Getting grease to rudder pivots

[bluerm166]

These chunky rudder pintle/gudgeon assemblies fully enclose the 1/2 in bolts where lubrication would be beneficial but I would like to improve things.
From records they seem to have required intervention every ten years or so ,At one time having top hat stainless washers welded into the pintle flanges.This winter the worn bolts ( particularly the top at the neck) were replaced with UNC bolts that have a pretty full shank .
The rudder and stock are hefty and not easily removed when the boat is afloat.So having them disassembled I contemplate drilling vertically down through the hex bolt head
plus sideways to meet this through the shank so that the tube within the gudgeon could be reached by oil if not by grease.The bolts themselves can be tightened solid in the pintle frame so that they do not rotate in it.
Any thoughts on this approach to lubrication please, going so far as to add a greasing nipple on top of the hex ?.
Obviously I can grease before refitting the bolts but this is probably insufficient to last the season/s.

 

[philwebb]

What if you put a grease nipple somewhere near the back of the U-shaped piece? Would the nipple foul the back plate? If not grease could be forced in with a grease gun which would then go upwards and downwards in the pivot. How much grease you could get in would obviously depend on the amount of play between the bolt and the housing.

 

[bluerm166]

An idea but can't be achieved because the bolt passes down through a separate tube/piece of barrel welded in and if the bolts are tight over the flanges of the pintle then the barrel/bolt shank is the real bearing.
However I have had a go at drilling down thro the head of a similar stainless hex bolt on a press this p.m. and it does seem doable with plenty of cutting oil..Its a 3mm hole rather than one large enough to tap a nipple in but I see the possibility of applying one of the new WD40 lubricants (spray grease) directly into that and thence out via horizontal drilling in the shank below .I looked at nipples but see that the smallest requires an 8mm + drilling for tapping in.
Thanks for looking at the issue.

 

[2Tizwoz]

An idea but can't be achieved because the bolt passes down through a separate tube/piece of barrel welded in and if the bolts are tight over the flanges of the pintle then the barrel/bolt shank is the real bearing.
However I have had a go at drilling down thro the head of a similar stainless hex bolt on a press this p.m. and it does seem doable with plenty of cutting oil..Its a 3mm hole rather than one large enough to tap a nipple in but I see the possibility of applying one of the new WD40 lubricants (spray grease) directly into that and thence out via horizontal drilling in the shank below .I looked at nipples but see that the smallest requires an 8mm + drilling for tapping in.
Thanks for looking at the issue.

Replace the washers with oilite bushes.One source.

 

[ducked]

Or possibly nylon washers.

Failing a grease nipple installation (or as well as one) I would probably try driving the greased bolt down through one or more layers of polythene sheet, which will provide solid lubricant which wont wash out as quickly as grease will.

I might grease it, drive it, wrap PTFE　tape around it, grease it again, then drive it down wrapped in polythene. The thickness/number of layers of polythene achievable will depend on the clearance, but even if its tight PTFE　ｗｒａｐ　ａｔ　ｌｅａｓｔ　ｓｈｏｕｌｄ　ｂｅ　ａｃｈｉｅｖａａｂｌｅ

Ｗｏｒｋｓ　ｖｅｒｙ　ｗｅｌｌ　ｏｎ　ｂｒａｋｅ　ｃａｌｉｐｅｒ　ｐｉｎｓ

 

[ducked]

.Its a 3mm hole rather than one large enough to tap a nipple in but I see the possibility of applying one of the new WD40 lubricants (spray grease) directly into that and thence out via horizontal drilling in the shank below .I looked at nipples but see that the smallest requires an 8mm + drilling for tapping in.
Thanks for looking at the issue.

Spray lubricants tend to be rather lightweight for that application, though perhaps better than nothing for a topup.

Perhaps consider a hypodermic syringe for pressure feeding grease. if you can achieve a good push fit to the drilling. These are widely available from Taiwan pharmacies, but UK pharmacies I tried went all shifty when asked, and denied ever having heard of them. (maybe if I looked less like a junkie it would have helped) so I had to order from the Internyet.

