The effect of the potential well size on the spectra and B(E2) transition rates of the Z(5) solution of the Bohr Hamiltonian, corresponding to triaxial shapes, has been studied. Convergence to the Z(5) solution is obtained for large well sizes. The results are compared to the infinite well, the harmonic oscillator and the rigid triaxial rotor results. The relevance of this solution to the prolate to oblate shape/phase transition in neutron-rich nuclei in the W-Os-Pt region is discussed.