C10 primary oil.

[Rick Rybicki]

Come on guys......help! Posted a few weeks ago but no replies...... 1946 C10. How do I stop crankcase oil filling up my primary case. I mean like half a pint in 20/30 miles. Not taken the primary side off yet but it appears that oil seals weren't fitted until some years later. What can I do to solve the problem? HELP!

[chaz]

cant help with the C15 but from previous BSA B40 and A50/65 experience its a common problem. the design has the drive shaft passing through crankcase into the primary case, there was a single brass or phos bronze bush fitted with a groove cut internally that runs opposite running direction that theoretically returns oil. single bush has been replaced by two shorter ones possibly a production reason .

https://www.draganfly.co.uk/images/shop/c15/gearbox.jpg part no 40-3021

https://www.draganfly.co.uk/index.php/component/hikashop/product/7160- says needs two but do not look to be grooved. if so have a word with an engineering shop and see if they can cut one or find a similar and get ground down. maybe if access to a lathe make your own.

there was a quick fix of fitting a felt washer to take up the play and soak oil up. maybe bush worn as steel in brass, grooves worn, I doubt it is seal 40-25 but possible not probable

[Rick Rybicki]

Thanks Chaz, I'm not diving into it until the weather breaks for winter. Enjoying pottering around the lanes. Just take the level plug out of the primary case after a few rides. When I lay it up for the winter I'm going to go through it and see what needs doing to get it as oil tight as possible and to get every ounce of throbbing power out of it!!!!!!

[JulianS]

Worth checking the ball valve situated behind a screw below the timing cover as detailed in the service sheet.

[Rick Rybicki]

Thanks for info re ball valve, I'll check it.
Next business.....Opened the primary case, took off the clutch expecting to find a slider plate and felt washer....no such thing there. Looks as though it was designed to spew oil out!!
No sign of any oil seal, felt washer or anything on crankshaft either. Thankfully no play between crankshaft and crankcase.
Is there a trick to getting the cush drive "nut" off?
How does the splined clutch centre come off? is it on a keyed taper and needs a puller?
In the absence of a slider plate, how is the primary chain tension adjusted?
Where can I find a diagram of this particular chain case. Not featured on Draganfly site.

Had a great day yesterday....went for a 30 mile round trip......rear tire blew out after 6 miles. The inner tube was the newest part of the bike. That's why I started today on all the jobs that need doing. On the good side, I checked the spark plug and I've never had a spark plug so perfectly "Chocolate brown" as recommended in all the manuals. Cheers, Rick.