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I have heard that the sealed bearings were Ok to run that way too, but just never had the guts to try it. Thanks for the information David.I have always run the the drive bearing with both seals in place. Carleton Palmer did also. The bearing company maintained that the lubricant inside the sealed bearing would last for the useful life of the bearing. They made a good case that the bearing would last a lot longer if it were not exposed to dirty oil. On an engine that John Renwick built many years ago he used the sealed bearing as well as the ET236 seal carrier on the case as described in Richardson.
Just as a note, there are at least two different ET236 seal carriers available as I have received both. I prefer the one from Maughan because it is designed so you can leave the bearing circlip in place. I believe the one from the Spares Co. requires the circlip to be removed.
David
On the ex-Cecil Mills bike there is a small banjo bolt in the middle of the chain case filler cap with a length of 1/4" tube extending rearwards to act as a breather. It works well but does not look standard. I remember years ago an article in MPH by someone who did a very complicated outlet from near the top of the dynamo drive extension. From memory this required breaking through into the threaded hole at the rear top of the extension and then making a small hole behind this to allow any pressure to escape. I imagine that this last hole had a fitting to allow a tube to pass to the rear of the bike to let out any excess pressure. With the Walkernators I supply a sealing system to go between the drive bump and the dynamo replacement. So far this does not seem to have caused any problems or, at least, no one has reported any.
Mine looks bad, But if it's Standard !!I'll just throw this on there.... suggest that I believe it came that way from the factory and exit stage left....
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