Method for assembling a hub unit for supporting a wheel shaft

A method of assembling a hub unit, the method comprising:

• providing a shaft member having a first inner raceway on an intermediate portion thereof and a stepped portion that has an outer diameter that is smaller than that of a portion of the shaft member on which the first inner raceway is provided;
• fitting an inner ring, which has a second inner raceway and a small diameter portion formed at one end thereof, around the stepped portion;
• providing an outer ring, which has a first outer raceway and a second outer raceway on an internal peripheral surface thereof, on the shaft member so that the first outer raceway faces the first inner raceway and the second outer raceway faces the second inner raceway;
• interposing a plurality of rolling elements between the first inner raceway and the first outer raceway and between the second inner raceway and the second outer raceway;
• and
• caulking an extended portion of the shaft member, which extends in an axial direction beyond at least the inner ring, in a diametrical outward direction to form a caulked portion, such that the caulked portion presses the inner ring toward an end face of the stepped portion,
• wherein the caulking is performed while radially pressing a large diameter portion of the inner ring, which is located at an axial position of the inner ring, with a pressure piece.