Delrin rudder bearing and marine grease

[Segelplaner]

Hi
We have rebuild our upper rudder bearing and replaced destroyed steel with Delrin.
As you can see in photo a cut was made to inject Marine Grease.



How is marine grease and Delrin together inside upper rudder bearing?

[a64pilot]

I believe Delrin is impervious to grease, but grease can attract and hold dirt and other abrasive particles and they can act as a cutting agent, if they are present.

Delrin is almost never greased in my limited experience. Maybe this will get some conversation started. My take is it’s not necessary, but likely to not be a problem if greased.
If I were to grease it, I would want a zerk fitting so that I could periodically flush out the old grease with new myself

[svHyLyte]

Note that there are several different grades of "Delrin" but all, generally, are chemically resistant to hydrocarbons. Whether the bearing "needs" grease is debatable. However, the grease will tend to protect the rudder stock itself from moisture effects within the bearing, which can be problematic otherwise. While Delrin is resistant to hydrocarbon based lubricants, it might be wise to go with a silicon based grease over the long term, eh?

FWIW...

[Segelplaner]

Ok, we go with marine graded grease. But are aware that the bearing and rudder stock probably needs to be cleaned. The thing is that taking out a rudder is not what you want todo that often.

[a64pilot]

If you have zerk fittings, then you should be able to flush out the old grease say yearly.
Most greases over time will harden into a wax like substance, but if you have enough grease fittings to flush out the old, then it’s just a matter of cleaning up what was flushed out.
Think an outboard motor steering for instance.
I think the type of grease selected also may be important, some greases are soap based for instance, most of course are petroleum based, I’d assume “waterproof” grease to be petroleum based.

I think I would want mine grease-able, but mine is 30 years old, isn’t and I’m pretty sure never been removed, so maybe grease isn’t all that needed?
Pretty sure my bearings are Bronze though.

[mannix2]

For Info on Delrin See: https://www.google.com/url?sa=t&rct=...ddq9je7N-US2pA

[Segelplaner]

Great doc, Thanks

[anchorman]

I have had Delfina bearings on my roller furling head sail for 25 years without ever greasing them. Was told by dealer to never do that, for reasons mentioned before. I flush them out once or twice a year and that is it. Never had a problem.

[Segelplaner]

Ok, Thanks for info

[Compass790]

You don't need grease on Delrin but if you want to use it use silicon grease is my vote.

[thinwater]

No grease, no way. It won't reduce friction measurably. There is no risk of corrosion or galling. It won't reduce wear. In other words, ther eis no upside. But...


Grease will attracting and hold grit. This FAR outweighs any benefit.


Also observe that lubing plastic bearings on deck hardware is never recommended. You can ask them why.


Don't do it.

[Segelplaner]

Ok Thanks

[donradcliffe]

I put zerk fittings in my replacement delrin bearings. Every couple of years during my circumnavigation the rudder got hard to turn when it was highly loaded on a reach and a few pumps with a grease gun solved that problem.

[Cheechako]

Originally Posted by Compass790

You don't need grease on Delrin but if you want to use it use silicon grease is my vote.

I agree!

[GordMay]

Originally Posted by svHyLyte

Note that there are several different grades of "Delrin" but all, generally, are chemically resistant to hydrocarbons. Whether the bearing "needs" grease is debatable. However, the grease will tend to protect the rudder stock itself from moisture effects within the bearing, which can be problematic otherwise. While Delrin is resistant to hydrocarbon based lubricants, it might be wise to go with a silicon based grease over the long term, eh?
FWIW...

Indeed.


Delrin, properly known as Polyoxymethylene or POM, is an acetal homopolymer unless otherwise specified by Dupont.
One huge advantage to POM is its high lubricity. POM is often mistakenly said to have self-lubricating properties. However, it simply has a high abrasion resistance and a very low coefficient of friction, making it appear to be self lubricating. POM can benefit from correctly chosen lubricant. Properly lubricating a load bearing POM part will lengthen its service life. A dry lubricant like Moly or Graphite will work. Also a Teflon based grease such as Super Lube is a good choice. You can also purchase it with exotic fillers like Teflon or Moly, in which case it will be self-lubricating for a much higher price.

➥ http://www2.dupont.com/Plastics/en_U...ign/DELDGe.pdf