1
general::
Break loose from restraint, misbehave. For example, There's always one child who'll kick over the traces as soon as the bell rings. This metaphoric expression alludes to the straps attaching a horse to a vehicle, which the animal sometimes gets a leg over in order to kick more freely and thereby refuse to move forward. [Mid-1800s]
American Heritage Idioms
2
general::
Phrase(s): kick over the traces
Fig. to do what one is meant not to do; to rebel against authority. (Alludes to a horse that steps on the wrong side of the straps that link it to whatever it is pulling.) • At the age of sixty, Walter kicked over the traces and ran away to Brazil. • All these young kids seem to want to kick over the traces.
McGrawhill's American Idioms And Phrasal Verbs