Autopilot repair and compatibility

Rocket1

Rocket1

.
Jan 12, 2012
83
None None Bellingham, WA

Evening all-

I have an ST4000+ wheel drive autopilot that seems to be fading away. The wheel drive started binding and making some racket, so I removed it and disassembled it to diagnose the issue. Seems that one of the internal guide wheels is broken and missing, causing the two "halves" of the drive ring to not want to stay aligned correctly. It looks like the guide wheel has been gone for some time (probably since before we purchased the boat), and that the rest of the unit finally has worn out to the point where the damage has reared its ugly head.

So, after much surfing and investigation I'm still left with the following questions.

Is the drive ring from a S1 unit (successor to the 4000+) compatible with the 4000+ control head? I've read conflicting information on this one, though I'm leaning towards believing that it is compatible. I've even tried to find a compatibility chart without any luck.

Does anyone have any comparative experience with the 4000+ drive (black) and the S1 drive (grey)? I have read that the S1 is more robust, but others have posted as having issues. The S1 drive is a bit more expensive, but if it rates out as a better more reliable unit then it may be worth the extra dollars.

And last but not least, does anyone have a line on a good deal for a new (or even good used) drive unit that they could steer me toward?

As always, love the forum and appreciate all of the information and help.
 
woodster

woodster

.
Sep 15, 2009
6,243
S2 9.2a Fairhope Al
i think that you will find that the drive wheel is just that a wheel a belt and a motor it take commands from the control head in the form of 12 v power and that is all so having said that you should be able to use the s 1 with good success.....

regards

woody
 
Ted

Ted

.
Jan 26, 2005
1,272
C&C 110 Bay Shore, Long Island, NY
Rocket 1, The S1 wheel drive is commonly referred to as the MKII Wheel Drive and is definitely compatible with the Raymarine/Raytheon ST4000+ autopilot control head. Raymarine recommends replacing the original MKI (black) wheel drive with the MKII (grey) wheel drive when it's beyond repair. The cable connection is the same but the mounting post on the pedestal is different. You may have to replace it too if it's too short.

If you opt to upgrade to the MKII wheel drive, I would be interested in buying your broken MKI drive. I could use some parts to make some repairs to mine. Drop me a note off line if you're interested in selling it.
 
Levin

Levin

.
Apr 7, 2007
163
Hunter 340 San Diego
Rocket,

I also have a Hunter 340 that came with the ST 4000+ when I bought it in 2005. My drive didn't last nearly as long as yours so you can be happy that you are only now dealing with this issue. As others have said, yes, the new MKII (grey) drive ring is compatible with the ST 4000+ Autopilot. You can buy this and replace the old one.

Now the problem you will find is that the new MKII drive ring does not have the exact same "footprint" as your old black MKI drive. This will be a problem because your boat has been modified by having a hole drilled in the cockpit pedestal to accommodate the drive motor off the back of the ring and the new MKII drive won't quite fit in that hole. You will have to drill another slightly away from that one and then fill in the part you don't need (I did mine using Starboard and West System Epoxy. It's annoying to do but can be done.

The other problem I've had with wheel mounted autopilot motors in general on the 340 is that I've had to replace about 3-4 of them due to the force of waves (often when sailing in following seas) pushing the rudder hard over and the autopilot trying to fight this force and ultimately shredding the internal gears. I had this happen with both the MKI and MKII drives. Now if you have owned your autopilot for many years and have only now had any significant problems with it you are unlikely to find this problem with the MKII drive. I think I have had this problem due to where I sail (SoCal) and it has almost always happened on the way home from Catalina (following seas going southeast from Catalina to San Diego). For what it's worth I've never had it happen when sailing on the San Diego Bay where wave action is not a concern. So if you sail in protected waters most of the time you shouldn’t have to worry about this.

However if you want to be absolutely sure this doesn't happen to you (as it can be expensive to replace a drive motor as you are coming to realize) I would consider a below decks unit.

Take care,
-Levin
 
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