Replacing an ABT Trac Stabilizer Actuator

January 27, 2025

Over the past 300 hours or so, the actuator on my port side stabilizer (ABT-TRAC 220) began leaking.  I successfully ignored the problem until December 2024, when I was just lucky to be one hour from port in Santa Marta, Colombia.

While every leak would almost certainly be different, my situation began with me noticing some oil below my fuel polishing filters.  Small leaks are not horrible and so I noted the leak, but chose to simply monitor it.  While cruising in early 2024, I made no changes to my plans as there was no impact to my activity, just the consumption of a few oil absorption rags. 

During this period, I travelled from Aruba to Panama and spent some time in the San Blas Islands, and the ‘problem’ was managed by monitoring and adding small amounts of hydraulic fluid to the reservoir.  As I began my passage East and North, I was lucky to discover that the actuator was losing a lot of fluid before heading a significant distance offshore.  As I pulled into Santa Marta before Christmas, the stabilizer alarms informed me that my hydraulic fluid was critically low.  I quickly discovered that I had lost the entire reservoir during an ~24 hour journey from Cartagena to Santa Marta (and that is not a pleasant journey in December, against the wind, waves and current).

Over Christmas I had a new actuator delivered to me (to my Mail Drop in the USA, actually) and returned to the boat with the relevant parts in my luggage.  In Santa Marta there is no significant service capability for this system so I was on my own.   (Marina Santa Marta is an IGY Marina and an excellent place to put in. They do have a service capability, but it is not robust, it’s all in Spanish, and parts are sparse, coming from Barranquilla, Cartagena, or of course shipped in, but I never went down that route.)

ABT provided me with a drawing showing how the system was assembled and I had phone numbers for service personnel. Both ended up being exceptionally helpful. Below is the exploded view of a stabilizer (slightly different than the 220 installed on the N47).

 

Perhaps the first step should be to shut off the oil flow from the reservoir and disconnect the hydraulics.  (Two lines connected to the actuator). They will leak so capping them may help, or hold/tie them with the open end up.). Disconnecting these lines can be done later as well.

This is the actuator. You can see it is attached below the cover plate and so some disassembly is required.

First remove the position sensor cap (round grey in the centre, with the ground wire.)

Under that grey cap is the position sensor.  There are two 1.5mm hex bolts holding this in place.  (NEVER UNDO THE TOP HEX BOLT, REMOVAL OF THE BOTTOM ONE WILL ALLOW FOR THE REMOVAL OF THE SENSOR). It is helpful to note the location of the hex bolt because it’s position is critically important and extremely sensitive.  It will make reassembly easier.

Because I was doing this ‘blind’ for the first time it was difficult   The hex bolt is difficult to reach (you can gently twist the aluminum cover surrounding the sensor) but still seating a hex wrench was difficult   Notably that bolt is drawing a clamp together, not pressing against the axle/rod, so the access is at 90 degrees to the rod.   That took me a while, and a camera, to figure out.  I would also suggest completely removing that hex bolt and putting it somewhere safe until you are ready to reinstall it.

Once the sensor is removed, the cover plate can be removed (on a 220 there are six hex bolts holding that plate on, they have to be removed).  Notably the position sensor wire is held down with 3 or 4 screws.   If you don’t remove the wire you cannot lift the plate off completely. On Home Free, this became an issue later when I needed to completely remove that plate. The removal of the wire from the plate will also be necessary if you are replacing the bearings.

For my situation things got more difficult from here.

First of all, the cover plate does not always come off easily. 

The actuator has two pins (about 1” in diameter) that are inserted into the top and bottom plates, these are seated in two bearings, also one in the top plate one in the bottom.   That fit is likely to be very tight making it difficult to remove the plate (from the upper pin) and the actuator from the lower plate.  I am not sure what tool would be good to apply even pressure on the plate (top) or actuator (to remove from bottom plate) but a tool could be helpful.  Perhaps an inflatable balloon or mini jack of some sort.  I ended up using a crowbar to get it moving and then brute force to lift it off completely.  It could take substantial strength to remove the actuator by hand and in my case it tested my physical abilities.

Ignorance made the challenges worse from there, but can be remedied simply.  The pins on the actuator are a tight fit and sanding down the pins on the new actuator until they slide into the bearings with firm but not Herculean effort would be the correct course of action.   In my case I sanded for some time (80 sandpaper for about 5 minutes over multiple tries and 400 sandpaper for a couple of minutes to finish/smooth the pin) and still had to use use a mallet to get the pin in.   Removal will be equally difficult.  I did have to sand down the upper pin significantly to get it to slide into the bearing.  The pin should not be loose in that bearing, so go slow, remove material evenly and test often.

Note that there is a locking bolt as well that is secured with a flat head bolt (hex) to ensure everything remains in place over the clevis pin. This should be seated and secured with loctite, provided with the actuator.

Ideally the spherical bearings would be replaced at the same time but this requires a special tool and I did not want to attempt that without access to assistance.  Since I did not do that, I can’t comment on the difficulty.

Once the actuator pins slide into the upper and lower plate bearings and the plates are secured with the hex bolts, it’s time to reinstall the positioning sensor.

For this I used the help of  Daryl Wendorf at ABT.  I can’t detail it here.  Essentially you need to unlock the stabilizer control panel and spin and monitor the positioning sensor on its shaft until the appropriate parameter on the control panel says it is at ‘zero’.  This is exceptionally difficult and values +/- 100 are close enough but the closer to zero the better. 

To align the sensor at zero you spin the sensor on the axle until it gets to zero and then tighten the lower hex bolt.  The sensitivity is exceptional and this is nearly impossible but the effort must be undertaken to get as close to zero as possible.  Two people make this easier as someone reads/yells the numeric value of the parameter to you and you realign and tighten the bolt. Simply tightening the bolt will likely change the number and the opportunity for frustration is vast. Patience.

When this alignment number is as close to zero as possible (and less than +/- 100), an adjustment factor can be entered into the parameters on the control panel to accommodate this offset from zero. 

When that step is complete and the hydraulics are reconnected and the reservoir filled, turning on the system will restart the system and should bring the stabilizers back to proper function. If the ball valve on the reservoir was closed, remember to open it again.

Since completing this work I have enjoyed another 50 hours or so of cruising with everything working properly and no further leaks. It is nice to accomplish this in the wild ‘alone’. (Thanks Daryl!)