The Hamiltonian constraint formalism is used to obtain the first explicit complete analysis of nontrivial viable dynamic modes for the Poincare gauge theory of gravity. Two modes with propagating spin-zero torsion are analyzed. The explicit form of the Hamiltonian is presented. All constraints are obtained and classified. The Lagrange multipliers are derived. It is shown that a massive spin-0(-) mode has normal dynamical propagation but the associated massless 0(-) is pure gauge. The spin-0(+) mode investigated here is also viable in general. Both modes exhibit a simple type of "constraint bifurcation" for certain special field/parameter values.