S/T6 crankcase ventilation disc

[Kalle]

Hi
Is there possibly someone who has a ventilation disc according to the photo (photo from Ian Dabney)  to S/T6-1930 or a sketch or photos  how it should look.
There will be some work in the lathe this winter if I'm not lucky enough to find someone at the Forum
Regards
Kalle

[Doug]

Kalle,

Found the breather disk for my S6 project:



The drive dogs have seen better days! The four pockets on the same face are for small coils springs, which I am not sure I have.

-Doug


[fix typo.  23Oct19 -Doug]

[Kalle]

Hi Doug,
So nice to see a photo. If you want to sell this, I would be very happy. Then I have this to be able to manufacture a new one. If you do not want to sell the disc, I wonder how many holes it and the diameter of the holes for the ventilation in the disc. If there is a socket in the camshaft drive for the 4 springs, maybe I can use my camshaft gear.
Visited the Brookland Museum and Goodwood in UK recently and attach photos from the  Douglas motorcycles that were in the latest the Conrod
Regards
Kalle

[Doug]

Kalle,

The ventilation disk belongs to my 1932 Greyhound project, though I likely will machine a new one rather than bother to try and weld up the worn drive dogs. Kingswood aluminum in notoriously cheesy aluminum! (Or aluminium...) I think they were an early pioneer of "Oilite" without realizing it! Even this small disk started as a casting rather than billet rod. I will transfer the screen and steel sleeve over to the new part. That is fairly low on the priority list. However, I will try and create an engineering drawing of the parts by this weekend for you. I need to have another dig through the boxes and tins of parts and see if I have the small coil springs. The bike came fully disassembled, so I am not sure that I have all the pieces. Especially the smaller hardware.

-Doug

[Kalle]

Doug
I sincerely hope you can help me with the measurements and thought to make the steel sleeve with the holes and the screen under the sleeve.
Think it is possible to manufacture the sleeve of a sheet or brass / weld or solder when it is in place in the dics.
Understand that you want to keep the parts that are ok
Kalle

[Doug]

Kalle,

Here is the drawing for the breather disk components:



Full size view as a JPG file HERE

Full size view as a PDF file HERE

Given the wear on the drive tangs, making the disk out of something harder, like bronze, might be an advantage. It does have to be compatible to run against steel.

The design is a curious thing. I have no idea as to the purpose of the 1.688 inch diameter recess since the mesh sits in a recess of the outer ring. The narrow groove presumably is to encourage most of the oil to coalesces of the face and be centrifuged back through the mesh. And why eleven apertures and not something more readily divisible into 360 degrees? Like much of the engine, it strikes me of Freddie Dixon's designs being different, just for the sake of being different!

And a picture of the disk without the mesh/cage and a view of the inside surface of the mesh/cage.





Anyway, hope this helps.

-Doug


[add photos. 25Oct19 -Doug]

[Kalle]

Doug
Oh, oh what a fine job you put in to create a drawing on disc.
Thank you, now many pieces have fallen into place and Iam look forward to procuring materials and manufacturing the ventilation disc.
Such access we have in the club by you and you others who have an incredible experience on our old Douglas motorcycles.
How can I thank you for the help ???
Kalle