Push Rod End - PTFE or Nylon?

[Tim Good]

I'm looking at replacing the female 5/8 push rod ends on my whitlock system. Yes I can buy them for £90 a pop from Lewmar. However, it seems that you can get them online from non marine places for a lot less. My question is:

Online it seems you can get both PTFE or nylon lined equivalents. What would be the preference in a marine environment for this application? For example see here:

https://simplybearings.co.uk/shop/B...-Female-Rod-Ends/c3_4544_6221_6224/index.html

 

[DinghyMan]

Nylon absorbs water and swells when wet, PTFE absorbs very little water so probably wont swell to any noticeable amount

 

[Jungle Jim]

Give Igus a call and ask, they are very helpful. I use Igus rod ends in industrial machinery for ice cream factories where they wash down with all sorts of agressive chemicals and have never had a failure.

 

[Tim Good]

Give Igus a call and ask, they are very helpful. I use Igus rod ends in industrial machinery for ice cream factories where they wash down with all sorts of agressive chemicals and have never had a failure.

They seem to do just plastic rod ends. Not sure that's really going to be strong enough to be fair.

 

[pawl]

hi, I'm not sure of the operating conditions these rod ends, but it looks, from the information on the suppliers website that the nylon ones are intended for a lighter duty than the ptfe ones. If I understand it correctly it seems that the ptfe is probably bronze filled, it also has better self lubricating properties that most nylons. In other words you are getting what you pay for. However, saying that something is made of nylon is like saying something is made of metal without specifying what type of metal. There are a number of different types of nylon with very different properties. You have to assume that the people who designed it, specified the best material for the job. Although nylon does take up some moisture post moulding, once it reaches an equilibrium it should be dimensionally stable. Nylon mouldings are normally "conditioned" at the factory, in any case, even if that had not been done, it would take up moisture from the atmosphere after a short while. After all there are thousands of boats using nylon seacocks without a problem. Personally, I would be more concerned about the grade of stainless steel used. If it corrodes, the bearing may seize, I would have thought that 316 grade would be preferable, just my opinion.

 

[andygc]

Given that the original Whitlock and the now Lewmar rod ends have bronze bearing surfaces, doesn't that suggest that they don't think plastic bearing surfaces are the thing to use in steering rod ends?

 

[Tim Good]

Given that the original Whitlock and the now Lewmar rod ends have bronze bearing surfaces, doesn't that suggest that they don't think plastic bearing surfaces are the thing to use in steering rod ends?

Indeed! And I didn't know that!

 

[andygc]

Indeed! And I didn't know that!

I bought mine from defender.com in the US. Even with shipping that was cheaper than paying UK prices - currently listed at $63.99. Listed as "Lewmar Replacement Draglink Rod End Fitting" There was no tax to pay - presumably the total value was below the threshold for HMRC to make a charge. The total bill in Oct 2016 was £132.63.

No doubt I could have spent time searching for something cheaper, but I know that the parts that connect my wheel to the rudder are as specified by the manufacturer.

 

[jdc]

Given that the original Whitlock and the now Lewmar rod ends have bronze bearing surfaces, doesn't that suggest that they don't think plastic bearing surfaces are the thing to use in steering rod ends?

This isn't so - or at least not any more. My boat has Lewmar rod ends (originals 2004, some replacements 2017) and they all have plastic inserts. I think - but this is just look and feel, not any kind of analysis - that the plastic is Delrin. I sailed nearly 40,000 miles before there was so much play that replacement was called for, so I don't think that wear-out is that rapid.