The dynamics of brushless DC motor (BLDCM) is studied in detail from the viscous damping coefficient, a mechanical parameter. While this parameter intervenes in determining the dissipativity of the system; it shows the high complexity of the brushless DC motor. The pitchfork bifurcation is revealed. The Hopf bifurcation is identified twice in the road towards and from chaotic dynamics regions. Rigorous methods such as the center manifold theorem and the normal form theory confirm Hopf bifurcation. The different theoretical scenarios and motor parameters are also illustrated. Real positive parameters of the coefficient are only considered to keep the physical meaning from the analysis. With some special conditions around Hopf bifurcation, the transient chaotic behaviors of the BLDCM are detected. Bifurcation diagrams and Lyapunov exponents are used to support the theoretical findings.