Shock Absorbers

What a shock absorber does

A shock absorber is a damper. The spring holds the vehicle up, and the shock controls how fast that spring moves. Without working dampers a truck bounces repeatedly after every bump, tires lose contact with the ground, and braking and steering suffer. Off-road, shocks also absorb heat from constant motion, which is why fade becomes a concern on long, rough stretches.

Key specifications to compare

• Collapsed and extended length: These two numbers set the travel (extended minus collapsed). The shock must be long enough that it never limits suspension travel or bottoms out before the bump stops do, and short enough that it is not the first thing to run out at full droop.
• Mounts: Bar pin, stem, eyelet and bolt-in ends are not interchangeable without hardware. Match both the upper and lower mount styles to your vehicle.
• Body design: Monotube shocks usually run cooler and resist foaming better. Twin-tube shocks are common as stock replacements and are often quieter and lower in cost. Many listings state the body diameter, such as a 46mm smooth body.
• Reservoir: An external reservoir adds oil volume and gas capacity, which helps with heat in hard or sustained use.
• Shaft diameter: A larger shaft is generally more resistant to bending.

Choosing for your use

For a daily driver with a modest lift, a quality non-adjustable monotube or gas-charged twin-tube shock sized for your lift height is usually enough. If you tow, carry a heavy bumper and winch, or run fast desert roads, look at larger bodies, reservoirs and tunable valving. Pair the shock with the right spring rate; a shock cannot make up for a spring that is too soft or too stiff for the load.

Fitment and installation

Shocks are specific to lift height, axle and whether they are front or rear, so confirm fitment for your exact year, make and model and check the manufacturer's specifications. Replace shocks in axle sets, since one new and one worn shock gives uneven handling. Support the axle before removal so it cannot droop and stretch brake lines, and tighten fasteners to the specified torque. If you changed ride height, have the alignment checked afterward.

A final point on tuning: if a shock offers adjustable damping, change one setting at a time and note the result on a familiar road. Heavier loads, such as a winch bumper, roof tent or camping gear, often call for firmer valving than an empty truck. Inspect boots, bushings and mounting hardware at every oil change, since a worn bushing can mimic a failing shock.

Mistakes to avoid

The most common error is choosing shocks by brand or price without checking the length numbers. A shock that is too short lets the axle droop until the springs unseat or brake lines tighten, while one that is too long bottoms out and can bend the shaft or damage the mounts. Measure from mount to mount at ride height, then at full droop and full compression, and compare with the listed collapsed and extended lengths.

• Do not ignore worn bushings, since new shocks with tired bushings still clunk.
• Do not use a shock as a travel limiter; bump stops and limit straps do that job.
• Do not install shocks with the vehicle hanging from the frame and the springs unloaded, because mounts then sit in the wrong position.

Test drive on a familiar road after installation and listen for rattles before heading onto the trail.