During extreme severe use of our CMC Jackplates we sometimes encounter unusually strong side forces applied to the actuator.
Example. A Ski boat with a 300HP supercharged Outboard racing forward at 100mph, towing 2 skiers, decides to do a round the buoy U turn at the end of the course. Remember, this is a race, so any lack of pace is for losers. The driver does not slack off the throttle, instead he just drops the Jack Plate to give the prop plenty of water and yanks it over. The CMC Hi Speed power pack handles the action OK, drops down in the bend and is then powered straight back up again once the boat is facing forward. The forces created when the outboard is turned to go hard left/right, fighting a boat that still wants to drive forward, which in turn is being dragged back or/and sideways by the weight of the skiers, is enormous.
Remember, the water is never calm in these situations, as its being churned up by other boats and skiers, this just makes the jolting and the jumping more urgent. All of these forces are concentrated fair and square between the two sliding plates of the PL-65 Jack Plate. On occasion these forces have been transferred a little to sharply to the actuator, so that the fine tolerances within this pump become compromised. Result, the ram is able to crush the Teflon spacer O ring in the seal pack and allow itself to grind on the valve body during the down/up operation.
We have a fix for this situation. We take new valve blocks for the actuator, machine them to a very fine tolerance and fit the ram aperture with a full length sleeve and seals. This gives the ram full support as it slides through the valve body, making it impossible to bind. Cost of the kit, which involves dismantling your unit to change over to a prepared valve body, the supply and machining of that valve body etc is $395 plus postage. A small price to pay when going racing. Our shop carries out all changeovers. No parts are sold individually.