Left: line-of-sight velocity of the disc in the central few kpc, (for all the particles) at the start of the simulation before the bar and b/p form for different heights above the plane as indicated in the top left corner (values are in kpc). Right: difference between the absolute value of v_los of the thin and thick disc components, Δv (see Eq. (6)). The thin disc has higher los velocities than the thick disc at the start of the simulation before the bar-b/p forms.