I mentioned this before but no response.  Why not retain the seal
with keepers.  I vaguely recall we went over this a few years ago.
The keeper could be a 360ºcollar or just a couple of tabs.   Jerry

That will work.

BTW the seal is definitely marked National S-1621 350909 and
it is one inch ID and 1.5 inch OD and .310 wide. According to this
Timken/National chart standard seals are marginal in this application
at 7000 RPM. Particularly at 220 F which might be a typical temperature
of the gear box case.

The McMaster part number for the high temp. high FPM shaft speed graphite
impregnated
Teflon seal is 131295K95. Unfortunately it is only 1.25 inch OD which is not
a problem with the new bell housing but will require an adapter
for Tracy's plate.

SKF part number is 9811. Width is is .375" A bit wider. However it is
Nitrile
which is marginal for this app.. Apparently .310 is not a widely available
width. .375 seems to be the standard.

Paul Lamar
-----------------------

I noted that the National 350909 seal (with the embedded metal flange) in
the original mounting plate was still very snugly in place after more 25
hours in the air.  I'd think that the concern about the seal moving out of
the recess would be relieved more easily by putting a coating red RTV on it
before pressing it in.

I'd expect that the temperature is more of an issue in a 20B, or turbo 13B,
application because of the additional friction heating at the higher power
levels.  In these cases the Teflon seal should have the advantage.

I may have further info after replacing my current seal, which I expect I'll
have to do, even though it doesn't appear to be leaking now.

Al

-----------------------------------------

It is difficult to buy none Teflon seals these days. I have searched
and searched and I can't find this National part number on the Internet.
I also have one of these National seals and it looks like Nitriel.

BTW if you want to fly up to Santa Paula I could help you with the pressure
measurements. I have all the materials and two or three manometers
lying around. If not I could drive down next weekend in the
RX8 and bring a bunch of stuff with me.