Rebuilding a Lewmar Ocean 44 electric drive gearbox

These units are so-called “lubricated for life”. the question is what their idea of “for life” is… ours is from 2006 so 20 years old and very little use so shouldn’t be worn out. The sound it made however indicated major trouble.

Investigation showed water ingress due to a failed seal. Crazy. We decided to take it apart for repair rather than replacing it, which would cost $1,100.-

We replaced both main bearings with their seals and the two worm shaft bearings with one seal. Also I had to make a new paper gasket as one ripped during disassembly. Total cost of parts was around $50. To be honest, I also spent around $250 on tools as we are doing many similar projects.

I also used a bunch of contact cleaner for the motor and that brings me to the oil. These gearboxes come filled with ISO 150 PAG oil, with is a glycol based ling life oil, very good. Unfortunately, you have to buy 5 gallons at hundreds of dollars while you only use half a pint or so. So I decided to switch oil to an ISO 150 PAO oil. This oil is not compatible with the old oil, which isn’t a problem as we take everything apart and clean it very well. We use an ultrasonic cleaner.

The pictures above show the steps of assembly. You first install the worm shaft with new bearings. Next you insert the worm wheel and start the two end caps with a couple screws, testing movement while bit by bit bringing everything together. You set the main bearings onto the worm wheel shaft by tightening the end cap screws.

Once everything is together, the oil seals are installed and I do a final test by inserting the rotor with shaft key and turning it. Even without oil the operation is smooth and I count about a 24:1 reduction of this gearbox. Next is the motor…