List,
Just to add to what Steve said. Donald and Geoff were good well grounded
engineers with lots of practial and racing R & D. The BN1 had ball bearing
type front wheel bearings and probably had stub axel or bearing failures which
cause them to go the Timken tapered roller bearing for the front. Since the
front wheels and axels receive a lot of both radial and axial loads I can
understand why the Timken tapered roller bering was selected. For these
bearings to preform as designed the must have preload so that the races are not
damaged from shock loads during driving. The ideal preload would be exactly 0
lbs, so that the bearing would not move during any axial load since the cars
weight has already loaded the radial load. (Actually the Timken design has
both radial and axial loading built in when the bearing is install and weight
is put on the bearing, with 0 lbs. preload).
The distance piece and the shims were added to give the bearings as colse to
0 lbs of preload as possible. In actual practice you can't get 0 lbs unless
you are very lucky, so the next best thing is to try for a few ozs. of preload.
A few ozs. of positive preload is better than a slightly negative preload,
since the negitive preload will give you some slack and cause some small load
shock during axial loading. Too much preload will cause brinelling and
premature bearing failure.
When installing the bearings and setting up preload, set up with light oil on
the bearings and without the grease seal, some say set up the bearings dry.
After preload is set then grease bearings and install grease seal. This is a
lot of work but should be done right.
Jerry
BN2
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