We expand our previous study on the relationship between changes in the orientation of the angular momentum vector of dark matter haloes ( ‘ ‘ spin flips ’ ’ ) and changes in their mass \citep paperI , to cover the full range of halo masses in a simulation cube of length 100 h ^ { -1 } \mathrm { Mpc } .
Since strong disturbances to a halo ( such as might be indicated by a large change in the spin direction ) are likely also to disturb the galaxy evolving within , spin flips could be a mechanism for galaxy morphological transformation without involving major mergers .
We find that 35 \% of haloes have , at some point in their lifetimes , had a spin flip of at least 45 \degr that does not coincide with a major merger .
Over 75 \% of large spin flips coincide with non-major mergers ; only a quarter coincide with major mergers .
We find a similar picture for changes to the inner-halo spin orientation , although here there is an increased likelihood of a flip occurring .
Changes in halo angular momentum orientation , and other such measures of halo perturbation , are therefore very important quantities to consider , in addition to halo mergers , when modelling the formation and evolution of galaxies and confronting such models with observations .