The aim of this article is to investigate how the so-called transmission er
ror in a gear develops in a wear process. A finite-element procedure for ca
lculating wear between two elastic bodies in contact is developed that incl
udes constitutive laws, representing the behavior of the interacting surfac
es. When treating a gear problem, large rotations must be included. This is
done by analyzing a sequence of finite-element models along with an interp
olation procedure. The constitutive laws of interacting surfaces are Signor
ini's contact law, Coulomb's law of friction, and Archard's law of wear. By
formulating both Signorini's contact law and Coulomb's law of friction by
means of projection equations, the complete formulation of a time increment
of a quasistatic wear-friction evolution problem becomes a system of nonsm
ooth equations. Then, a modified Newton method is applied to solve this sys
tem. The transmission error can be found from the infinitesimal displacemen
t field superposed on the rigid body configuration. Results from the simula
tions show that wear will increase the peak-to-peak value of the transmissi
on error. This is most significant in a gear when some kind of modification
of the gear flank is applied to minimize the transmission error in an init
ial state.