michaelsalter at gmail.com
Wed Feb 4 18:24:13 MST 2015
Great explanation BUT there is a problem.
Most cars of the last few decades have "push" or "slide" fit bearings on
the stub axles (non driven).
Healeys and most older British cars have spacers and shims to permit the
stub axle nut to be tightened to lock the wheel bearing inners in position
however, most US and other cars still have bearings which are a loose fit
on the stub axle but use nothing to lock the bearings to the axle....How
On Wed, Feb 4, 2015 at 7:44 AM, J Armour <sebring3000 at bigpond.com> wrote:
> 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
> 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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*If you can't fix it with a hammer, you've got an electrical problem.*
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