Some of Tracy's gear boxes have been flying for over 10 years with
a  totally sealed ball bearing. Sealed rear axle bearings in Chevy's
go  on  for years....

  Paul Lamar

You make a good point there when noting the dependability of sealed-axle
bearings...

But one might argue that the application is not really the same.
Axle-bearings average rotations speed is low (~ 500 rpm) and side-thrust
is typically low.  Front wheel bearings that typically experience
larger/more-frequent thrust are cup/cone, not ball bearings.  Every time
I tear apart the front end of one of my vintage 4x4 pickup trucks

(especially those built before the days of CV axle-joints) I am
amazed that they last at all. The axle-shafts flop around. The seals
quickly get beat-up and barely mange to keep the rocks out.  The
only thing that seemingly allows them to function at all is the fact
that they turn so slowly. And when I lose an axle-bearing on my
truck I have more than 2 minutes to find a nice open spot for an off-
field landing.

R.Berglund

They get a fair amount of side load when cornering. As far as I know
for the last 15 years none of Tracy's gear box's has ever lost a
sealed ball bearing.

Paul Lamar
-

he big qualifier is proper lube in a sealed bearing. I had bought a
Ford wagon that previously had bearing repair kits installed.  These
moved the bearing to an unworn part of the axle.  Sealed on both
sides but with smaller rollers.  Grease went away and the bearing
failed real quick.  We had problems with pilot bearings in the C/S
for heavy trucks a few years ago.  New ones would fail fairly
quickly.  We started popping out the one seal and there was three or
four small dabs of grease the size of pin heads with the coloured
ball.  We put some more in out of the grease gun and put the seal
back in.  You can not pack them or they will just ooze grease out as
it gets hot from internal friction.  Only about 1/2 full is good.
The seals can be removed by getting a pick under the lip and then a
small screw driver.  Use care not to tear the lip unless you want it
open for lube from the housing.


Dale Davies