Time evolution of the intercentre separation of Sb + Sb mergers of equal-mass galaxies with internal spin parameter λ = 0.04 colliding along elliptical orbits. Different panels show different choices for Δ(t): panel a) the intercentre distance, panel b) the specific orbital angular momentum, panel c) a weighted non-canonical distance in phase space based on the Euclidean notion of distance, and panel d) the product of the intercentre distance and relative velocity. Normalisation units R_p and V_p refer to the virial radius and velocity of the primary halo, respectively. Galaxy centres are calculated from the 10% fraction of the most closely bound luminous particles. Coloured solid curves in each panel show the merger histories corresponding to the 12 initial orientations adopted for the internal spin of the haloes (see legend in panel a and Table 2). In panel a, the intersection of the curves with the black horizontal dotted line marks the onset of the mergers. In panel b, the black horizontal dotted line marks the value of j₀₅ inferred for the black solid curve (X90Y90). The values of j₀₅ for the other curves are very similar.