07/06/2012 13:46:56
Thank you, Jeremy and Fiona, actually that’s what I did do. The reason for my uncertainty is that I found that it was an old type 1 1/4 " ID tube, with a thin wall cutlass bearing. So I thought I should replace it with one, but after discussion with one of your people, I replaced it with a tufnol bearing. It is now all running sweetly.

Thank you too to George and all the others who kindly offered advice.

Nick Baker – French Herring