Hi Rowland
"is there any particular type of grease that should be used, or
> any that should definetely be avoided, for the Tufnol-aluminium
> interface?"
My accelerated cockpit module came assembled with a black grease. All was
free when we picked it up. Then when it was about ready to install, it had
a slight binding, not much. Then when ready to install it was questionable
binding, so we bit the bullet and beat the aft bushing out and lapped the
front one with a lap purchased from McMaster Carr. It begins as a lap,
then turns to polish, then disappears. What a pain! Amazing how free the
controls are now! You use pig oil with lap and it makes a mess and took
days and days to complete. If you use a lap that does not disintegrate, it
can embed itself in tufnal and wear on aluminium forever.
Anyway that black grease expanded the Tufnal. I for one would not put any
grease on Tufnal unless you know for sure that the selected grease over
years and years will not expand Tufnal. Not only did the Tufnal expand and
make a smaller ID, it got thicker and was binding in thrust as well!
I have some spray for lubricating aluminium (sliding windows with teflon),
it flashes off quick and leaves some teflon, if you forced me to make a
choice what to lube with, that would be my choice. I took some Tufnal that
I sanded glaze off all sides and measured dimensions with a precision
micrometer, kept spraying for a few months with the aluminium teflon spray
and dimensions were stable.
If cockpit module were installed and bushings expanded, you could probably
lap a better fit in place as I described after a bit of surgery and
repair. You would however make a mess beyond belief!
I saw somewhere someone bonded into the bushings a plastic tube to connect
to an aerosol can.
BE CAREFUL WITH GREASING!
Mine may get a quick spray of the teflon aluminium spray once every few
years.
Ron Parigoris
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