Gearbox oil level question

Curious if anyone knows what the difference in capacity is between in the inner and outer? Reason I ask, I was out last night running in the new premiere carbs, got home and noticed puddle of GB oil... the damn level plug had vibrated out at some point, there was still oil visible in the outer cover though, and took a few ounces to top it off, but got me wondering where the bulk of the volume is as this is a freshly rebuilt tranny (new gears, bushes, bearings)

acadian said:

Curious if anyone knows what the difference in capacity is between in the inner and outer? Reason I ask, I was out last night running in the new premiere carbs, got home and noticed puddle of GB oil... the damn level plug had vibrated out at some point, there was still oil visible in the outer cover though, and took a few ounces to top it off, but got me wondering where the bulk of the volume is as this is a freshly rebuilt tranny (new gears, bushes, bearings)

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According to the service manual for my '73 850 it's .42 liters or just under a pint

I believe there is a hole connecting the inner and outer transmission. Thus, the oil level of both always stays the same. But, when adding
oil, it may take some minutes for the levels to equalize.

lazyeye6 said:

I believe there is a hole connecting the inner and outer transmission. Thus, the oil level of both always stays the same. But, when adding
oil, it may take some minutes for the levels to equalize.

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Guess I should have been more clear, the level plug (I assume) indicates the maximum level but I'm curious what the min level might be?

but I'm curious what the min level might be?

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Absolute minimum and not recommended to try would be with the layshaft gears just still entering the oil, they will then flick it upwards over the rest of the gears and bearings. I would not let it go below 1/2" lower than the max.

Lousy picture due to over-enlarging, but the level screw can be seen at about 8 o'clock from the kick start shaft. This would put the normal running level about even with the bottom of the layshaft.

As noted by kommando, as long as the gears are touching oil, they'll throw it up onto the adjoining gears and bearings while running. With the limited passages between inner and outer, there can't be too much agitation that would throw a whole lot of oil out through the level plug. The fact that oil was being splashed out of the level plug would seem to indicate there was still enough oil to contact the rotating gears.

Nathan