My View !
The same size bearings are installed differently by different car
designers depending on vehicle weight,dynamic forces,speed, braking
power/heat etc.
My six cyl. GMH Holden has the same bearing fitted WITHOUT spacers as
the 3000 has with spacer.
For ease of dismantling and maintenance the bearings are required to be
a sliding fit on the axle.
The risk is; that with load,speed and the accuracy of manufacture of the
axle finished diameter the bearing may very slowly [ creep] rotate or
fast [spin] on the axle. This may result in the inner bearing raceway
[cone] welding itself onto the axle -- not good and has occured on my
Holden,destroying the stub axle.
To prevent the above problem some manufacturers lock the inner raceway
to the axle as Healeys do, use a spacer and shims to enable the nut to
force the outside bearing against the spacer against the inside bearing
hard against the axle shoulder,preventing it from ROTATING.
We ARE NOT pre-loading the bearings, we are end loading the bearings
against the spacer/against the bearing/ against the shoulder. We are
shimming the spacer to ensure there is some clearance in the bearings
proper,that is the raceways to roller surfaces.
This clearance is to allow for bearing expansion with increase in temp.
from speed and brakes which will decrease these clearances. The
nominated end float will have been calculated to result in a
pre-determined bearing clearance approaching zero at max. expected
temperature.
Bearings prefer oil to run in as in industry and gearboxes etc. Oil is
to difficult to keep in front hubs so grease is used. Always use the
thinnest grease recommended with the minimum number of solid additives.
Remember grease is really just a sponge to retain the oil lubricant held
within it.
Pre-loaded bearings are used where extreme loads and/or very positive
location is required [ machine tools] or where high speeds are involved
[ rotation speeds]
These components usually require heavy pressing or heat to remove
bearings from their shafts as in big industrial gearboxes. Such
applications use oil lube and possibly cooling systems to control
temperatures.
Look up any website for the major bearing companies and check there
installation procedures.
Joe
40 yrs. in industry
40 yrs. in Healeys
red one
blue one
|