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Subject: Re: Front Bearing setup
>Duncan if
>the expansion you got to the tufnol would have occurred with a graphite
>lubricant
I wouldn`t know. Unless the graphite is in an oil/grease carrier.
>small hole in the top of the tufnol bearings to
>allow the insertion of a tubular applicator to inject atomised grease with
>a medium that later evaporates leaving the grease in place.
The solvent carriers in many spray lubs. REALLY make the Tufnol swell. But
it does seem to go back down with time as the solvent slowly disappears.
> Is the general
>consensus that the friction comes from the tufnol swelling throughout its
>thickness which effects the rear face of the CS03 bush against it, or is it
>the shrinking nature of the hole in the bearing constricting on the CS03
>bush?>
The swelling takes place mostly perpendicular to the direction of the fabric
in the Tufnol. There was plenty of radial play left in mine. Although
conical misalignment of either bearing can cause friction in addition.
Tightening of the four bolts on the front bearing seems to pull it well out
of line, even when its been set up square on a (by now) well cured flox pad.
I liked Fred Fillinger`s idea of using fishing line to maintain
axial/conical AND radial alignment and would certainly try this on the back
bearing.
Even when all this is done, accurate set up in the inner module is still
just as critical.
Nevertheless, I really think its worthwhile on any aircraft to spend alot of
time in getting the controls friction-free and free from slop; it makes for
far sweeter handling, especially on a first flight when control friction can
mask out-of -trim asymmetries.
Duncan McFadyean
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