Gear oil capacity

[Phil C]

My 1965 B40F is supposed, according to the literature, to take 3/4 pint of oil. When I drained it recently, only about 1/2 pint came out. I thought maybe the level had got low due to slight leakage. But when I came to refill it, only about 1/2 pint went in before it was running out of the level tube. Is it because there would be 1/4 pint of dregs in the bottom that doesn't come out of the drain hole? Can't think of any other reason. Unless maybe I should check the level again in case it takes time to run through into the rear outer timing case area.  Phil

[AdrianS]

Fill it up until it drains out of the level tube. Don't add more or you may get leaks.
The oil is splashed around when the gearbox is working so everything gets covered in oil.

[Spaceman]

According to the C15 and B40 owner's manuals I've got, the gearbox oil capacity is 1/2 pint.

[Phil C]

Blimey, you're right, spaceman. Just checked my booklet. Don't know how I got that wrong. (Although I see Haynes (page 11) says 3/4 pint of GTX 20w/50.) Thanks anyway. Mystery solved.
Phil

[JulianS]

This from Pitmans Book of the 250cc BSA might clarify the 1/2 pint 3/4 pint question raised by the Haynes manual.

[Phil C]

Interesting.  But Haynes mentions not just the C15 but also the B40 (see photo.) So it all seems to me a bit vague regarding the B40. I think I'll stick with 1/2 pint of gear oil (Morris Golden Film AG90.)
Phil

[Spaceman]

The B40 owners manuals I have are dated 1965 and 1967 and both specify 1/2 pint for the gearbox. I think the service sheet above is referring to pre-1962 c15's and seems to imply that the level pipe from 1962 onwards gave the correct oil level.

[Phil C]

Thanks very much.