Midget front wheel bearings

Midget front wheel bearings are of the angular contact type.  They are non-adjustable and are assembled with a solid spacer between the inner and outer bearings so that both are locked on to the stub axle as a solid unit when torqued up to 45 lb-ft as specified.  Once so assembled the bearings have no play and no preload.

To achieve this, the bearings were made to a high degree of precision and “face adjusted” so the inner and outer of each race are consistently aligned.  Regrettably, replacement bearings available today are not made with this degree of precision, and it is not unusual to find a small amount of play or pre-load once installed.

Ideally, bearings to the original tolerances and precision would be fitted, however, these are getting increasingly difficult to find.  As an alternative, this situation can be remedied as follows:

  • If pre-load, shims can be inserted between the spacer and outer bearing, similar to the original installation on an MGB.  There are no off-the-shelf shims that I am aware of, but MGB wheel bearing shims ATB4240, ATB4241, ATB4242 (3,5,10 thou resp) are close enough in size to use.
  • If play, machine a small amount off the spacer between the two bearings.

Generally, .003″ is sufficient to remedy the situation for either play or pre-load, and I have yet had to go beyond .005″.   If machining the spacer to elinate play, I recommend doing so by .003″ at a time, doing a trial assembly in between each session checking for absence of both endfloat and drag.   Obviously great care must be taken to ensure that the inner and outer faces of the spacer remain parallel to each other.

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