O.K., I guess the long explanation is in order.....
Most precision bearings are designed to be preloaded in order to run quiet
and smooth and to support their loads for a long time. Next time you have a
bearing in your hand, note how relatively loose the rollers are in their
cages. Proper preloading will position the rollers and remove this
looseness without binding the bearing.
The Healey front wire wheel hub is designed to preload the inner and outer
bearings at the same time through the spacer, however the actual amount of
design preload cannot be controlled precisely enough with standard
production tolerances of the bearings, hub, and spacer; therefore precision
shims are used to achieve the preload desired when the hub nut is torqued to
the specified amount (40 - 70 lb-ft).
The workshop manual tells you start with a sufficient thickness of shims to
produce an excessive end-float (free-play in an inboard/outboard direction),
without telling you what end-float is excessive. Note the total thickness
of shims used, then "accurately" measure the end-float with the hub nut
torqued. In the absence of a dial indicator to measure this accurately, I
interpret ANY end-float as too much if it is detectable by hand as I push in
and pull out on the hub. I have found it to be pretty obvious between any
end-float and no end-float, and you can achieve the difference with one
0.003 shim.
Remove shims and check the end-float again. If you have any end-float,
remove more shims. Without a dial indicator, this is trial and error, so
try to zero in on which thickness of shims will eliminate end-float when the
nut is torqued to 40 - 70 lb-ft while allowing the hub to rotate freely.
If one discrete torque value was specified instead of the range given, it is
unlikely that you would find the nut castellations and cotter pin hole in
the stub axle lined up after you eliminate the end-float. Thus, the
relatively wide range of torques specified allows you to continue torquing
the nut to align for the cotter pin. Therefore, it's better to try to
achieve elimination of the end-float at the lower torque value rather than
in the middle or at the high end. I have found that even with everything
correct, I can go from 40 to 70 lb-ft with very little movement of the nut.
In that case, I use another 0.003 shim under the nut to help align the
holes.
As you can see, this process can be "fiddly" to get it right, with lots of
trial and error. Because of frequent removals and reinstallations of the
outer bearing during the process, it's better to do it before the bearing is
lubricated.
I did this job a few months ago when I replaced my front hubs. As I recall,
one side required about 0.032 total thickness of shims, and the other side
was about 0.043.
Steve Byers
HBJ8L/36666
BJ8 Registry
Havelock, NC USA
-----Original Message-----
From: owner-healeys@autox.team.net
[mailto:owner-healeys@autox.team.net]On Behalf Of Alan Seigrist Blue 100
Sent: Sunday, May 21, 2006 8:00 PM
To: B&C Phillips
Cc: healey list
Subject: Re: BJ8 front hub problems
Carroll -
The only purpose of the shims is to align the caslte nut with the hole. You
should only be using 2 or 3 shims at the most ~ a couple thou in thickness
only.
Sounds like to me you have way to many shims on the car.
Alan
'53 BN1 '64 BJ8
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