Adjustable Brake Bias Proportioning Valve

Hose Adapters

£44.09

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Adjustable Brake Bias Proportioning Valve

This Adjustable Brake Bias Proportioning Valve provides manual control over hydraulic pressure to the rear brake circuit, allowing front-to-rear brake balance to be fine-tuned to suit the vehicle, brake setup and driving conditions.

Continuous Brake Bias Adjustment

The adjustment knob provides continuous fine control without fixed click positions. Turning the knob counter-clockwise progressively reduces pressure to the rear brake circuit, with approximately 60% maximum pressure reduction at the fully counter-clockwise setting.

Rear Brake Circuit Installation

The valve is typically installed between the master cylinder and rear brake line t-piece. It can only reduce hydraulic pressure downstream of the valve and cannot increase pressure above that supplied by the braking system.

1/8"-27 NPT Connections

The valve has 1/8"-27 NPT female inlet and outlet ports, with selectable brake hose adapters for integration into compatible 3/8"-24 UNF brake lines.

Selectable Brake Hose Adapters

Choose brass adapters for 3/8"-24 UNF male concave fittings or stainless steel adapters for 3/8"-24 UNF female concave fittings.

Black Anodised Aluminium Construction

Manufactured from 6061-T6 aluminium with a black anodised finish for a lightweight, durable and corrosion-resistant construction.

Optional Mounting Cage

A dedicated Brake Bias Valve Mounting Cage is available separately for a secure, tidy installation.

Brake Bias Valve: 1 x Adjustable Brake Bias Proportioning Valve 1/8"-27 NPT female inlet and outlet connections
Brake Hose Adapters: 2 x Selected Adapters Brass for male concave fittings or stainless steel for female concave fittings

Type: Adjustable Brake Proportioning Valve Reduces hydraulic pressure downstream of the valve
Material: 6061-T6 Aluminium Lightweight, high-strength alloy
Finish: Black Anodised Protects against wear and corrosion

Inlet: 1/8"-27 NPT Female Tapered thread · Use suitable thread sealant
Outlet: 1/8"-27 NPT Female Tapered thread · Use suitable thread sealant

Connect the IN port from the master cylinder circuit and the OUT port towards the rear brakes.

Typical Installation: Rear Brake Circuit Typically installed between the master cylinder and rear brake line t-piece
Adjustment Type: Continuous Knob Adjustment Fine adjustment without fixed click positions
Minimum Pressure Reduction: Fully Clockwise Closest setting to having no proportioning valve in the circuit
Adjustment Direction: Counter-Clockwise to Reduce Pressure Progressively reduces rear brake pressure
Maximum Pressure Reduction: Approximately 60% Fully counter-clockwise

The valve can only reduce downstream pressure; it cannot increase pressure above that supplied by the braking system.

Starting point: count the total turns from fully clockwise to fully counter-clockwise, then return the knob halfway to begin fine-tuning.

Available brake hose adapter configurations
Selection	Brake Hose Connection
2 x Brass Adapters	For 3/8"-24 UNF Male Concave Fittings Standard adapter configuration
2 x Stainless Steel Adapters	For 3/8"-24 UNF Female Concave Fittings Optional adapter configuration

Both adapter options install into the valve's 1/8"-27 NPT female inlet and outlet ports.

Mounting Holes: 2 x M6 For secure mounting
Installation Position: Accessible Location Allows adjustment after installation
Flow Direction: IN → OUT Follow the marked valve direction

Bleed the brake system thoroughly after installation and check all connections for leaks.

Track & Competition Cars
ABS Deletes
Brake Conversions
Big Brake Kits
Motorsport Brake Systems
Modified Brake Systems

Brake Fluid

Bias Valve Mounting Cage

Purpose-built cage for a secure, tidy installation.

Free repair or replacement for two years from the date of purchase. Learn more

Frequently Asked Questions

What does a brake bias proportioning valve do?
It reduces hydraulic pressure to the rear brake circuit, allowing the front-to-rear brake balance to be adjusted.
How is the brake bias adjusted?
The knob provides continuous adjustment without fixed click positions. Turning it counter-clockwise progressively reduces rear brake pressure.
How much can the valve reduce rear brake pressure?
At the fully counter-clockwise setting, the valve provides approximately 60% maximum pressure reduction. Fully clockwise gives the minimum reduction.
Where should the brake bias valve be installed?
It is typically installed in the rear brake circuit between the master cylinder and rear brake line t-piece.
Which connections are on the valve?
The valve has 1/8"-27 NPT female inlet and outlet ports. Use suitable thread sealant on the tapered NPT connections.
Which brake hose adapters are available?
Choose brass adapters for 3/8"-24 UNF male concave fittings or stainless steel adapters for 3/8"-24 UNF female concave fittings.
Can the valve increase rear brake pressure?
No. The valve can only reduce hydraulic pressure downstream; it cannot increase pressure above that supplied by the braking system.
What is a good starting point when setting the valve?
Count the total turns from fully clockwise to fully counter-clockwise, then return the knob halfway before beginning fine adjustment.
Is a mounting solution available?
Yes. A dedicated Brake Bias Valve Mounting Cage is available separately.