Off-road driving creates a whole set of unique requirements for shock absorbers. Basically, you want the same off-road characteristics as on passenger car shocks; control for good cornering and driving as comfortable as possible. However, for off-road riding, you also want good suspension flex.
Lifted 4X4s, which have much heavier tires, accumulate more heat. And if you plan to drive at high speeds, such as desert racing, then your shock absorbers are working a lot harder, causing a lot more heat.
excessive heating
This heat buildup puts a couple of demands on the shocks you need for your lifted 4X4. Both are related to adding more oil to the shock. If the shock oil overheats, it can foam and rupture. When this happens, the shock can no longer do the job it was designed to do.
The first difference to 4X4 shocks is that they have much larger bodies. The length is also increased for lifted vehicles, but the diameter of the shock body also increases, depending on the space available under the vehicle, to increase the amount of oil it can hold.
The second way to increase oil volume is to add a remote oil reservoir. This option was created specifically for off-road racing and has become a popular solution for all types of 4X4s.
A remote reservoir allows you to use a smaller diameter shock body, while increasing oil volume by keeping it in a separate reservoir that is connected to the shock by a hose or tube. The separate oil tank also allows for better heat dissipation.
Coilover Damper
A coilover shock is a type of shock you will often see on modified 4X4s. This type of shock combines a shock absorber with a spring, all in one unit. They are popular in custom setups because you can combine both components while using the same amount of space.
Coilover shocks also allow the use of longer springs than a traditional coil spring suspension because the springs are fully contained. You can easily change the springs to change the spring tension or “frequency” as it is called.
You can also add springs for a double or triple rate spring by adding more springs with different frequencies in the winding set. This will give you a smoother ride through the first few inches of compression and a more aggressive spring rate for situations where suspension travel is beyond the normal range.
Nearly all of today’s light-duty pickup trucks come with coil-over shocks direct from the factory. This has created an opportunity for traditional shock companies to offer a combination of an upgraded shock and lift in one component.
shock valve
The choke valve is usually designed specifically for each individual application. For example, a high-quality shock to fit a truck that lifts six inches has been valved to accommodate the larger tires and handling characteristics of that vehicle.
Some shocks also come with user adjustable valving. This allows you to soften the blows when you want, such as with rock crawling. And tighten them up for towing or general highway driving.
