Master Cylinder Filler Plug

[autolycus]

Still being Minor-less, I can't check this for myself, so would anyone please be kind enough to tell me the essential dimensions of a Minor master cylinder filler plug. In particular, is the thread 1 1/8 inch diameter, 20 tpi? And does the cap incorporate a breather valve assembly under a swaged-in disc?

I'm after one for a non-Moggy that also has a cast iron Lockheed master cylinder, so if the Morris one is correct, I could either order new or cross palms with silver for a non-chewed secondhand one.

Thanks.

Kevin

[Declan_Burns]

Kevin,
I've just measured one. Yes it is 1 1/8" diameter and it is 20tpi.
Here's two pics and you can see the breather holes which vent to a hole on the cast in nut which is blocked off in the second photo.
Regards
Declan[frame][/frame][frame][/frame]

[autolycus]

Thanks very much for going to such trouble, Declan. That's exactly what I wanted to know and see.

Anyone have a spare new or excellent one they'd sell me, please?

Kevin

[katy]

So is that 20 TPI in BSF or UNF thread form?

[Declan_Burns]

There's nothing on the gauge stating UNF or BSF-it's a gauge I bought in the US years ago. 20tpi in UNF would normally be 7/16" or 1/2" acc. my thread tables. BSF would be 3/8"-20.The diameter of the thread on the M/C cap is definitely 1 1/8".
Regards
Declan

[autolycus]

Responding (I hope!) like-for-like to Katy: It looks like 55 degrees from here, but it's the other side of the room, so I can't be completely sure. Perhaps I should go on whether the crest is rounded or flat. Hmmm.

Kevin

[Declan_Burns]

Reviving this thread as it was never really answered:
I'm pretty sure that the master cylinder filler cap has a 1.1/8" X 20 TPI BS cycle thread.
The blanking plug at the rear is 1" X 20 TPI BS cycle thread. This I can confirm as I sent Tracy Tools a blanking plug to check when I bought the die from them earlier in the year.
The dies are available from Tracy tools.
http://www.tracytools.com/taps-and-dies ... YCLE-PITCH
I will add this to the thread sizes topic at the top of the mechanical section.
Regards
Declan