Cutlass bearing worn out again!

[Neil_Y]

How much does the prop overhang the cutlass? I believe a rule of thumb is something like 3x shaft diameter. If you have more than this it can cause vibration and premature wear. Hope this helps.

More like half shaft diameter to shaft diameter, we aim for 12.00mm as ideal for a soft mounted drive train. This allows for a max of 9.00mm forward movement leaving 3 mm for water to exit the bearing. In practice only a few boats see this much shaft movement.

 

[BlueSkyNick]

You don't say how and where you checked the shaft alignment. Is it possible you have a bent shaft? If you are going to change the bearing draw the shaft and check it for wear and straightness. What are your engine mounts like if they have gone soft you may well have a good alignment measured statically but the engine moving on soft mounts could induce wear.

I agree with these things too. A bend in the shaft cannot easily be seen with the naked eye. Needs a very flat surface with rollers and dial gauge to check properly.

 

[Talulah]

Did the bearing have time to dry out.
I am just fitting a composite bearing and it is loose. The agent assures me it will take up water and expand.
I hope so.
Ken

Having read the subsequent postings about composite bearings is your boat still out of the water? Araldite 2011 is available on eBay ;-)

 

[vyv_cox]

Did the bearing have time to dry out.
I am just fitting a composite bearing and it is loose. The agent assures me it will take up water and expand.
I hope so.
Ken

This is my understanding, despite the contrary claims above. The only phenolic-backed bearing I ever fitted had a noticeable clearance between shaft and bearing before immersion. I was assured that this would be taken up when wet, and it was. This thread says the same.

 

[Talulah]

This is my understanding, despite the contrary claims above. The only phenolic-backed bearing I ever fitted had a noticeable clearance between shaft and bearing before immersion. I was assured that this would be taken up when wet, and it was. This thread says the same.

I might be about to eat humble pie :-(

 

[Bosun Higgs]

Hi All,

Any suggestions are welcome....
I have a Jeanneau S/O 37 (2002) 4OHP Volvo penta, 3 bladed feathering prop.

Last year when I was lifted out my cutlass bearing had play in it. So I replaced it with the Jeanneau "all rubber" type bearings.

I got lifted out yesterday - and I've got exactly the same play (up and down movement) in my cutlass bearing.

When I replaced my last bearing I did checked for alignment and it was found to be spot on!!
Could it be that the 3 bladed feather prop weighs more than the standard prop?

Any suggestions are welcome as to why I have worn another cutlass bearing so quickly.

Many thanks in advance

Ian

I have the same problem and have replaced my bearing twice in three years. All the wear is at the bottom of the bearing as opposed to side to side and I put it down to the silly heavy Radice folder that I have. Mind you the bearing is an odd size because the boat has a grp stern tube appearing out of a shaft log and the id is not big so the thickness of bearing materail isnt great.

I'm thinking of fitting two bearings next time..

 

[Ianqv]

Dear all,

WOW some fantastic advice here!! many many thanks!
I'm still going through the checks but I think I've found the problem!!

You know what they say - check the basics first!!
Well.... I removed my prop today, and then removed my cutlass bearing whilst my prop shaft is still in place!!
It is clear that the prop is NOT aligned as the prop wants to spring down resting on the bottom of the p bracket (well not quite resting as it's sprung in that position)!!
So what I plan to do is adjust the engine mounts so the the shaft is no longer sprung and sits nicely / central in the p bracket.
I'll take some pics so you can see what I mean.

When I replaced the bearing last year I had to remove my shaft prior to getting the cutlass bearing out. So when I checked for alignment I used the feeler gauge method up on the gear box flange. Obviously only a slight out of alignment here is amplified by the time it gets to the end of the shaft.

I will of course be checking engine mounts at the weekend.

H4 - thanks for your email today... I will call in the morning as I now have the P bracket measurements.

Thanks again to everyone who offered advice.

Ian

Cheers

Ian

 

[sailorman]

Dear all,

WOW some fantastic advice here!! many many thanks!
I'm still going through the checks but I think I've found the problem!!

