Radflo 2.5 Hydraulic Bump Stop - 2", 3" & 4" Travel
6SB-001-00
The Radflo 2.5 Hydraulic Bump Stop provides progressive bottom-out control for heavy vehicles and high-impact off-road suspension systems. Acting as a secondary shock absorber during the final inches of suspension compression, its velocity-sensitive damping increases resistance during severe impacts to help reduce harsh bottoming and stress on the chassis, shocks, suspension mounts, and occupants. The heavy-duty 2.5" body and 1.625" chrome-plated alloy steel shaft make it a strong choice for rock crawlers, Ultra4 race cars, desert trucks, and custom off-road buggies.
Available with 2", 3", or 4" of travel, the Radflo 2.5 bump stop features a Freeflo Racing Piston, CNC-machined bronze rod guide, and rebuildable sealing system engineered for demanding suspension loads. Its nitrogen-charged, velocity-sensitive valving provides controlled compression during hard landings and extreme suspension movement. Each unit is fully serviceable and tunable, allowing builders to match bump stop performance to vehicle weight, suspension geometry, and intended terrain.
Includes:
- (1) Radflo 2.5 Hydraulic Bump Stop – Selected Travel Length
- Universal Spherical Bearing
- Mounting Hardware
Note: Sold individually. Bump pads, bump cans, and bump can mounting hardware are sold separately. Select the correct travel length before ordering.
Specifications
| Manufacturer | Radflo Suspension Technology |
|---|---|
| Product Type | Off-Road Hydraulic Bump Stop |
| Mounting Style | Pin Mount with Spherical Bearing |
| Body Diameter | 2.5" |
| Available Travel Lengths | 2", 3" & 4" |
| Shaft Diameter | 1.625" (1-5/8") |
| Shaft Material | Mirror-Polished Alloy Steel |
| Shaft Finish | Chrome Plated |
| Body Material | SSID Alloy Steel Tube |
| Body Finish | Clear Cadmium Plated |
| Body Caps / Eyelets | CNC-Machined 6061 Aluminum |
| Body Cap Finish | Black Anodized |
| Rod Guide | CNC-Machined Bronze with PTFE Coating |
| Piston | Radflo Aluminum Freeflo Racing Piston |
| Seal Design | Rebuildable Quad-Ring & Lip Seal Combination |
| Valving Type | Velocity-Sensitive Deflective Disc |
| Valving Adjustment | Self-Adjusting / Velocity-Sensitive |
| Valving Tuning | Consumer or Factory Tunable |
| Suspension Fluid | Radflo High-Temperature Foam-Resistant Fluid |
| Pressurization | Nitrogen Gas |
| Published Nitrogen Pressure | 200 PSI |
| Serviceability | Consumer or Factory Serviceable |
| Primary Application | Heavy-Duty Off-Road Suspension Bottom-Out Control & Impact Absorption |
| Quantity | (1) Bump Stop / Sold Individually |
Available Travel Configurations
| Part Number | Travel Length | Body Diameter | Shaft Diameter |
|---|---|---|---|
| 6SB-001-00 | 2" | 2.5" | 1.625" |
| 6SB-002-00 | 3" | 2.5" | 1.625" |
| 6SB-003-00 | 4" | 2.5" | 1.625" |
Travel Selection: Shorter travel options are easier to package in compact suspension layouts, while longer travel options provide additional damping stroke when properly positioned. Select travel based on suspension geometry, vehicle weight, available clearance, and intended bump stop engagement.
Nitrogen Note: Radflo lists 200 PSI in the supplied specifications. Confirm the correct service pressure and tuning requirements for your specific application before charging or adjusting the bump stop.
Fitment
Universal Fitment for Custom Off-Road Suspension Systems
Designed for heavy-duty suspension applications requiring a pin-mounted hydraulic bump stop with compatible spherical bearing mounting hardware.
