Cutlas bearing

[martinriches]

I have just removed the Cutlass bearing form my albin 25.It apears to be brass with a white hard plastic insert .It must be harder than stainless because it has worn the shaft and there is hardly any wear in the plastic. I am curious as to what it is. I am guessing that the brass bearing should press out and I can get a new one machined. It is the first time I have replaced a shaft and bearing and help and advice wil be greatfully recieved. [image]<a href="http://s264.photobucket.com/albums/ii194/martinriches/?action=view&current=P2081389.jpg" target="_blank"><img src="http://i264.photobucket.com/albums/ii194/martinriches/P2081389.jpg" border="0" alt="Photobucket"></a>[/image]

 

[vyv_cox]

Your photos are not visible here but I have looked at one on Photobucket. It looks like the white plastic might be a nylon. I doubt if it is harder than the shaft, if you operate your boat in shallow or muddy water the particles of sand and mud get between the bearing and shaft, causing the wear. Cutless bearings are normally replaced as a single item, brass sleeve lined with rubber. Yours is a little unusual but no doubt someone else will advise where you can get one.

 

[Tranona]

The lining might be Delrin, which is stable in water (unlike most "nylons" which swell). It will be made so that there is clearance around the shaft so that there is a film of water between the bearing and the shaft. Water will either come in through scoops in the bearing housing, or just rely on water pressure. Alternatively there may be a positive water feed from the engine into the tube at the stuffing box end.

As Vyv says the wear is most likely to be from silty water, or if there is a positive water feed, lack of water. It may also be caused by a bent shaft running out of true, although this is more likely to wear the bearing rather than the shaft. Normal cutless bearings have fluted rubber linings to create the water film.

You may have to replace the shaft as there is no point in putting a new bearing on a worn shaft. Suggest you take the shaft and bearing to somebody like Norris www.tnorrismarine.co.uk or Sillette Sonic www.sillette.co.uk for advice.

 

[vyv_cox]

It might be Delrin but it looks rather like nylon to me. I've never seen another like it but all mine have been installed in P-brackets.

 

[nedmin]

If its Nylon I wouldnt put the same back. It will wear your shaft, I would use "rubber" type. I had a childs bike that had a headstock bearing made of nylon and it wore the steel shaft very badly.I know nylon is supposed to be softer than steel etc but in my opinion its useless as a bearing material, especially where silt etc is evident.

 

[vyv_cox]

I'm not quite certain about nylon, but certainly with PTFE, it's the powdered glass that the material is filled with that causes the wear. A colleague did his degree thesis on wear of PTFE against stainless steel and the plastic barely wore at all.

 

[Tranona]

Good to see the piccy. Could still be delrin which can be white, although also black. Looks on the short side to me in relation to the diameter, although difficult to tell from this angle. No water intakes on the housing, so probably has a water feed in the stuffing box.

Suspect the housing will need machining to take a standard cutless.

 

[martinriches]

Thanks for sorting the photo. It is a strange araingment the shaft is 2.3m long and the bearing is about 8 cm with no more support till you get to the engine. I found the coach bolts that fix the engine to the bearers loose so I guess that was the reason for the wear.I am going to install a thrust bearing and Python drive so hopefuly that will sort things out.