[Healeys] Bearings

J Armour sebring3000 at bigpond.com
Wed Feb 4 05:44:34 MST 2015

When bearings are fitted into an assembly that is somewhat mass produced and
expected to be dismantled easily either the inner or outer race is required
to be a sliding/ loose fit by using  predetermined clearances. Bearings can
be loose/clearance/sliding fit or size for size or interference fitted. In
the case of our Healey front wheels the inner race fitted to the axle is a
sliding ( loose) fit so that it can be easily dismantled. With the rear
wheels the inner bearing race  is a sliding fit on both the axle housing and
the outer race in the hub therefore both need to be prevented from turning
which can occur with the cyclic load and deflection of the inner and outer
races because both are clearance fits.
The inner race is locked to the axle housing by torqueing the big nut. The
outer race is prevented from turning by the fitting of the spacer to provide
the necessary protrudance to allow the rotating axle to clamp it and prevent
the outer race from what is known in the industry as 'bearing creep'

The more heavily loaded ( dynamically ) the bearing is and depending on the
manufacturers clearance allowed to provide ease of assembly and disassembly
the more likely the bearing is to creep or rotate on its shaft or within its
housing. Remenber that the load on a bearing is basically vertically down so
as a hub or axle rotates the bearing race will flex / deflect.  This allows
it to creep and in extreme cases to spin and damage the surface it sits in
or on.

I have seen Healey size front wheel bearings fitted to an Australian G.M
vehicle without the famous Healey spacer and shims spin the inner race of
the bearing and weld itself to the shaft. This resulted in the scrapping of
the whole stub axle

Remember the manuals are to tell us what to do not necessarily why to do it.
Most manufacturers do base their designs on some experience which we may
never be exposed to. The manual also allows for owners with somewhat less
knowledge to maintain their car and therefore they will maybe over
compensate for the inexperienced mechanic.

Note, with bearings and other machine bits a shaft and hole that are
required to be assembled and disassembled with simple tools will not go
together when they are the same size. That is why tolerences are specified
and a clearance in thousands of an inch are specified.
Alternative is a huge hammer, a big press or lots of heat and usually throw
it away.


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