BMW ATC300 Transfer Case Actuator Worm Gear Repair Kit

This is a machined steel worm shaft for the servo motor on the BMW ATC300 transfer case. The original motor drives the case lever through a worm and gear, and when that drive wears or strips, the motor spins but the transfer case clutch pack never clamps. This shaft lets you repair the motor you already have instead of buying a complete actuator. It is listed against BMW 27107546671 and 27102449712.

Listed fitment: E60 and E61 5 Series xi/xDrive and E90, E91 and E92 3 Series xi/xDrive with the ATC300 case. Check the tag on the transfer case before ordering; X3 and X5 cases use different motors.

A worn servo drive usually shows up as the 4x4, DSC, ABS and brake lights on together, front drive dropping out, or a shudder and jerky torque transfer in tight turns. If the motor runs and you can hear it but the lever does not move, the worm is the usual culprit.

Bench notes: remove the motor from the transfer case, open the housing, and pull the old worm shaft. Compare it side by side with the new one before installing, clean out any plastic debris from the gear housing, and reassemble. Clear the fault codes after the motor is back on the car. The mating plastic gear should also be inspected; if its teeth are gone, replace it at the same time.