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Et48 material

RedRyder

Well Known and Active Forum Website User
VOC Member
Order an ET48 magneto pinion today and most likely you will get one made of Delrin (acetal resin). I have seen them white or "black." Anyway, let's say you have two ET48 lying on the bench and you are deciding which to use - one is the old "fibre" version and one is Delrin. Which will you use and why?

What I'm wanting to know is Delrin preferred because it's better or just because that's what's more easily available?

Next question, has anyone seen problems weighted toward one or the other? I have used both styles and have no worries with either, but curious if I'm missing something.

Cheers,

Bev Bowen
 

chankly bore

Well Known and Active Forum Website User
Non-VOC Member
Just personal opinion,but I'd choose whichever one is lighter.especially if you've got an early magneto with a 15mm. bearing.Both materials are o.k.The only problem was years ago when some bright spark made them out of nylon,which tends to "grow".If you are driving a modern ignition system I don't think it significant which of the materials is used.Make sure Delrin is not hygroscopic.
 
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ClassicBiker

Well Known and Active Forum Website User
VOC Member
The link below will take you to a supplier of metals and plastics that has a physical properties guide for the material that they sell. I've taken some screen shots of the guide pertaining to both nylon and delrin. Neither appear to be particularly hygroscopic. I know that some hard plastic items on my SCUBA gear are made from delrin.
BTW I recommend these folks, they're reasonably priced, ship promptly, and offer a wide range of material.

Steven

http://www.onlinemetals.com/plasticguide.cfm


acetal.jpg nylon.jpg
 

clevtrev

Well Known and Active Forum Website User
VOC Member
Just personal opinion,but I'd choose whichever one is lighter.especially if you've got an early magneto with a 15mm. bearing.Both materials are o.k.The only problem was years ago when some bright spark made them out of nylon,which tends to "grow".If you are driving a modern ignition system I don't think it significant which of the materials is used.Make sure Delrin is not hygroscopic.

The problem with the nylon was heat expansion, nothing to do with water absorption.
Acetal and Delrin are two different animals, one is Homo polymer the other is Homo copolymer. Just make sure there is plenty of backlash.
 

vince998

Well Known and Active Forum Website User
VOC Member
I can vouch for needing backlash.
removed the timing cover last summer to be greeted by a "blob" of oil (my engine doesn´t get chance to produce "blobs")
On closer inspection it was a half tooth from the ignition pinion (francois grosset). Not sure if nylon or Delrin, but it never happened with the old fibre pinions i used to use.
As usual, gave Francois a call and the new one was with me in 3days :eek:
 
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