If a differential only makes noise during turns, what is the likely cause?

When a differential only makes noise during turns, it typically indicates an issue with the components that are under increased strain and movement when the vehicle is cornering. Worn differential pinion gears are often the primary suspect in this scenario because these gears must rotate and manage the torque differences between wheels as they turn. When the vehicle traverses a curve, the outside wheel travels a larger distance than the inside wheel, leading to the need for the differential to allow for this speed variance.

If the pinion gears are worn, they may not mesh smoothly during these turns, resulting in noise. This noise could be attributed to the gear teeth not engaging correctly or having worn edges, which causes them to rattle or grind against each other under the load of turning.

The other components listed, such as drive pinion bearings, carrier bearings, and axle bearings, while they can cause noise, are generally not isolated to only occurring during turns. Instead, wear in those areas can lead to continuous noise regardless of the vehicle's direction, as they impact the constants of rotation rather than the variable nature of a differential's action in turns.