Hi folks,
My take on the front axle "distance pieces".
The Austin stub axles are a bit small/weak for the Healey applications.
Since the distance pieces are considerably larger in diameter than the
stub axles & installed in compression, 50 to 70 ft/lb of preload, they
act to effectively increase the stub axle diameter & greatly reduce the
bending moment on the axles. Stiffen/strengthen the axles, if you will.
A bearing is never intended to have this much side/end load, so the
distance piece assembly is shimmed to reduce the bearing side load while
still maintaining a good deal of compression on the distance pieces to
increase the axle strength.
A very clever if somewhat unknown advantage of this feature.
Dave Russell
BN2
jerry adams wrote:
> 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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