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Adjustable Air Spring Rate for Off-Road Suspension
This FOX air shock uses an adjustable nitrogen charge to tune spring rate for universal off-road motorsport suspension use. The 981-25-051 configuration combines its documented body size, travel, shaft diameter, and valving for competition and trail applications.
Key Features
- 981-25-051 is a Factory Series air shock with a 2.5 inches body and 12 inches of travel
- The 1-5/8 inches shaft supports the documented configuration
- Normal valving is 40/80
- Nitrogen charge pressure provides spring rate adjustment
- The black finish identifies this configuration
- Universal application requires compatible mounts, geometry, and suspension travel
Fitment
| Years | Make | Model | Position | Restriction |
|---|---|---|---|---|
| Universal application | Off-road | Motorsport suspension | Universal | Not vehicle-specific |
Specifications
| Detail | Value |
|---|---|
| Body Diameter | 2.5 inches |
| Travel | 12 inches |
| Shaft Diameter | 1-5/8 inches |
| Normal Valving | 40/80 |
| Finish | Black |
| Spring Adjustment | Nitrogen charge pressure |
| Product Type | Air shock |
| Package Quantity | One shock |
What's Included
- One Factory Series air shock
About FOX
FOX develops suspension products for off-road, motorsport, and performance applications. Its air shocks use nitrogen pressure and application-specific damping configurations to give builders a tunable suspension component.
FAQ
What is the 981-25-051?It is a FOX Factory Series air shock in the configuration listed in the specifications.
Is this shock vehicle-specific?No. It is a universal off-road component, so the builder must confirm mounting dimensions, motion ratio, clearance, and travel for the intended vehicle.
How is spring rate adjusted?Spring rate is adjusted by changing nitrogen charge pressure with suitable service equipment and the correct setup procedure.
How much travel does this shock have?The documented travel is 12 inches.
What shaft size is used?The shaft diameter is 1-5/8 inches.
What valving does it use?The normal valving configuration is 40/80.
What is included?The package contains one air shock. Verify any vehicle-specific mounting hardware separately before installation.
What should be checked before installation?Confirm mounts, clearances, suspension travel, motion ratio, nitrogen service requirements, and the intended damping setup before fitting the shock.
Installation Instructions
- Confirm the shock dimensions and universal application match the planned suspension geometry.
- Measure available mounting space, ride height, compression clearance, and extension clearance.
- Secure the vehicle or chassis and remove the existing component according to the vehicle service procedure.
- Install compatible mounts and position the shock without side loading the shaft.
- Check that the shock moves through the full suspension range without contact or binding.
- Set an initial nitrogen pressure and damping setup using the applicable FOX service guidance.
- Torque mounting hardware to the vehicle or mount manufacturer's specification.
- Cycle the suspension again, inspect all clearances, and confirm the setup before normal use.
FOX
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