What can cause a 4WD transfer case to jump out of gear?

A 4WD transfer case may jump out of gear due to dry front and rear driveshaft slip yokes, which can inhibit the smooth operation of the drivetrain. When these yokes are dry and lack proper lubrication, it can result in binding or excessive play in the drivetrain components. This can prevent the transfer case from remaining properly engaged in the selected gear, leading to the transfer case jumping out of gear under load or when the vehicle is in motion.

Dry slip yokes can cause friction or inadequate engagement, making it difficult for the transfer case to maintain its gear selection. Regular maintenance, including lubrication of the slip yokes, is crucial for the reliable operation of the 4WD system.

While different size tires can create a range of issues including drivetrain binding due to mismatched tire rotations, in the context of this particular question, it is the condition of the slip yokes that specifically indicates an issue leading to the transfer case disengaging.