Hi,
I changed oil in the gearbox recently.
The box gave only 350 cc oil (....) and after that took only another 350 cc oil, no more (...!)
The box was very carefuly rebuild, has the sealed bearing and does not leak.

My feeling is the oil only reaches the gears, but not the part of the gearbox with the kick start and gear change mechanimse. So it won't take the full 600 cc oil.
Strange, because when I look at the technical page, I see a hole in the middle cover of Hans'pictures where the oil should pass. Or not ?
Any ideas ?

Hi Michael...The box should take 1 pint (568cc) according to the worksheets. I have never managed to get the full amount in, generally managing approx. 3/4 pint (426cc)...I normally fill it until the oil appears in the filler neck and then kick the bike over a number of times to 'move the oil around' in the box...Then I can get a bit more in.
Also, on the filler plug it says 'keep full'....If you were to fill the box only until the oil was visible at the lower end of the filler spout this would be quite a bit less oil than if you filled to the highest level possible in the spout (bearing in mind this difference in level is across the whole of the box)...
Finally, you can warm up the oil.....this will make it flow much more easily to all parts of the box....Ian

email (option): ian@wright52.plus.com

Another thought, the gearbox will hold a little more oil with both wheels on the ground, than when on the rear stand.

email (option): jrosson86@att.net

I've had this issue as well, the gearbox only took just over 400cc before overflowing in the spout, hopefully I'll be able to start my bike for the first time on Monday, so the oil will get a good chance to circulate once kicked over a few times. It's on my check list!
Julian

email (option): 79Aust@sky.com

In the 1950's some BSA official operator manuals for bikes with "M" gearboxes state 13fl ozs (370cc), as the post 48 box is not sufficiently different internally from WD box I think its fair to assume the 1pt was recommended incorrectly by BSA, particularly as it can't be easily achieved without messing about & if you do get the extra in, its going to be out pretty quick.

Fact of the matter is 370cc is enough to reach the gears, kickstart quadrant & generally get flung around.