healeys
[Top] [All Lists]

Re: Re; Front wheel bearings BN2-BJ8

To: jerry adams <cjerryadams@yahoo.com>
Subject: Re: Re; Front wheel bearings BN2-BJ8
From: Dave & M <rusd@velocitus.net>
Date: Mon, 22 May 2006 17:56:12 -0700
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




<Prev in Thread] Current Thread [Next in Thread>