Spring-loaded crown gaskets

[JohnC]

Hi all,

I am working on a couple American watches from the 40s-50s, some of which have crown gaskets that are badly degraded, and mounted on springs between the crown and the case. Can someone advise me on replacing these? I see there are gaskets on Cousins, but these seem to be a) caliber-specific and b) not spring-loaded. Any info and suggestions would be very helpful. Thanks!

[clockboy]

Any chance of a picture John.

[JohnC]

Coming ASAP, thanks. Would also be grateful for a quick rundown on crown gaskets in general - maybe a video or link recommendation. 

[JohnC]

@clockboy sorry for the late reply. On closer inspection the gasket appears to be made of brass. Maybe can keep it, but is it necessary? Wondering if I could at least get a less grungy one. 

[Tudor]

Can you get some measurements on that o-ring? I think you will be OK to use a (esy to get) Rolex crown o-ring. They have a few sizes of crowns and therefore corresponding o-rings. If you measure, and give your preferred supplier a call, they may be able to help.

"off the shelf" standard o-rings (even the odd ones) don't go small enough. I have some of the small "standard" o-rings just in case, but I've not found use for them in a watch yet.

[JohnC]

Thanks, maybe I can get a measurement. One thing I am wondering is, should I just be using generic o-rings on all watches I overhaul? I've only come across a few that have crown gaskets, but it seems like a smart idea to just use them whenever possible. Seems like you're saying that it's hard to find standard o-rings of a suitable size.

[Tudor]

Yeah, really tiny o-rings are non-standard. If you search the Parker O-ring catalogue, you'll find all the "dash numbers" that correspond to ID and cross section. But the smallest standards are:

5-051 which is .070 ID X .040 cross section (thickness of the ring itself) so this is .150 OD (INCHES)

2-001 .029 X .040 (.040 cross section is 1.02mm, so rather "fat"- most are 0.5mm cross section)

2-002 .042 X .050

2-003 .056 X .060

Then the "real" standards start

2-004 .070 X .210 (1.78mm cross section)

and up from there...

If those first sizes will work, you can get bags of 10 or more for less than what one "watch" seal will cost. There are also a few other non standards that are smaller but those are harder to find. Check McMaster-Carr...

[JohnC]

Thanks very much, I'll check them out. Seems like a worthwhile investment!

[Tudor]

Glad to help.