You know what they say - check the basics first!!
Well.... I removed my prop today, and then removed my cutlass bearing whilst my prop shaft is still in place!!
It is clear that the prop is NOT aligned as the prop wants to spring down resting on the bottom of the p bracket (well not quite resting as it's sprung in that position)!!
So what I plan to do is adjust the engine mounts so the the shaft is no longer sprung and sits nicely / central in the p bracket.
I'll take some pics so you can see what I mean.

When I replaced the bearing last year I had to remove my shaft prior to getting the cutlass bearing out. So when I checked for alignment I used the feeler gauge method up on the gear box flange. Obviously only a slight out of alignment here is amplified by the time it gets to the end of the shaft.

I will of course be checking engine mounts at the weekend.

H4 - thanks for your email today... I will call in the morning as I now have the P bracket measurements.

Thanks again to everyone who offered advice.

Ian

Cheers

Ian

disconnect the engine @ the 1/2 coupling
align the shaft in the P bracket & centre of the shaft log wedge in place.
align the engine to the shaft coupling
job done

 

[Ianqv]

disconnect the engine @ the 1/2 coupling
align the shaft in the P bracket & centre of the shaft log wedge in place.
align the engine to the shaft coupling
job done

With help from good old Dad....
I was going to adjust the mounts inside the boat whilst whilst Dad is looking directly at the P bracket giving it some "Bernie the bolt"...... up a bit... down a bit!!!

I'm guessing 1mm of adjustment on the mounts will end up much much more than that at the end of the shaft.

Depends if its raining, the indoor method will defo gets Dad's vote!!

Regards

Ian

 

[sailorman]

With help from good old Dad....
I was going to adjust the mounts inside the boat whilst whilst Dad is looking directly at the P bracket giving it some "Bernie the bolt"...... up a bit... down a bit!!!

I'm guessing 1mm of adjustment on the mounts will end up much much more than that at the end of the shaft.

Depends if its raining, the indoor method will defo gets Dad's vote!!

Regards

Ian

that imho is the wrong way. align the shaft first & then adjust the engine to fit.

 

[vyv_cox]

that imho is the wrong way. align the shaft first & then adjust the engine to fit.

When I replaced my P-bracket I found it far easier to use the method Ianqv proposes than the 'official' one. Instead of measuring thousandths of an inch (or hundredths of a millimetre, if you prefer) at the coupling, you are measuring inches, or centimetres, at the bearing. Provided he allows for the weight of the shaft.

One thing to be aware of whichever way around, is that the shaft must be central in the stern tube. Everything can be in perfect alignment but if the shaft is too close to the tube, or touching it, it will knock when the engine is driving.

 

[Neil_Y]

This is my understanding, despite the contrary claims above. The only phenolic-backed bearing I ever fitted had a noticeable clearance between shaft and bearing before immersion. I was assured that this would be taken up when wet, and it was. This thread says the same.

That's a nitrile rubber bearing in a composite sleeve, not a composite bearing as was mentioned. This still means that there will be bore closure on the shaft, if it's tight in the carrier to start with the bore closure will be greater than if it is a loose fit that waits for water to swell it to a good fit, so I don't quite understand how they can end up with an accurate known clearance on the shaft?

For alignment I believe you have to start from the fixed point which is normally the P bracket bearing, possibly with an intermediate and/or stern tube bearing. The easiest way to check that the carriers are aligned is to have either a new clearance fit bearing or a tube that is a clearance on the shaft and a clearance on the carrier of 0.1-0.2mm, support shaft and see if you can slide the tube/bearing into the carrier and still spin it. Or you could use some fancy laser sight to a target plate where the coupling would be.

 

[vyv_cox]

That's a nitrile rubber bearing in a composite sleeve, not a composite bearing as was mentioned. This still means that there will be bore closure on the shaft, if it's tight in the carrier to start with the bore closure will be greater than if it is a loose fit that waits for water to swell it to a good fit, so I don't quite understand how they can end up with an accurate known clearance on the shaft?.

that's exactly what happened, after swelling the shaft was tight in the bearing. I was never happy with it and never fitted another.