Your Truck Will Thank You for It.
It's out there somewhere, waiting for your truck. When you find and install it, your truck will feel transformed. The perfect shock needs to fill a tall order. It should let your truck fly smoothly down the freeway. You'll barely notice the cracks and gaps in overworked urban freeways. When you arrive at your off-road destination, that same shock will accommodate your every whim: Fly around the track at Rialto Offroad Raceway, then turn a few laps out at the MDR Barstow course, followed by a quick Baja prerun. After all the dirt action, that same perfect shock will guide you smoothly home with the flick of a turn signal as you return to the pavement. Tuning and changes in setup from one driving situation to another would be minimal, if needed at all. The perfect shock will absorb landings, small and tall. It will let your truck corner without body lean or wallowing.
While most of us are far from this blessed state of suspension superiority, we set out to gather some information that would help us on our journey. We began by seeking some wisdom about shocks. What shocks are the best? What shocks are the worst? What can be done to make a shock work better? "The best question to ask," said suspension-maestro Kreg Donahoe, "is how much suspension performance do you want, and at what cost?"
It seems that shock hierarchy begins with a basic twin-tube damper and goes up from there. A twin-tube shock has an outer can, an inner can, and a sheet of foam separating the two. Oil serves as the damping medium. Twin-tube shocks are generically valved with an inertia damper - the more force they are put under, the more they resist movement. Twin-tube shocks are prone to heating up and fading. The fade comes when atmospheric air mixes with the oil and turns it into a hot bath of foam, which has no viscosity and allows no motion control. Another twin-tube disadvantage is the minimal oil volume and small piston diameter. This comes as a by-product of running a second tube inside the main shock body.
Fortunately, there are more options available now than ever before, and we're not talking about which color of shock boot best matches your blingin' paintjob.
The best shocks use a monotube construction. This means that the shock body has a single wall (no second tube inside), allowing for maximum fluid volume. More fluid means better heat dispersal, which means less shock fade. The piston diameter is larger and provides a larger area for oil flow. Another important feature is a nitrogen chamber separated from the shock's damping oil. A floating piston divides the two chambers, moving in response to input from the damper piston forcing its way through the oil.
Many of today's new shocks are rebuildable. This means that the shocks can be disassembled and reassembled with different parts that tune the shock to better suit the vehicle or terrain.
At the top of the shock totem pole, you'll find bypass shocks. These rebuildable monotube dampers incorporate yet another trick to refining suspension action. Bypass tubes, running either externally or internally, route some of the damping oil around (bypassing) a length of the main shock body, returning the oil to the main body at a specific location. One-way check valves in the bypass tubes ensure one-way flow through the bypass tubes. The advantage? Bypass tubes provide position-sensitive damping that is ultra-tunable. Since the bypass tubes are set up for one-way oil flow, separate compression and rebound bypass tubes are needed. Three-tube bypass shocks are common, usually sporting one compression tube and two rebound tubes. Bypass shock manufacturers can add additional tubes for custom applications.
A number of companies wait at the ready to help bring the collective off-road community closer to shock perfection. Here's what we found.