I'd think a molybdenum grease (as sold/speccd for CV ｊｏｉｎｔｓ) might be suitable but I dunno about water resistance

 

[bluerm166]

Thank you all.The barrel /tube welded between the flanges of the gudgeon certainly makes things difficult.
I like the idea of in some way wrapping the bolt shank to dampen its movement inside the barrel .But although movement is immediately apparent, being stainless to stainless,you can't get more than a single wrap of thin sellotape over the bolt.
So yes a method of greasing under pressure seems a very good idea.I can't find stainless drive-in nipples in small sizes but I see that there are such for an M5 or M6 thread ( I first looked at 1/8 nipples which required a large BSP tapping) ,and these require only a short thread length.So will aim for an M5 initial drilling through the head emerging horizontally through the shank ,at a point just within the gudgeon and a 6mm tapping for the nipple.
The washers don't actually wear as the major load is sideways onto the barrel rather than downwards but I can fashion large dia delrin washers to fill the small gap under the gudgeon.
If I install the nipple then I will use Morris waterproof grease from a gun.I mentioned WD40 above as they have a new grease product for this kind of purpose which could still be fed via their normal narrow tube.A pressure feed obviously more desirable.
This shows my thinking.

 

[2Tizwoz]

Thank you all.The barrel /tube welded between the flanges of the gudgeon certainly makes things difficult.
I like the idea of in some way wrapping the bolt shank to dampen its movement inside the barrel .But although movement is immediately apparent, being stainless to stainless,you can't get more than a single wrap of thin sellotape over the bolt.
So yes a method of greasing under pressure seems a very good idea.I can't find stainless drive-in nipples in small sizes but I see that there are such for an M5 or M6 thread ( I first looked at 1/8 nipples which required a large BSP tapping) ,and these require only a short thread length.So will aim for an M5 initial drilling through the head emerging horizontally through the shank ,at a point just within the gudgeon and a 6mm tapping for the nipple.
The washers don't actually wear as the major load is sideways onto the barrel rather than downwards but I can fashion large dia delrin washers to fill the small gap under the gudgeon.
If I install the nipple then I will use Morris waterproof grease from a gun.I mentioned WD40 above as they have a new grease product for this kind of purpose which could still be fed via their normal narrow tube.A pressure feed obviously more desirable.
This shows my thinking.
View attachment 204402

The bearings presntly, from your sketch, are the stainless steel top hats and the delrin washers. Oilite washers and bushes last for years requiring little maintenance. If the welded in barrel becomes the bearing it will be expensive and difficult to renew when it wears. Bronze will tolerate seawater.

 

[bluerm166]

Yes,I believe that the original fitting (1987 build) sought to transfer the load from the gudgeons via the barrel to the bolt and thence to the edge of the 4mm flanges of the pintle .The bolts have always rotated in the barrel and the bolts rotated in the pintle.Neither had any original means of being fixed.From records the top hats were in 2009 drilled for and welded to the pintle increasing the bearing surface to 6mm thickness.But yes for stainless this is ultimately insufficient.So the most wear has been on the neck of the bolt on the top fitting -against that edge.As said there is little play between bolts and barrel .
Yes a modern bearing would be the optimum but not easily achieved, For the time being I have replaced the bolts -only UNC proved to have the full 12.7 dia.on the shank -made them long enough so that the plain shank rather than thread fully covers the top hat zone and am adding the means to get grease into the barrel.Had there been a small step to another bolt or rod dia. and the barrel of thicker wall it might have been possible to drill/ream out what is there but that is not the case.
I see what you say about the long life of oilite or similar bearings but you might think that for their time the stainless fittings have served pretty well,if their very chunkiness is now inconvenient.

 

[2Tizwoz]

Yes,I believe that the original fitting (1987 build) sought to transfer the load from the gudgeons via the barrel to the bolt and thence to the edge of the 4mm flanges of the pintle .The bolts have always rotated in the barrel and the bolts rotated in the pintle.Neither had any original means of being fixed.From records the top hats were in 2009 drilled for and welded to the pintle increasing the bearing surface to 6mm thickness.But yes for stainless this is ultimately insufficient.So the most wear has been on the neck of the bolt on the top fitting -against that edge.As said there is little play between bolts and barrel .
Yes a modern bearing would be the optimum but not easily achieved, For the time being I have replaced the bolts -only UNC proved to have the full 12.7 dia.on the shank -made them long enough so that the plain shank rather than thread fully covers the top hat zone and am adding the means to get grease into the barrel.Had there been a small step to another bolt or rod dia. and the barrel of thicker wall it might have been possible to drill/ream out what is there but that is not the case.
I see what you say about the long life of oilite or similar bearings but you might think that for their time the stainless fittings have served pretty well,if their very chunkiness is now inconvenient.

The benefit of oilite bushes are that they come prelubricated and don't require ongoing lubrication.