Description
AP Racing Brake Bias Valve – CP3550 / CP4550 Series
Introduction
The AP Racing Brake Bias Valves are high-precision proportioning valves designed for motorsport applications, allowing accurate adjustment of rear brake pressure to achieve optimal front/rear balance under varying track and grip conditions.
Description
The CP3550-13 model features seven discrete adjustment positions, allowing the driver or co-driver to select the most suitable brake ratio quickly and consistently. The CP4550-1 version is a Twin Bore design, managing two separate hydraulic circuits simultaneously — ideal for dual master cylinder setups.
Both valves progressively reduce rear circuit pressure to prevent wheel lock-up and maintain stability during deceleration. Manufactured from high-grade aluminium alloy, they provide low hysteresis, repeatable operation, and a compact, lightweight design.
Technical Data
AP Racing CP3550-13 (Single Bore):
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Adjustment positions: 7
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Threads: M10x1 (inlet/outlet)
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Nominal ratio: 0.325
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Output pressure (at 100 bar input):
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Pos. 1: 38.0 – 41.5 bar
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Pos. 2: 44.0 – 47.5 bar
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Pos. 3: 50.0 – 52.5 bar
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Pos. 4: 55.0 – 57.5 bar
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Pos. 5: 60.0 – 63.5 bar
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Pos. 6: 65.5 – 69.5 bar
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Pos. 7: 73.0 – 76.5 bar
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Max. operating pressure: 100 bar
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Weight: approx. 180 g
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Dimensions: 105 × 69 × 31 mm
AP Racing CP4550-1 (Twin Bore):
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Adjustment positions: 7
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Ports: 2 × inlet, 2 × outlet (M10x1)
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Type: Twin Bore dual-circuit
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Max. operating pressure: 100 bar
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Weight: approx. 230 g
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Dimensions: 137 × 82 × 34 mm
Applications
The AP Racing Proportioning Valves are used across Formula, GT, touring, and rally cars to fine-tune rear brake pressure balance. The stepped design provides reliable, repeatable bias settings, while the Twin Bore model offers dual-circuit control for advanced braking systems.