Author Topic: Gearbox oil seal  (Read 356 times)

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Gearbox oil seal
« on: 17 May, 2018, 19:55:13 »
Had a search and this has been discussed before - but I can't find a solution.
I replaced a  leaky oil seal on the output shaft of  my '54 plunger B31. The leak persists! The seal is fitted nicely, square to bore and just below flush with gearbox case. Sprocket shoulder the seal contacts is in good condition and I have a felt and cork seal on the output shaft - which I think is intended to seal off the end of the shaft splines. I've looked at this again and again and can't work out why the leak is there and so  bad.

A few factors - I filled the gearbox to the level of the screw in inspection port on the right hand side of the gearbox as advised - this fills box to just about the level of the oil seal on the left side. Should I try less oil?
                      Ive read about putting grease into  gearboxes - possibly reduce leakage, but not something I've done before.
                      The oil seal is meant for a shaft diameter of 1.625 " (according to the size marked on the seal - which I believe refers to the associated shaft diameter not the seal size.) but the shoulder on the sprocket is 1.722" - not a lot different, but the old seal looks a bit stretched when I try it on the sprocket -         has anyone a sprocket they can measure for  comparison (I may be over thinking this!). Puts the shoulder on my sprocket at  between 1 5/8" and 1 3/4" which seems a strange choice for an old  british bike.
I can just let it leak but would rather not. Any advice welcome.