A Guide To The Types of Shocks & Struts 

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Driving a vehicle without suspension would be torture and probably cause harmful whole body vibration. Thankfully, today there are well-designed shocks and struts available for every kind of vehicle and for a variety of driving conditions.

If you want to take your road truck off-roading, you can swap out the factory fitted shocks and struts for specially designed ones that provide you with a better off-roading experience. Whatever activities you enjoy in your vehicle, it is important to ensure that you have good-quality shocks or structs for a smooth and safe ride.

However, many people are confused by shocks and struts. The two terms are often used interchangeably even though they are different things. Also, there is a broad range of shocks and struts available, so it’s difficult to know what’s best for your vehicle. There’s no need for you to remain confused.

The difference between shocks and struts

There are both structural and functional differences between shocks and struts, but both can be used as part of a vehicle’s suspension.

As its name suggests, a strut functions to support your vehicle’s frame above the wheels. It is an integral structural component that maintains your vehicle’s stability with its stem and reinforced body. A strut comprises a damping unit that serves to reduce the speed and repetition of any vertical movement and a coil that provides support.

On the other hand, a shock absorber does not provide support. Instead, it serves as part of your vehicle’s suspension system to convert kinetic energy into heat and so dampen vertical movement. Commonly, struts are used on a vehicle’s front wheels and shocks as part of the suspension on its back wheels.

Types of shocks

All shock absorbers work using a hydraulic system filled with oil or gas. Modern designs often contain a combination of both. The two common varieties of shock absorber are twin-tube shocks and mono-tube shocks. Variations on these include remote reservoir shocks and coil-over shocks.

Twin-tube shocks

Twin-tube shock absorbers consist of two oil-filled cylinders nested together. A piston is located inside the central “pressure tube” or “working tube” cylinder. The gap between this inner cylinder and the outer cylinder is called the “reserve tube” and contains the excess oil not held in the central cylinder.

twin tube shock absorber

When the piston is pressed up or down by a bump on the road, its movement is restricted by the oil pressing against it from both sides. However, small holes in the piston or valves allow slow movement. Thus, the shock resits rapid changes and dampens the shaking of the vehicle.

This resistance transforms kinetic energy into heat within a twin-tube shock absorber. In better designs, the reserve tube is filled with nitrogen gas. Such designs are sometimes called twin-tube gas-charged shock absorbers. The gas reduces the aeration or foaming in an overheated shock absorber that leads to a significant reduction in dampening.

Twin-tube shocks are typically low pressure and the most affordable shock absorbers. Their twin-cylinder design and low pressure make them relatively durable and resistant to damage from road debris. That gives twin-tube shocks a long lifespan.

Mono-tube shocks

These shocks consist of a single gas and oil-filled cylinder, the “working tube”. However, this cylinder contains two pistons. The upper piston is connected to the rod and termed the “working piston”. The lower piston divides the lower part of the cylinder in two and is called the “floating piston”.

mono tube shocks mono tube shocks

The oil in the top part of a mono-tube shock is sealed away from the nitrogen gas in the bottom by the floating piston. The dual action of these two pistons when you hit a bump in the road results in less aeration and superior heat dissipation. They provide better dampening over rough road surfaces.

Mono-tube shocks are high-pressure and more expensive than twin-tube shocks. Their single tube design means that they tend to be longer than twin-tube shocks. The single skin design and high pressure also make mono-tube shocks more vulnerable to road debris.

Remote or external reservoir shocks

The most common problem with shock absorbers is a build-up of heat that causes aeration resulting in a bumpy ride. One way to reduce this problem is to increase the amount of oil in the shock by attaching an external reservoir shock, sometimes called a remote reservoir shock.

reservoir shocks

Remote reservoirs can either be attached directly to the shock in a piggyback style or connected by a section of high-pressure hose. Piggyback external reservoirs require space for mounting. Hose-attached external reservoirs are more flexible because the extra reservoir can be mounted separately from the shock.

External reservoir shocks are expensive, but they provide a superior ride when things get extra rough. They are typically used in high performance or off-roading vehicles where high-performance shocks are an advantage.

Coil-over shocks

Both twin-tube and mono-tube shocks can be purchased encased inside a helical road spring. These sprint-assist or coil-over shocks provide dampening and suspension in one. They are a common component of MacPherson struts.

MacPherson struts

MacPherson struts are the most common type of automotive struts. They are frequently found in a modern vehicle’s front suspension. MacPherson struts combine a shock absorber, a supporting coil spring, and the steering arm. These struts are durable and sturdy.

Steering stabilizers

Steering stabilizers, or steering dampers, are not the same as shock absorbers, but they perform a similar task. While a shock absorber dampens the vertical movement of your vehicle, a steering stabilizer dampens the horizontal movement. A steering stabilizer enables smoother steering when you’re carrying heavy loads or off-roading over rough terrain.

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Robert Baker

Robert is a content writer and editor at Outside Pursuits where he shares his love for the great outdoors. He also writes in-depth travel blogs for other websites around the world. Robert is passionate about the environment and uses his writing to educate people about the advantages and importance of sustainable living. Robert enjoys creative writing. In 2009, his children’s novel Sally Hemings & the Good Associates won the Children’s Fiction section of the You Write On Book of the Year Award.

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