ST4000 Autopilot ratchetting

[Bob Kuba]

Another item to check.

The snap-ring on my steering shaft failed and fell out unnoticed.
I did notice that the Edson nut holding the wheel on was loose, so I tightened it up.
Then I started having problems with a sluggish autohelm and noticeable binding sounds coming from the steering mechanism.

The problem was that when I tightened the Edson nut, I forced the wheel farther onto the shaft than it was designed to go. The snap-ring is there to stop it from going too far. As a result, the stationary pin that inserts into the autohelm ring was binding up the entire unit.

This is how the snap-ring should look.





This is what happens when it fails.
Notice how far the wheel was pushed onto the shaft by tightening the nut.

[Hawk]

Here's a happy ending...........

After reading Tom/Julandra's excellent post below on the drive unit I took it apart again and located the "idler pulley". After a little PB Blaster the adjusting nut loosened and sure enough I could turn it to loosen off the belt. I had mentioned that the service guy said the belt can get a little gummed up. Well sure enough there was a small amount of substance on the belt and drive unit where the belt slides.

I took some 1200 grit sand paper and went over the belt and drive unit slide edge. That combined with loosening the idler pulley has resulted in a very smooth action on the wheel with the clutch off.

I also had problems with the control unit at the same time (no idea why both units crapped out in the same week). Turns out testing with the volt meter indicated some some possible wiring issues. I resoldered the plug wires (its a non standard set-up)and then found two wires in the recepticle end that needed soldering. Ran it for a day fine. Then next day it didn't power up so apart came the control unit yet again and and the power connector had popped off, perhaps with the handling. A little adjustment and voila, back in business.

The 4000 tracked very well and seems good as new (cross my fingers). So don't give up on those old pilots yet.....Check your wiring, check the control unit power connector, and and any drive unit ratcheting can be corrrected easily.

Again thanks for the great info from everyone.

Hawk

[Wayne]

This weekend I started having the opposite problem from the beginning posts of this topic.  When engaged, my motor started running but was unable to turn the wheel to control heading in anything more than a light breeze.  I'm guessing that my problem is most likely the opposite--I need to tighten the idler?  Thanks for advice and figured better to continue this thread than start a new one . . .