Wilwood Adjustable Proportioning Valve
WIL260-8419
The Wilwood Adjustable Brake Proportioning Valve gives builders precise control over rear brake pressure for custom, racing, and high-performance brake systems. This compact valve provides smooth, repeatable adjustment from full system pressure to a maximum 57% pressure reduction, allowing brake bias to be tuned for changing vehicle weight distribution, tire size, and braking conditions.
Its forged billet aluminum body offers greater strength and rigidity than conventional machined valves while reducing overall size and weight. Compatible with both disc and drum brake systems, this valve simplifies rear brake tuning on hot rods, rock crawlers, Ultra4 cars, drag cars, road race vehicles, and custom chassis.
Includes:
- (1) Wilwood Adjustable Brake Proportioning Valve
- (2) 1/8"-27 NPT to 3/8"-24 Inverted Flare Female Brake Line Adapters
Specifications
| Specification | Details |
|---|---|
| Manufacturer | Wilwood |
| Product Type | Adjustable Brake Proportioning Valve |
| Adjustment Range | 0–57% Pressure Reduction |
| Operating Pressure | Approximately 100–1,000+ PSI |
| Body Material | Forged Billet Aluminum |
| Internal Components | Steel |
| Finish | Clear Anodized |
| Weight | 5.2 oz |
| Inlet Port | 1/8"-27 NPT |
| Outlet Port | 1/8"-27 NPT |
| Mounting Holes | (2) × 0.25" |
| Mounting Hole Spacing | 1.00" Center-to-Center |
Fitment
| Fitment Requirement | Compatibility |
|---|---|
| Brake Systems | Disc / Disc and Disc / Drum Systems |
| Brake Line Size | 3/16" Hard Line (Using Included Adapters) |
| Brake Circuit | Typically Installed in Rear Brake Circuit |
| Vehicle Types | Street, Off-Road, Drag Racing, Dirt Track, Road Race, and Custom Vehicles |
Fitment Notes
- Compatible with both disc/drum and disc/disc hydraulic brake systems.
- Normally installed in the rear brake circuit to fine-tune rear brake pressure.
- Compact housing allows installation in exposed or concealed mounting locations.
- Works with standard 3/16" brake tubing using the included 3/8"-24 inverted flare adapters.
- Not intended to replace a combination valve or residual pressure valve where those components are required.
- Always bleed the brake system thoroughly after installation and verify proper brake balance in a controlled environment before normal vehicle operation.
FAQ
1. What does a proportioning valve do?
A proportioning valve limits hydraulic pressure to the rear brakes once a preset pressure threshold is reached. This helps prevent premature rear wheel lockup while allowing the front brakes to continue generating maximum stopping force.
2. Why would a custom vehicle need an adjustable proportioning valve?
Changes such as larger brake kits, different caliper piston sizes, altered vehicle weight distribution, larger tires, suspension modifications, or engine swaps often change brake balance. An adjustable valve allows the rear brake pressure to be tuned for the new combination.
3. What advantages does the forged billet body provide?
The forged manufacturing process aligns the aluminum grain structure, creating a stronger and more rigid housing than a conventionally machined block. This allows the valve to withstand high brake pressures while remaining compact and lightweight.
4. How is the valve adjusted?
The adjustment knob uses a fine-thread mechanism for smooth, infinitely variable control. Turning the knob fully clockwise provides full system pressure, while rotating it counterclockwise progressively reduces rear brake pressure up to approximately 57%.
5. Where should a proportioning valve be installed?
Most adjustable proportioning valves are installed in the rear brake circuit after the master cylinder. The ideal setting should be established through careful brake testing so the front brakes reach their traction limit slightly before the rear brakes under maximum braking.
