Glossary

The distance between the ground (or the center of the wheel hub) and a fixed point on the vehicle’s chassis. Changing the ride height with a lift kit alters the distance between the axle and the frame, which dictates whether you need to extend your bump stops to maintain proper suspension travel limits.

The baseline ride height of a vehicle when it is parked on level ground under its normal, everyday resting weight (with typical gear, but without dynamic suspension movement). This is the critical starting measurement used when calculating custom shock lengths and proper bump stop gaps.

The amount of independent up-and-down wheel movement relative to the vehicle's chassis. Maximum articulation keeps your tires planted on uneven terrain for optimal traction.

The upward movement of the wheel toward the vehicle’s body. Bump stops are the critical limiting factor for up-travel.

The downward movement of the suspension from its normal resting ride height. It keeps your tires in contact with the ground when dropping into ruts or holes.

The harsh, jarring event that occurs when a vehicle’s suspension reaches its absolute maximum compression, causing metal-to-metal contact between the axle and the frame. Upgrading from factory bump stops is the primary way to eliminate this impact.

When suspension components compress beyond their safe physical limits, risking severe damage to shocks, fenders, or the vehicle frame.

When a tire makes physical contact with the wheel well during suspension compression. Adjusting bump stop length (such as using an extended stop) restricts up-travel just enough to prevent rubbing. Used to size your front bump stops

A critical suspension component designed to absorb impact and prevent metal-to-metal contact when the suspension fully compresses.

Bump stops that are bolted or welded directly to the vehicle's stationary chassis (the frame). As the suspension compresses, the axle moves upward and makes contact with these fixed stops. Platform Specificity: The standard factory setup for most solid-axle rear SUVs, including Toyota 4Runners, and Lexus GXs.

Bump stops attached directly to the moving axle housing or lower control arm. In this setup, the bump stop travels upward with the axle and strikes a stationary contact pad on the frame during full compression. Platform Specificity: Common on the rear suspension of Toyota Tacomas and many leaf-sprung trucks, as well as the front axles of Jeep Wranglers (TJ/JK/JL).

Small, donut-shaped bump stops that slide directly over the metal shaft of a shock absorber or strut. They act as a final, internal line of defense to prevent the shock from bottoming out against its own internal valving. Brand/Platform Specificity: Standard on front MacPherson struts (like OEM Toyota fronts) and high-end aftermarket coilovers from brands like Bilstein, Fox, and King.

The factory-installed bump stops your vehicle came with. Typically made of hard, dense rubber compounds, they offer very little give and result in harsh impacts when the suspension bottoms out.

Common aftermarket upgrades that offer a slight improvement over OEM parts but still lack advanced impact dispersion or speed-sensitive damping. Brand Specificity: Commonly associated with aftermarket replacement brands like Energy Suspension and Daystar.

High-end, shock-absorber-style bump stops filled with shock oil and nitrogen gas. While highly effective, they are expensive and require custom metal fabrication and welding to install. Brand Specificity: Manufactured by high-end racing brands like Fox, King, Radflo, and ADS. Check out Perry Parts Hydro Silencers

Advanced bump stops designed to change their resistance based on the speed and force of the impact. They offer the smooth, progressive energy dissipation of hydraulic bumps, but with the easy, bolt-on installation of a factory replacement. Brand Specificity: The core technology used by Perry Parts, differentiating them from standard static OEM replacements. Check out Perry Parts bump stops

A rigid axle that bears weight but does not receive power from the engine or contain any drive gears. This is typically found on heavy-duty trailers or older 2-wheel-drive truck front suspensions.

A suspension layout where each front wheel moves independently of the other. In IFS setups, the front bump stops are typically mounted on the lower control arms to limit the upward swing of the suspension assembly, protecting the strut and CV axles. Platform Specificity: Standard on the front of almost all modern off-road vehicles (Tacoma, 4Runner, F-150).

A mechanical term describing an axle that actively receives power from the engine to drive the wheels (housing the differential and spinning axle shafts). While often used interchangeably with "solid axle" in the off-road community, an axle can be live without being solid (like an IFS setup).

A structural term describing a single, continuous rigid housing that connects the left and right wheels. When one side compresses over a rock, the rigid tube acts as a lever, forcing the opposite wheel downward. During extreme articulation, the bump stop acts as the physical pivot point (the fulcrum) for the axle, making a progressive, energy-absorbing bump stop critical to prevent harsh metal-to-metal binding. Platform Specificity: Almost all solid axles in modern 4x4s are also "Live Axles" (hence the overlapping terms). Standard on the rear of most trucks/SUVs, and the front of Jeep Wranglers and heavy-duty trucks.

A suspension upgrade utilizing aftermarket upper control arms (UCAs) and upgraded coilovers to maximize wheel travel without widening the vehicle's track width. This is the most common setup for a standard 2-3 inch lift, where upgrading to extended travel bump stops is usually recommended to protect the new shocks but not always.

