The authors numerically investigate basins of attraction of coexisting peri
odic and chaotic attractors in a gear-rattling impact model. These attracto
rs are strongly dependent on small changes of the initial conditions. Gradu
ally varying a control parameter, the size of these basins of attraction is
modified by global bifurcations of their boundaries. Moreover, the topolog
y of these basins is also modified by appearance or disappearance of coexis
ting attractors. Furthermore, for the considered control parameter range, t
he fractal basin boundaries are so interleaved that trajectories are practi
cally unpredictable in some regions of phase space. The authors also examin
e an example of a crisis on which a chaotic attractor is converted into a c
haotic transient that goes to a periodic attractor. For this crisis, the au
thors show the evolution of transient lifetime dependence of the initial co
nditions as the control parameter is varied.