Monotube vs Twin Tube Shocks

A monotube is usually the better choice when the vehicle tows or runs heavily loaded for long periods, because its larger piston and direct cooling keep damping steady as the oil heats. The valving matters as much as the design, though. A monotube valved for a light car will still feel underdamped behind a heavy trailer, so it is worth asking for a valving specification that matches the laden axle load. Bear in mind that shocks only control movement and the springs carry the weight, so if the vehicle sits low under load, it is the springs that need attention. A stiffer shock will not bring the ride height back.

Usually yes, provided the replacement matches the original's extended length, compressed length and mounts. The high gas charge pushes the rod out with a few hundred newtons, which can raise ride height by a few millimeters, and the longer body may reach the bump stop sooner. You should also fit the same design to both sides of an axle, so that the car behaves the same way on each side.

Store twin-tube shocks upright where you can, and prime them before fitting. A twin-tube left on its side lets gas or air move into the pressure tube, which causes a soft or noisy first few strokes. Hold the shock rod-up and work it through its full stroke three or four times. A monotube needs no priming, because the floating piston keeps the gas and oil apart in any position. With either type, never clamp the body in a vise or grip the polished rod with pliers. A crushed tube will jam the piston, and a scored rod will soon wear through the seal.