B40 Primary Chain and Gearbox oil checks.

[grahamkeen1]

Hi,
I have a 1966 B40 and want to check and top up the oils in both the gearbox and primary chain case.
I bought a Haynes "BSA Units Singles" manual and am incredibly disappointed with it; all their car manuals I've used have always been brilliant but not this bike one.
I thought the gearbox would be easy as it appears to have a filler plug and a dipstick as per the first photo, but both are just caps for casing holes so I can't see how you check the level. The second photo shows the casing which appears just to have a screw in the center of the casing which I assume is just that, a casing screw not a level hole.
On the primary chain side, there is a central plug which has the clutch adjuster behind it. If this is also the primary oil level, then I can't see if there is a separate oil feed hole or you just use the same hole, photo three.
Thanks in advance for any help which will be very much appreciated.
Regards, Graham.

[JulianS]

On the chaincase the lower front fixing screw is the level and the next back is the drain screw.

On the gearbox beneath you will find a hex head with a smaller hex screw in the middle. Remove as one unit and that drains the box, you will find a standpipe on the larger. With smaller hex removed and larger replaced add oil until it runs from hole, then replace the smaller.

You can access an instruction manual for the 1965 C15/B40 in the members area of the BSAOC website. This will help with your 1966 model.

[grahamkeen1]

Thank you Julian, very much appreciated, I will have a good look tomorrow.

Can you please point me to how to access the instruction manual ? I am a member but can't find that section.

Regards,
Graham.

[JulianS]

Click on the members area box - insert you surname and membership number - library tag on blue line - library search - then search on range and model - the 1965 book comes up under the C15, the book deals with both C15 and B40.

There is a lot of unit singles on this link;

https://www.bsaunitsingles.com/Archive_home.htm

[grahamkeen1]

Once again, thank you Julian.

There appear to be so many variants of drain / level plugs in the various documents I looked at from the last link you sent. One even has the exact opposite of the primary chain case level and drain access points from your description !

On my first photo, the top of the crankcase has two 'access points'; I assume the one with the screwdriver slot is for filling, but what is the other for, it appears to go into the gearbox as well ?

Lastly, most documentation says use 90EP in the gearbox, which is what I'd expect, however the Haynes manual says GTX 20/50 for C15 & B40, surely that is incorrect ?

REgards, Graham.

[JulianS]

The slotted plug at the top of the case is a sealing plug. On the pre B40F side points engines the distributor fitted there. The oil pump drive is found further down beneath it. It only gives access to the engine not the gearbox.

The hex is for filling the gearbox.

There is some suggestion that the additives in EP gear oil can have a adverse effect on phosphor bronze gearbox bushes.

I use a non EP gearoil in my A10 gearbox, better safe than sorry in my opinion. Others may have a different view.

https://www.morrislubricantsonline.co.uk/golden-film-ag-90-gear-oil.html

[grahamkeen1]

Julian,
Thank you once again.
I will get some non-EP oil as you suggest.
Regards,
Graham.