A specialized suspension setup utilizing extended control arms and longer shocks to drastically increase wheel travel for high-speed desert running. Because long travel kits completely change the factory suspension geometry, they almost always require custom-sized or repositioned bump stops to prevent severe over-travel. Brand/Platform Specificity: Highly popular on Toyota Tacomas, 4Runners, and Ford Raptors, commonly utilizing aftermarket kits from brands like Total Chaos, Camburg, and Dirt King. Check out Perry Parts Long Travel Front and Long Travel Rear bump stops.

A factory hydraulic suspension system that automatically or manually adjusts the vehicle's ride height. Modifying vehicles with AHC requires precise bump stop tuning to maintain proper suspension geometry and prevent damaging the delicate hydraulic sensors and shocks. Platform Specificity: Found almost exclusively on Toyota Land Cruisers (100/200 series) and Lexus LX (470/570) SUVs.

A factory hydraulic sway bar system designed to automatically disconnect or loosen the sway bars for massive off-road articulation, while keeping the vehicle perfectly flat during high-speed cornering on the pavement. Upgraded bump stops are critical on KDSS-equipped lifted vehicles to prevent over-compressing the expensive hydraulic cylinders during heavy articulation. Platform Specificity: Common on Toyota 4Runners, Land Cruisers, and Lexus GXs.

A traditional rear suspension design using stacked, flexible steel plates. On leaf-sprung vehicles, bump stops often mount to the axle's U-bolt plate or strike directly against the frame to prevent the leaf pack from inverting (bending backward) and snapping under extreme bottom-out loads. Platform Specificity: Common on the rear of Toyota Tacomas, Tundras, and domestic pickup trucks.

A setup where traditional steel coil or leaf springs are replaced or supplemented with heavy-duty pneumatic rubber bags, often used for towing or leveling heavy loads. If an air bag system fails or deflates on the trail, the vehicle will drop completely onto the bump stops, making high-quality dynamic bump stops critical for limping the vehicle home safely. Brand/Platform Specificity: Factory on some Ram heavy-duty trucks and Land Rovers, or added via aftermarket helper bags like Firestone Ride-Rite and Air Lift.

Polyurethane or rubber pads placed between the metal coil spring and the vehicle frame or axle seat. While they absorb minor high-frequency road vibrations and eliminate metal-to-metal squeaking, they do not absorb large impacts like a bump stop does.

When a tire makes physical contact with the wheel well during suspension compression. Adjusting bump stop length (such as using an extended stop) restricts up-travel just enough to prevent rubbing. Used to size your front bump stops.

A front bump stop designed to exactly match the factory upward travel limits of the vehicle. This is the standard recommendation for vehicles running factory-size or slightly larger tires that do not suffer from tire rub during compression.

A slightly taller front bump stop (typically around 64mm for Toyotas) specifically designed for rigs running oversized tires (35 inches or larger). By artificially restricting upward wheel travel by a quarter-inch, these stops prevent aggressive tire rub against the wheel well during full articulation.

The absolute minimum measurement of a rear shock absorber when it is fully collapsed. Your bump stops must engage and stop upward axle movement before the shock reaches this length; otherwise, the shock internals will bear the full weight of the impact, leading to blown seals and catastrophic shock failure. Used to size your rear bump stops.

A rear bump stop designed to protect shocks that maintain the original factory compressed length. Note that even if a vehicle has a lift kit, it may still use standard travel rear shocks, making this the correct bump stop choice.

Suspension components designed to accommodate a lift kit (typically 2 inches or more) and longer shocks. Extended-length bump stops are usually required to protect extended-travel shocks from over-compressing.

A longer rear bump stop designed for vehicles utilizing aftermarket shocks with a compressed length that is 0.5 to 1 inch longer than factory specs. Brand Specificity: A core sizing option from Perry Parts, crucial for protecting vehicles with extended shocks.

The longest bump stop configuration, designed for aggressive suspension setups where the shock's compressed length is more than 1 inch longer than the OEM shock. Brand Specificity: A custom sizing option from Perry Parts tailored for highly modified rigs. Check out Perry Parts Long Travel Rear bump stops.

The process of absorbing and dissipating the kinetic energy of an impact as the suspension compresses. Proper damping smooths out the ride instead of violently stopping the axle.

A design architecture where the bump stop material becomes denser and more resistant the further it is compressed. This allows for a soft initial touch on small bumps but firm, unyielding protection against massive hits.

The speed at which a bump stop or shock absorber returns to its original shape after being compressed. Controlling rebound is crucial so the vehicle doesn't "pogo" or bounce aggressively after a hard hit.

A specialized machine used to test, measure, and tune the force, compression, and rebound characteristics of suspension components to ensure consistent, real-world performance.

A specialized, industrial 3D-printing process that bypasses standard filament and extrudes high-grade industrial polymers directly. This creates incredibly strong, durable suspension parts capable of surviving hundreds of thousands of extreme compression cycles.

Strategically designed empty ports built into the core of our bump stops. During low-speed crawling, air easily escapes the passages for a soft, compliant ride. During high-speed impacts, air pressure rapidly builds up inside the ports, actively increasing the bump stop's resistance for maximum support.