A differential mechanism includes annular wave springs, each spring located between the back of a side gear and the inner surface of a differential casing. The spring is formed with waves that extend around the spring's circumference and radially across its width, each wave having an amplitude formed of angularly spaced peaks and valleys spaced angularly and located between the peaks. When the mechanism transmits torque, each spring is compressed by a thrust force at the mating teeth of the pinion and side gears, thereby producing a spring force that urges the side gears toward the pinions.