Stairmaster Steppers 4400CL Drive Shaft Assembly

Apr 28, 2023

1. Remove the bottom cover.

2. Remove the step chain retainers.

3. Support the pedal arm. Unhook the pedal arm return spring from the spring hanger. Lift the step chain up and off the clutch sprocket and lower the pedal arm to the floor. Repeat on the other side.

4. Remove the snap ring from the left end of the drive shaft.

5. Remove the drive chain.

6. Remove the sprocket and the other small parts from the left side of the hub assembly.

7. Slide the drive shaft to the right, out of the hub assembly. If you remove the right-hand clutch sprocket from the drive shaft, do not confuse it with the left-hand clutch sprocket.

8. Loosen and remove the two remaining bolts and nuts that hold the hub assembly to the frame. Remove the hub assembly.

9. Inspect the drive shaft, the bushings, the thrust washers, and clutch sprockets for excessive wear or pitting. Replace worn-out components.

10. To reinstall the hub assembly, carefully reverse the disassembly procedures. Be sure that the right and left hand clutch sprockets are positioned correctly; the wide shoulder of the sprocket should be facing away from the hub on both sides.

11. Chain Tension. The drive shaft is mounted in an eccentric hub, Rotate the hub so the marked hole is in the 12 o'clock position, lining up four holes in the hub with the four holes in the frame. Use the hub position when reinstalling the drive chain since the distance between the drive and transmission shafts is at a minimum. The hub is in the proper position when the drive chain has a total of 1 to 1-1/2" (2.5 to 4.0 cm) of play at the slackest point. As the drive chain stretches with use, increase the chain tension( and the distance between the two shafts) by rotating the hub counterclockwise. The distance between the two shafts is greatest when the marked hole in the hub is at the 8 o'clock position.

12. Reinstall the covers.