[Healeys] Front wheel bearings

[P.J.Aeckerlin]

Gary,
Unfortunately I left all my technical handbooks behind when I quit 
working, but I remember very well a paragraph in the Timken Bearing 
Handbook where it was described in detail how one had to install a set 
of Timken (= taper roller) bearings. The equipment I sold at that time 
(valve actuators) were depending on the proper functioning of the main 
Timken bearings and I spent a lot of time adjusting bearing play with shims.

A taper roller bearing (like our front wheel bearings) has to be fitted 
with a light preload in order to ensure a long bearing life. 
Theoretically no preload  and no axial play would be ideal, but as that 
is very difficult (and time consuming!) to obtain a light preload is 
preferred.

When you look at the complete construction of a Healey front wheel  you 
will notice it is an assembly of various items which, when built 
together, have to form a rigid bearing construction. All these items are 
manufactured separately and therefore all these items have their own 
machining tolerances. It means that, when you put the various bits 
together, you can be sure that the final distance between the outer 
bearing rings and the inner bearing rings is not what it should be 
according to the theory. It is for that reason only that shims are used. 
They are needed to compensate for the manufacturing differences of the 
various components which together form the front wheel bearing assembly.
This means that, if you just take the bearings and shims out, clean them 
properly and then put them back again, you can use the shims you found 
during dismantling (provided the guy who did this previously knew what 
he did!). It also means, however, that when you decide to renew the 
bearings or any other item of the construction you  have to follow the 
lines set out in the manual and (maybe) use other shims to get the best 
bearing assembly - because every bearing and every component has his own 
manufacturing tolerance and -limits.

In my opinion the discussion about strengthening the axle stub by pre 
stressing is a no-go issue. Tapered roller bearings ALWAYS need some 
kind of adjustment possibility. BMC did that with shims, nowadays 
machining tolerances are much better than in the past and therefore the 
use of shims has reduced in modern constructions.
Jack Aeckerlin, The Netherlands
1964 BJ8 29432

Warthodson at aol.com wrote:

>I am going to be rebuilding my front suspension in a few weeks so I have been 
>following this topic with particular interest. I am inclined to reinstall the 
>shims & spacer, but I would really like to know what purpose they serve. I am 
>not convinced by the "increased pillar" theory. If the original purpose was 
>to make the stub axle stronger there sure would have been better (cheeper, less 
>labor, stronger) ways of accomplishing this. By the way, not all British cars 
>use spacers. Triumphs don't.  
>Gary Hodson