Common Applications:
- Rock Crawlers & Rock Bouncers
- Ultra4 Race Cars
- Desert Racing Trucks & Prerunners
- Custom Tube-Chassis Buggies
- Heavy-Duty Trail Rigs
- Long-Travel Off-Road Suspension Systems
- High-Impact Competition Vehicles
Fitment & Installation Notes:
- Uses a pin-mount configuration with spherical bearing and mounting hardware.
- Available in 2", 3", and 4" travel configurations.
- Verify mounting dimensions and available suspension clearance before ordering.
- Select travel length based on suspension geometry, chassis packaging, and desired engagement point.
- Mock up bump stop mounting and strike pad placement before final fabrication.
- Cycle suspension through full compression to verify bump stop alignment and available clearance.
- Position the bump stop to contact a flat, reinforced strike pad without excessive side loading.
- Confirm the bump stop engages before the primary shock or suspension reaches its mechanical limit.
- Check clearance around axle housings, tires, shocks, steering components, and suspension links.
- Final valving and nitrogen pressure tuning may be required for vehicle weight, suspension leverage, and intended terrain.
- Professional installation and suspension tuning are recommended.
Builder Note: The larger 2.5" hydraulic bump stop is a practical option for heavier off-road vehicles and suspension systems exposed to repeated high-energy impacts. Proper engagement height and strike pad alignment should be established during suspension mockup with the axle, shocks, links, and tires installed. Confirm that the bump stop provides sufficient damping travel without becoming the suspension's unintended mechanical limit.
FAQ
What does a Radflo hydraulic bump stop do?
A hydraulic bump stop acts as a secondary shock absorber during the final portion of suspension compression. It progressively slows suspension movement and absorbs impact energy, helping reduce harsh bottoming and stress on the chassis, suspension components, and occupants.
What is the difference between Radflo 2.0 and 2.5 hydraulic bump stops?
The Radflo 2.5 features a larger 2.5" body and 1.625" shaft compared to the 2.0 model's 2.0" body and 1.25" shaft. The larger construction is suited to heavier vehicles and demanding high-impact suspension applications. The 2.5 model uses a pin-mount configuration with spherical bearing hardware, while the 2.0 model uses a pinch-mount design.
How do I choose between 2", 3", and 4" travel?
Travel selection depends on available mounting space, suspension geometry, vehicle weight, and desired engagement point. Shorter travel options package more easily, while longer travel options provide additional damping stroke and can begin controlling suspension movement earlier when properly positioned.
What is velocity-sensitive damping?
Velocity-sensitive damping increases resistance as the bump stop shaft compresses faster. Slow suspension movement produces less damping force, while hard landings and severe impacts generate greater resistance to help control bottom-out.
Why does the Radflo 2.5 use a 1.625" shaft?
The large-diameter chrome-plated alloy steel shaft provides strength and resistance to bending under repeated high-impact loads. Its mirror-polished surface and PTFE-coated bronze rod guide help reduce friction and support smooth operation.
What is the Radflo Freeflo Racing Piston?
The Radflo Freeflo Racing Piston is an aluminum piston designed to control hydraulic fluid movement through the bump stop. Combined with velocity-sensitive deflective disc valving, it provides controlled compression resistance during suspension impacts.
Can Radflo 2.5 hydraulic bump stops be rebuilt and tuned?
Yes. Radflo 2.5 hydraulic bump stops are designed to be serviceable and tunable. Internal valving can be adjusted to suit different vehicle weights, suspension designs, terrain, and driving conditions.
What nitrogen pressure does the Radflo 2.5 bump stop use?
The supplied Radflo specifications list 200 PSI nitrogen pressure. Confirm the appropriate service pressure and charging procedure for the specific bump stop before making adjustments. Use dry nitrogen and suitable high-pressure charging equipment.
Does the Radflo 2.5 bump stop include mounting hardware?
Yes. The supplied product specifications list a universal spherical bearing and mounting hardware. Custom vehicle mounting brackets and reinforced strike pads are separate components.
When should a hydraulic bump stop engage?
The bump stop should engage during the final portion of suspension compression and before the primary shock, coilover, or other suspension components reach their mechanical limits. Proper engagement height helps protect the suspension without unnecessarily restricting usable travel.
