Oil Leak, Primary Side.

[DaveB500]

Hi Guys.
I have an oil leak on my 1960 A7SS.
The leak is from the primary side, between the Primary case and Gearbox.

My guess its the seal behind the clutch.
In the service book this is listed as  felt washer.

Is that the case?
Or is there an oil seal as well.
I know old bikes do leak, but this is quite bad, only happens when I actually ride the bike, if its left ticking over then that part of the engine is dry.

The only other leak I have is from the rocker cover, and that looks an easy fix. Opps shouldnt have said that.

Dave

[bsa-bill]

HI David
Yes - behind the clutch is a sliding plate and behind it a felt washer.
The sliding plate has an oil thrower on it, these sometimes wear off.
If the plate is at fault fixing will require dismantle/removing the clutch, before going that far best to check oil level in the primary case, you only need enough oil in there for the bottom run of the chain to catch.
The sliding plate is held by two stepped bolts that allow the plate to slide when the primary chain is tensioned.

All the best - Bill

[dpaddock]

The location you describe is also the region where the engine breather exits.

David

[A10Boy]

Dave, the best way to check this is drain the oil from the primary chaincase and replace it with ATF fluid which is great for clutches and is coloured red so you can see which oil is leaking.

Also, if the crank seal is leaking behind the cush, that can pressurise the chaincase and blow oil from behind the clutch.

Andy

[DaveB500]

Thanks guys I will check, out both of these.

The Oil coming out is clean, and doesnt look as if it has been through the engine, but there could be some pressure build up I guess.

Dave

PS now posted a photo of the bike as I recieved it.

[muskrat]

G'day Dave, the other spot there where oil can escape is between the g/box main and counter shaft. If you use g/box type oil you can smell the difference. So if you use ATF in primary you have 3 possibilities, engine oil = breather, red oil = primary, smelly oil = main shaft.
A fellow down in Melbourne makes a sprocket nut with a seal to stop the later.
Cheers.

[cus]

G'day Muskrat,
I'm interested in this sprocket nut, are you able to mention who has them,

regards, Cus

[muskrat]

G'day Cus, John Scerri, Lytedrive, lytedrive@optusnet.com.au I am getting a belt primary from him and he sent me a nut to try. The only prob is that if you use a tri 4 spring adapter it is a mm too thick. No prpobs for std clutch. I let him know and he is sliming it down.
Cheers

[cus]

Thanks Muskrat,
I'll get in touch with him,

Cus

[Johnny J]

Hi!

My name is Johnny and I am new to the forum (and BSA motorcycles. :-))
Recently I bought a A10 Golden Flash 1960 and I also have a problem with an oil leak between the primary and gear box.
It´s quite a severe leak, dripping when standing still and pouring after a ride. I actually checked the primary oil level yesterday for the first time and it was almost empty.

Could someone with more experience than I make an educated guess by the picture if it is the oil seal behind the clutch that needs replacing? In that case, is it spare: 67-3067?
I have marked visible drops located between the primary and chain guard in red:

[bikerbob]

That part No. 67-3067 is the gearbox mainshaft oil seal if you are correct in where the oil is leaking from then I suspect that you may need to replace the felt seal which is behind the clutch along with the sliding plate also you may want to look at reverse scroll that fits on the end of the clutch sleeve the part No for the felt seal is 42-7504 the No for the sliding plate is
66-7520. the reverse scroll No 65-3833 in the parts book it is called a clutch sleeve collar.  You may not need all of the above but to check you will have to remove the outer primary case and remove the clutch completely to check .

[muskrat]

G'day Johnny,  .
I'm leaning towards the g/box seal, if its as bad as that. If it puddles after a good run and is parked on the side stand its g/box seal.  Try the ATF in the primary to see the colour of the oil leak.
Cheers

[RichardL]

Welcome. Looking forward to pictures of the whole bike. What is it that led you to buying an A10? (Really, we already know the answer, but like to hear others confirm the rationale for our obsessions.)

Though it won't be the reason for your leak, while you're in the vicinity, check to be sure there is a spacer (usually four or five washers) between the frame tab and the lower rear ear on the inner primary cover. If none, and it's bolted, the inner cover can get bent or, maybe, fracture.

Richard L.

[Johnny J]

Thank you all for your suggestions, I have a steep learning curve ahead, bought the bike 3 days ago. :-)

I will start with the ATF, if the oil comes from the primary would that mean that the gear box seal might be OK and it¨s the felt washer thats faulty? (Might be a stupid question...)
Can also mention that I might have overfilled the primary after finding it empty, filled it up to the lower screw level on the primary outer cover.
Edit: Forgot one important thing, when it was empty there were no leaks suggesting it is the primary oil that's leaking.

I am used to and spoiled by the relative simplicity of electric motorcycles, more or less 3 parts, motor, controller and batteries, so more or less advanced mechanics requires a different way of thinking. ;-)

Heres a pic of the bike, not completely original as you can see:

[bsa-bill]

Smart bike Johnny J

Don't worry about asking questions daft or otherwise, we've all asked them

You may have over filled the chain case, there is a level plug arrangement on your bike. it can be seen in the photo you posted, to the right of the two red arrows between the silencer and the lower frame tube - black arrow in pic
the large nut screws into the chain case and has a tube attached to it. the top of the tube is the correct oil level, the small stud blocks off the tube.
to fill the chain case - remove the small stud - fill the chain case until oil comes out of the hole - that is then at the correct levl.
If you've over filled it just removed the small stud and let oil out until it stops,
The method you used

filled it up to the lower screw level on the primary outer cover

was the method used before the level plug system was incorporated