How to repair an AutoHelm
ST4000+ Z326 Wheel Autopilot
will not disengage and allow easy wheel steering
when Drive Lever is released .
Problem- Roll Pins in Drive eccentric assembly are broken.
Parts- not available from Raymarine
. Must purchase
new Mk II
Solution- Remove broken Roll Pins in eccentric assembly and Drive lever and replace with copper wire- 14 or 12 gauge
1- DO NOT proceed until you have the service
REFER TO PAGE 16 of 34 for illustration.
***All part numbers referred to below are from the service
2- Remove (unscrew) Autohelm
from Wheel assembly- parts
2a- Apply marks to wheel and autopilot wheel for correct orientation when reassembling the unit.
3- Remove Wheel autopilot from wheel- hex screws are metric.
4- Use a screw drive to separate the two halves of the black wheel autopilot- parts
4a- Remove 5 screws (part 3) from the Support plate (part 4).
5- Verify that the Roll Pins in the Drive eccentric assembly (part 11) have failed as evidenced by the free spinning of the eccentric assembly (part 11) and Drive Wheel assembly (part 10) around it.
6- Drive out Roll Pin (part 8) in Drive lever (part 9) using a nail or suitable drift pin. Make certain you don't use something oversized to drive it out as the Drive lever handle (part 9) may crack.
7- Carefully remove Drive lever (part 9) from Drive eccentric assembly (part 11). It will take some effort. The lever is plastic- IT WILL BREAK IF YOU FORCE IT.
8- Drive the Drive eccentric assembly (part 11) shaft out of the Drive eccentric assembly (part 11).
9- Remove any remaining pieces of the roll pins that were in the Drive eccentric assembly (part 11).
Comment- for the following steps I used a piece of 12 guage copper wire (single strand). There isn't much torque applied to the Drive eccentric assembly when engaging the autopilot so you could use even 14 guage wire.
Comment- if you don't want to drive out the holes- use Super-glue to glue secure the shaft to the eccentric. Just make certain you have the orientation of the Drive eccentric assembly (part 11) correct and you DO NOT glue the Drive wheel assembly (part 10) to any part.
10- Drill out the Drive eccentric assembly (part 11) where the roll pins previously were. The hole diameter must be slightly larger than the diameter of the wire you're going to use. Drill completely through the holes and the shaft of the Drive eccentric assembly (part 11) and then continue until you've drilled through the eccentric making 2 through holes. Reason for the through holes- the Drive eccentric assembly was poorly designed and not readily serviceable. The “thin” side of the eccentric” will not be needed to support any torque loads. The longer hole and new pinned shaft will provide much better strength and will be easy to repair if it ever fails for you again.
11- Drill out the Drive eccentric assembly (part 11) shaft and Drive lever handle with the same diameter drill bit as in step 10.
11a- Cut 2 pieces of wire to fit the holes. Trim them to fit into the drilled holes
12- Correctly orient the Drive eccentric assembly (part 11) to the shaft of the Drive eccentric assembly
13- Reassemble the Drive eccentric assembly (part 11) to the Back mounting plate assembly (part 2)
14- Reattach Drive lever handle (part 9) and install new pin
14a- Reinstall Belt (part 5)
15- Reattach Support plate (part 4) with 5 screws (part 3)
16- Verify that the Drive lever still works
17- Snap Drive Ring (part 1) back on to Back mounting plate assembly (part 2)
17a- Reattach Wheel autopilot to wheel- hex screws are metric
18- Reattach Autohelm drive motor
(parts 25, 32) to Back mounting plate assembly- (part 2)
19- Reattach the power cored to the drive motor- DO NOT POWER UP THE AUTOPILOT.
20- Engage the Drive lever and turn the wheel. Does sound like the autopilot motor is turning? If the answer is “YES” then disengage the Drive lever. Does the wheel turning freely with no sound of the autopilot motor? If the answer “YES” you succeeded.
21- Apply power to the Autopilot and see if it works properly.