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Singles / Gearbox oil leak
« on: 24 April, 2020, 10:49:27 »
In the current lockdown I decided to revisit my gearbox oil leak. I pulled the clutch etc off and the final drive sprocket, exposing the gearbox. By measurement at both sides of the box I have found that when I fill the gearbox (B & M group plunger 1938-63 on the Draganfly website) to the bottom edge of the filler port, the oil level is:
12 mm above the lip seal where it sits on the drive sprocket
9mm above the splines between the sprocket and the output gear
5mm above the bush between the mainshaft and sleeve gear (items 97 and 98 on the dragonfly parts list/diagram). The bush, item 103 seems a good fit.
I filled the gearbox to the bottom of the filler port then sat and watched. Cold oil, Duckams 20-50, seeped out of the splines at the sprocket and from the bush/shaft interface
Slipping the sprocket into place and nipping the nut up seemed to sort the splines seepage. I expect it might seep thin hot oil, but hopefully not to any great messy extent ( or am I wrong?)
Currently I'm thinking my biggest leak is from the bush area, which is predictable as there has to be some clearance there and hot oil will find it. My question (eventually) is whether the felt and cork sealing rings which sit in that area when the bike is assembled actually prevent leakage, or is the leak inevitable? It seems a pretty crude seal system given that it sits flooded when the gearbox is properly filled. Am I missing a trick somewhere? I can run the bike with 10 mm less oil in the gearbox as I only do short cafe runs at present, but I would like to achieve better than that.
Any advice welcome as this is a major pain as I don't like to park up and drip oil around the place.
Thanks.
12 mm above the lip seal where it sits on the drive sprocket
9mm above the splines between the sprocket and the output gear
5mm above the bush between the mainshaft and sleeve gear (items 97 and 98 on the dragonfly parts list/diagram). The bush, item 103 seems a good fit.
I filled the gearbox to the bottom of the filler port then sat and watched. Cold oil, Duckams 20-50, seeped out of the splines at the sprocket and from the bush/shaft interface
Slipping the sprocket into place and nipping the nut up seemed to sort the splines seepage. I expect it might seep thin hot oil, but hopefully not to any great messy extent ( or am I wrong?)
Currently I'm thinking my biggest leak is from the bush area, which is predictable as there has to be some clearance there and hot oil will find it. My question (eventually) is whether the felt and cork sealing rings which sit in that area when the bike is assembled actually prevent leakage, or is the leak inevitable? It seems a pretty crude seal system given that it sits flooded when the gearbox is properly filled. Am I missing a trick somewhere? I can run the bike with 10 mm less oil in the gearbox as I only do short cafe runs at present, but I would like to achieve better than that.
Any advice welcome as this is a major pain as I don't like to park up and drip oil around the place.
Thanks.