  One loop corrections to the muon decay are studied in a popular and
self-consistent version of the Left-Right symmetric model. It is shown
quantitatively, that the corrections do not split into those that come from the
Standard Model sector and some decoupling terms. For a heavy Spontaneous
Symmetry Breaking (SSB) scale of the order of a least 1 TeV, the contributions
from the top quark have a logarithmic behaviour and there is a strong quadratic
dependence on the heavy Higgs scalar masses. The dependence on the light Higgs
boson mass is small. The heavy neutrinos are shown to play an important role,
although secondary in comparison with the heavy scalar particles as long as the
heavy neutrinos' Majorana Yukawa coupling matrix $h_M$ obeys unitarity bounds.
