O rings - cheapos or not?

MoodySabre

MoodySabre

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Seeing the thread about Aldi O-rings raises a question.

The bottom rudder Delrin-type seal on a Moody has O-rings set in it to keep the wet stuff out. Mine are leaking so I have to drop the rudder to take the seal out and replace the rings. The manual describes these as neoprene O-rings so presumably the type that are £6.99 for 420 are not really the same and shouldn't be used. This is a once every 20 years job and a PITA.

I haven't traced any neoprene ones in small quantities (3 or 4) - should I try a hydraulics equipment company rather than a boatie shop?
 
MoodySabre said:
I haven't traced any neoprene ones in small quantities (3 or 4) - should I try a hydraulics equipment company rather than a boatie shop?
Click to expand...

That is precisely where I get mine, e.g., for the heat exchanger etc. You can get practically any size that you wish, even to fractions of a millimetre in thickness.
 
I use a o-rings in my work, for sealing pressure vessels underwater and we always use nitrile (rubber), because of their performance at low temperatures, high pressures and so on, but unless another material is called for that's what I'd use. I can see a high wear application needing a specialist material, but neoprene doesn't sound too far from nitrile.

They cost about 5p each for a 50mm diameter by 3mm diameter, for example, but you can rarely buy them in quantities less than 1000 or less from companies like Barnwell. Farnell and other on-line companies will sell kits, of the commonly used imperial or metric o-ring sizes. Best to make sure the kit has the size you want before buying it! The problem of getting small quantities is not one I've solved in any other way, than paying more per o-ring.

I also use silicone grease to lubricate the o-rings, e.g. Dow Corning DC4. We used to use Vaseline (i.e petroleum based grease) but apparently it's not good for the o-ring in the long run, it causes them to harden.
 
For the job you have in mind I would want to remove any uncertainty about using an approximate fit.
A decent hydraulic engineer will be able to supply what you are looking for. When I had to have the seals replaces on my US made steering ram the workshop had two "off the shelf" but made up the rest bespoke.
 
Buy lengths of whatever diameter you need and make your own with super glue.
Any good motor factor stocks it (no not Halfords, I said a good motor factor).
 
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