$txt['youtube'] = 'YouTube'; $txt['youtube_invalid'] = '#Invalid YouTube Link#'; Servo Housing Maintenance Check

Shop Talk > Mokai ES-Kape

Servo Housing Maintenance Check


I wanted to give a heads up to any es-kape owners out there still running the servos.  I typically pull the engine and inspect everything every couple trips, however this year I had no issues and ran my boat between 30 and 40 day trips since April.  I pulled the engine once to change the oil, but otherwise I just beat the crap out of it and it saw weekly (or more) use this whole year.

I went to break everything down to winterize it and noticed my steering servo was very loose on the housing mount.  I had been noticing the boat wandering more than usual the last couple months, where after I made a turn, it wouldn't straighten out completely.  It turns out that about half of the screws in the servo housing had vibrated so much they stripped the threads out of the magnesium servo housing.  (Second picture housing threads circled in red)  It was hardly hanging on and explained the excessive wandering after a turn.  It was so loose, the grease from the gearbox was working its way out of the screws and past the mounting plate. (first picture)

I was thinking the fix would require tapping deeper, or larger threads, possibly replacing the servo or the housing, or scrapping it all and switching to Tom's manual conversion.  As it turns out, the threads in the servo housing were much deeper than were being used and all I needed was longer screws.  The stock screws were 8-32 3/8" and there was only about 1/8" to 3/16" of those threads making it past the mounting plates and into the servo housing threads. That plate is about 1/8" thick and a proprietary Mokai part, so I believe they just reused the screws that came with the servo instead of putting longer ones in to accommodate the thickness of their plate. 

To fix it, I just cleaned out the threads in the housing and picked up some 8-32 1/2" screws to put it back together. (picture: new screws next to original screws)  I also used black RTV around the whole thing to make it a little more waterproof and thread locker on all the screws.

If anyone is putting a LOT of hours on an es-kape (weekly use) keep an eye on the steering servo.  Had I known this would happen, I would have replaced those housing screws with 1/2" ones before they stripped out the housing.  If it happens again, the fix will be way more involved, and had I gotten longer screws grabbing more threads in the housing before it stripped, it likely would have never happened.

Glad you were able to fix it, but not all the servos had the same design. There were a few different versions over the years, each with their own problems. They are great little servos, just suited for the hobby sector and shouldn't have been put on a manned boat. You know how to maintain it so you should be ok as long as heat doesn't get it eventually. Good job on the fix and thanks for sharing!  \./8

Thanks Tom, I should add this is a 2015 es-kape if they are different throughout the years.  I took both ends off to reseal with RTV and didn't see any signs of heat damage yet.  With the amount of abuse I've put this boat through, I hope that means I'll be fine, but time will tell.

I found a better use for these servos. Using three of them on this project. I plan on starting a new thread with all the episodes for those who wish to follow along, but I thought you would get a kick out of this here.  :D



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