Radiator cap construction

[David Rainville]

Thanks for the info. It is flexible and the steel disc above it apparently keeps it from bending to far. The next trick is getting it aligned correctly.

[12905]

David:
Is the brass disc flexible? If it is, then it is the sealing surface and buts directly onto the radiator neck. Remember, this system is not pressurised and vapour leakage around the 'seal' is not a problem. The cap is just supposed to keep the coolant from splashing out and foreign objects such as birds, dogs, fingers, etc., from getting in.

[David Rainville]

I'm trying to add the sealing portion of the radiator cap to a new emblem part. A Plymouth cap I picked up some where has what appears to be a brass flange, as the sealing portion and is backed up by a steel flange for support. There is no gasket type material ( rubber, fiber, etc.) to act as a seal, only the brass flange that contacts the radiator opening.
Is this how they're suppose to be constructed? Is there a modern cap I can scavenge the sealing portion from to add to my flying lady?