Forum

[Himself]

Does anyone know the amount of oil the gearbox should hold? I appreciate there is a level plug up to which the gearbox should be filled. The problem I'm having is that the gearbox leaks if it's filled up to the level plug even after fitting sealed bearings and a new oil seal. The gearbox now seems to have dropped to a level where it no longer leaks but I'm worried the level is too low for adequate lubrication. Possibly the solution is to go back to using grease.

[Leon Novello]

Fitting sealed bearings has sealed the gearbox so the air pressure cannot escape like it used to with unsealed bearings. This is most probably the cause of the leaking. A solution which works in similar situations is to drill a small hole in the filler cap up from the inside, but not right through, then drill a horizontal hole from one of the faces to meet it .
Mark the cap when in its tightened position so that the hole is facing in towards the inside of the bike to keep any water out.
There is nothing wrong with gearbox grease, millions of gearboxes use it with no problems.