Mercury - Trim Cylinder O-Ring Kit Hydraulic Trim System Rubber Seals 87400A2. Overview. If you've spent enough hours on the water, you can feel when your trim system stops behaving the way it should. The stern doesn't lift as cleanly, the bow angle feels off, or you start seeing a bit of hydraulic film where it doesn't belong. That's usually your trim cylinder telling you it needs some attention. The Quicksilver 87400A2 O-Ring Kit is one of those small, unassuming fixes that can completely rest