Autohelm 3000 Owners: Roller Bearing Source; Overhaul

[Paul Eisenberg]

If you need replacement roller bearings for the output shaft of the Autohelm 3000 belt drive unit which I believe same drive unit on several other models, here is a source:

Nordex Inc.
426 Federal Road
Brookfieldk, CT 06804
203-775-4877
Welcome to Nordex.com
info@nordex.com
item is EPSM6004 (stainless dowel pin)$1.16 each plus shipping
The motor/drive unit uses 10 of these

Discussion:

I bought a Dufour 31 this summer and it came with a very used Autohelm 3000 autopilot that had never been installed on this boat. I took it home and bench testing the unit I found the drive was frozen and would not rotate. I unscrewed the tapered back shell of the drive unit exposing the motor and separatling it fropm the planetary drive unit. With the motor disengaged from the planetary drive the motor responded fine to commands in both directions. I very carefully placed a drop of oil on each motor bearing using a fine point needle oiler and I checked the motor brushes which were fine, then set this aside for re-installation later.

I pressed out the retaining pin that holds the plastic belt drive gear to the planetary drive output shaft and quickly found the bearing inside the belt drive gear to be completely corroded and rusted. There are 10 short steel roller bearings held in a plastic cage. These roller bearings run in a space inside the plastic belt gear and on a bronze bushing that is part of the case and surrounds the planetary unit's output shaft. This bearing is the one that actually carries loads imposed on the motor/drive shaft when the drive belt is tightened to perform steering and is very important. These roller bearings were completely rusted beyond repair, and frozen in place. Salt water corrosion was obvious. The plastic cage and the bronze bushing around the planetary gear output shaft both cleaned up effortlessly, so I concluded that if I could locate replacement roller bearings I could repair the unit. I decided to look for stainless roller pins instead of hardened steel for better corrosion resistance, and I eventually found these at Nordex, per the above. They fit perfectly.

After removing the plastice belt drive gear and its internal roller bearings, I opened up the planetary drive itself and carefully removed the three layers of planetary gears and spacers, laying them out in such a way that cleaning and re-assembly would be logical and obvious. I found some minor corrosion and that the gear lube had hardened. I cleaned the housing and each part with a gentle solvent and then used a very fine emory cloth to touch up each metal shaft where there was any sign of rust or debris. The worst corrosion was found all the way at the bottom where the main output drive shaft exits the housing towards the plastic gear drive.

{Most people might want to skip the following step in which I performed a little "improvement surgery" that is likely not needed. For the adventurous, I'll describe this separately below, but it is an experiment and I would not recommend it unless you have the experience and the right tools to do machining. I highly recommend you skip this step unless it is only way salvage your unit, which was the case for me due to the extent of the corrosion on the case itself allowing water to penetrate inside.}

For re-assembly, I lubed each shaft and gear and re-assembled in reverse order of my dissassembly. Once completely assembled, I lubed and installed the new roller bearings into the original plastic cage, and lubed the bronze bushing, then re-installed the plastic belt drive gear, aligned the retaining holes in the plastic gear drive and the shaft, and carefully pressed the retainer pin back into place. I re-installed the motor and screwed the tapered back of the case onto the plantetary gear unit. With this minor overhaul the unit now responds properly in both directions to commands from the control unit.

Next I need to install the autopilot in Dauphine for the first time. We'll see how that goes.

I hope this is helpful to anyone out there struggling with an Autohelm motor/gear drive unit.

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Ok: For those interested in the {"surgery"} mentioned above. I noticed that water had entered the planetary gear case from the output shaft. The case around the output shaft was badly corroded, and looked like an easy source for future water with no obvious way to seal it. I could not determine any means of keeping water from entering along the shaft without modification. So I used a drill press and precision centering vice to keep everything perfectly true, and in a two step process I bored out the shaft hole in the case just enough to press fit a new bronze bushing I bought and create a larger partial depth recess to accomodate the flange on the exterior face of the housing. I bored the smaller center hole first, all the way through, and the larger partial depth recess from the outside. I was careful to ensure that both ends of the press fit bronze bushing sit flush with the face of the case on both the inside and outside faces. This busing is not intended to carry the shaft loads, but rather to put a small o-ring onto the output shaft between the plastic gear drive and the bronze bushing flange. There is very slight pressure on the o-ring and I expect this to prevent future water intrusion. Be very careful to ensure the end of the bushing inside the case does not extend further in than the original housing or it will pinch the planetary drive gear assemblies. The preceding will prove to have either improved the original design, or destroyed the case. Time will tell.

[DeepFrz]

Wow, great post, thanks. Any pictures?

[Paul Eisenberg]

Two photos (attached) showing the corroded roller bearings and cage assembled and dissassembled, but none of the tear down. It's not currently handy, sitting in the boat an hour away. If you want to see the new bushing aspect I could open it back up and repeat for pictures, or for the general overhaul I've got another defective unit coming any day that I picked up on E-bay. Says it's not working and I assume it has a similar problem. I'll take pictures when I tear it apart to illustrate the text.

Paul

[Paul Eisenberg]

DeepFRZ

Here are more pictures of the motor/drive dissassembly, the inserted new bushing and O-ring. Reassembly is just reverse order.

Paul

[DeepFrz]

Thanks Paul, that's a great resource for anyone else needing to repair their auto pilots.

[Kym]

Hello Paul, yes that is an excellent post .
So good I am wondering if you could find time to help me with some info? My Auto helm 3000 started send us around in ever decreaseing circles one afternoon on our "pond" in a stretch which is only about half a mile wide. On dismantling I have found that several wires had come adrift from the end of the drive motor and the resistors and the "pot" are burnt.
Do you know where I can get a service manual ( not an operating manual) to work out which colour goes where? And the value of these items.
Or is it easy to check yourmotor and describe the connection positions? I have still not found a supplier for the "pot" but will keep trying .
i gave the unit to our local TV technician but he could not sort it. The nearest Marine electronics shop is 350 Km away . single handed sailing without an autohelm is difficult

[whewididit]

Hi Paul,

Happy Holidays! My motor and controls work fine but the belt slips alot. Any thoughts?

[Jim Cate]

Originally Posted by whewididit

Hi Paul,

Happy Holidays! My motor and controls work fine but the belt slips alot. Any thoughts?

There are at least two methods of lessening/eliminating slippage between the belt and the wheel drum:

1. For the faint of heart, spraying the belt and drum with v-belt "anti-slip" dressing (available at auto parts stores) will help lots.

2. If you really want to stop slippage, get an old belt and glue a section of it around the drum with the "teeth" outward. These then engage the teeth on the drive belt almost like a gear, and NO slippage will be possible. The down side of this is difficulty in disengaging the pilot, but it can be done.

A third possibility is to simply rough up the friction surface of the drum... the original knurling does wear off in time.

By the way, the above (rather old) posting is excellent general advice about dealing with these poorly engineered units.

Good luck with it

Jim and Ann s/v Insatiable II lying Towlers Bay, NSW, Oz