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Joe,
Thanks for the very clear explanation!
Gary Hodson
-----Original Message-----
From: J Armour <sebring3000@bigpond.com>
To: healeys <healeys@autox.team.net>
Sent: Wed, Feb 4, 2015 8:12 am
Subject: [Healeys] Bearings
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.
Joe
_______________________________________________
Archive: http://www.team.net/archive
Healeys@autox.team.net
http://autox.team.net/mailman/listinfo/healeys
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<font color='black' size='2' face='arial'>
<div><font style="background-color: transparent;">Joe,</font></div>
<div>Thanks for the very clear explanation! </div>
<div>Gary Hodson</div>
<div> </div>
<div> </div>
<div style="color: black; font-family: arial,helvetica; font-size:
10pt;">-----Original Message-----<br>
From: J Armour <sebring3000@bigpond.com><br>
To: healeys <healeys@autox.team.net><br>
Sent: Wed, Feb 4, 2015 8:12 am<br>
Subject: [Healeys] Bearings<br>
<br>
<div id="AOLMsgPart_1.2_e8bf1cd7-3883-43a0-bb37-49ad058578ab">
<div class="aolReplacedBody" style="color: rgb(0, 0, 0); font-family: Calibri,
sans-serif; font-size: 14px; -ms-word-wrap: break-word; -webkit-nbsp-mode:
space; -webkit-line-break: after-white-space;">
<div>
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.
</div>
<div>
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'
</div>
<div>
<br>
</div>
<div>
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.
</div>
<div>
<br>
</div>
<div>
I have seen Healey size front wheel bearings fitted to an Australian G.M<font
face="Arial, Helvetica, sans-serif" size="2">.</font> 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
</div>
<div>
<br>
</div>
<div>
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.
</div>
<div>
<br>
</div>
<div>
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.
</div>
<div>
Alternative is a huge hammer, a big press or lots of heat and usually throw it
away.
</div>
<div>
<br>
</div>
<div>
Joe
</div>
</div>
</div>
<div id="AOLMsgPart_2_68d504a3-62d6-41ed-a5a7-5b62e7493afa" style="margin: 0px;
color: rgb(0, 0, 0); font-family: Tahoma, Verdana, Arial, Sans-Serif;
font-size: 12px; background-color: rgb(255, 255, 255);">
<pre style="font-size: 9pt;"><tt>_______________________________________________
Archive: <a href="http://www.team.net/archive";
target="_blank">http://www.team.net/archive</a>
Forums: <a href="http://www.team.net/forums";
target="_blank">http://www.team.net/forums</a>
<a href="mailto:Healeys@autox.team.net";>Healeys@autox.team.net</a>
<a href="http://autox.team.net/mailman/listinfo/healeys";
target="_blank">http://autox.team.net/mailman/listinfo/healeys</a>
</tt></pre>
</div>
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_______________________________________________
Archive: http://www.team.net/archive
Healeys@autox.team.net
http://autox.team.net/mailman/listinfo/healeys
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