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What Are Hydraulic Bump Stops?

Keep Your Suspension Protected

Sep 11, 2020
Hydraulic bump stops—often referred to as air bumps or nitrogen bump stops—provide the ultimate in protection from hard bottoming situations for your off-road rig. To fully understand what makes a hydraulic bump stop unique, we must first take a look back at what a bump stop is and how it works.

What Is A Bump Stop?

Every type of suspension system on nearly all vehicles built includes some sort of bump stop. These simple devices are used to protect the vehicle when the suspension reaches full compression when encountering a bump or dip in the road surface. In the case of trucks and SUVs, most bump stops are mounted to the frame and make contact with the lower control arm and/or axle tube (for solid axle vehicles). However, bump stops can be found inside the vehicle's dampers, on the shock shafts, on one or more of the control arms, or basically anywhere that metal-to-metal contact can be prevented.

What's the Purpose Of A Bump Stop?

The job of a bump stop, no matter the type or mounting location, is simple. These devices are used to prevent metal-to-metal contact of suspension and/or chassis components. Allowing suspension components to bottom out uncontrolled would lead to catastrophic failure.
Photo 2/11   |   002 What Are Hydraulic Bump Stops Pickup Truck And Offroad Bump Stops

What Are Bump Stops Made Of?

Traditional bump stops can be made of a variety of materials, depending on damping need. Most often factory bump stops are made of rubber. Another material common to pickups is microcellular foam. This type of foam rubber absorbs impacts well and acts almost progressive in the way it stiffens as it's compressed. Many aftermarket bump stop manufacturers choose polyurethane for durability and its ability to be injection-molded.

Check Out ICON Vehicle Dynamics Ford Raptor Hydraulic Bumpstops

What Is A Hydraulic Bump Stop?

Hydraulic bump stops, at their very core, are small shock absorbers. The difference, however, is that while one end is attached to the chassis, the other is left free floating. Hydraulic bump stops come in many sizes, with bodies typically ranging from 2.0 inches to 2.5 inches and with a stroke from 2.0 to 4.0 inches. Hydraulic bump stops use a shaft that is much larger than a typical shock absorber to handle the increased loads. Hydraulic bump stops are also oil filled and charged with nitrogen, and most have adjustable shim packs just like a shock absorber.
Although the term "air bump" has become common, it's largely incorrect. Hydraulic bump stops operate as a mono-tube shocks absorber and not as an air-shock. They get the term "hydraulic" because they use fluid, typically light weight shock oil, to absorb suspension energy instead of plastic or rubber stops.
Photo 3/11   |   006 What Are Hydraulic Bump Stops King Hydraulic Bump Stops On Race Truck

Who Needs Hydraulic Bump Stops?

Hydraulic bump stops are best suited for customized off-road vehicles that are designed for going fast over large bumps. Think more racing-oriented than rock crawler, though they can certainly be used in most applications. The largest issue with running hydraulic bump stops is mounting and fitment. All require custom mounting and oftentimes are far larger than a more standard rubber bumper.
Because hydraulic bump stops are far more robust than rubber, they hold up better under conditions that demand their frequent use. They are also a tunable part of the suspension, as their rate of compression and rebound can be changed by adding or removing nitrogen pressure or by adjusting the internal valving.
Photo 4/11   |   007 What Are Hydraulic Bump Stops Jeep Gladiator Mojave Hydraulic Bump Stop

Do Any Factory Trucks Have Hydraulic Bump Stops?

To date, the only truck that has come from the factory with an OEM hydraulic bump stop is the Jeep Gladiator Mojave. The Gladiator Mojave, Jeep's go-fast desert-oriented pickup arrives with Fox 2.0-inch hydraulic bump stops from the factory. These are mounted inside the front coil springs and are attached to the frame. With manufacturers offering vehicles with more and more off-road capability, we wouldn't be surprised to see more factory hydraulic bump stops in the future.

Can I Add Hydraulic Bump Stops to My Truck?

Short answer: Of course! With the right tools, anything is possible. However, not all vehicles are conducive to adding hydraulic bump stops (or need them). The easiest is adding hydraulic bump stops to the rear of pickups, such as Ford's F-150 Raptor, and to the front of Jeeps, such as the Wrangler or Gladiator. Kits exist that make adding hydraulic bump stops to these vehicles actually quite easy.

So, What's the Downside?

Aside from the cost, which can easily exceed ten-fold what a rubber bump stop costs, hydraulic bump stops are also noisy and require more frequent servicing. And, if your rig isn't setup for them properly (shock tuning, etc. ), they can also make the ride worse instead of better. Make sure to properly consult with the manufacturer of your suspension, as well as the hydraulic bump stop manufacturer, before committing to them.

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