PdV Motorsports METRIC Brake System Calculator

Brake Calculator

About This Calculator
This brake calculator, originally developed by Jake Latham, has been enhanced with advanced features inspired by Brake Design and Safety by Rudolf Limpert. It is designed to help enthusiasts and engineers determine critical brake system parameters under threshold braking (maximum braking force without wheel lockup), suitable for both custom motorsport setups and OEM vehicles with power-assisted brakes.

Key Features
- Calculates dynamic weight transfer, brake torque, and front/rear bias for precise system design.
- Includes advanced metrics such as brake bias ratio, hydraulic pressure ratio, braking efficiency, fluid volume displaced, and master cylinder stroke checks.
- Supports OEM vehicles with a brake booster assist ratio input, enabling more accurate modeling of power-assisted systems.
- Features a balance bar adjustment for fine-tuning front/rear brake force distribution.

Default Values
Default values are what they are. You must verify your vehicle's specifications (e.g., weights, rotor diameters, pedal/booster ratio) using manufacturer data or measurement tools for best results.

Feedback and Future Updates
I plan to expand the calculator with additional features inspired by *Brake Design and Safety*. Have suggestions for improvements? Contact us at pdvmotorsports@gmail.com to share your ideas.

Step 1: Vehicle Information

kg
kg
kg
kg
mm
mm
mm
mm
G
Results:
1859 kg
52.77 %
2624 N
11578 N
6655 N
63.50 %
Note: This calculator assumes fixed calipers. Enter piston diameters for one side of one fixed caliper (inboard or outboard). Piston areas are doubled to account for both sides of a caliper and quadrupled for the entire axle (two calipers).
N
:1
:1
mm
Front Brakes
mm
mm
mm
Rear Brakes
mm
mm
mm
Front (Per Side)
mm
mm
mm
Rear (Per Side)
mm
mm
mm
Assumes fixed calipers with matching piston sets on each side. Piston areas are calculated per side, doubled for each caliper, and quadrupled for each axle (two calipers).
0.000 mm²
0.000 mm²
0.000 mm²
0.000 mm²
0.000 mm²
0.000 mm²

Line Pressures and Balance Bar

Balance Bar Controls
mm
50.0%
50.0%
38 mm
38 mm
Slide to adjust brake bias. Total distance defines the balance bar length.
Resultant Pressures and Torques Per Rotor
0.0 MPa
0.00 Nm
0.0 MPa
0.00 Nm
cc/MPa
MPa
MPa
mm
Front Brakes
mm
mm
mm
Rear Brakes
mm
mm
mm
Front (Per Side)
mm
mm
mm
Rear (Per Side)
mm
mm
mm
Assumes fixed calipers with matching piston sets on each side. Piston areas are calculated per side, doubled for each caliper, and quadrupled for each axle (two calipers).
0.000 mm²
0.000 mm²
0.000 mm²
0.000 mm²
0.000 mm²
0.000 mm²

Line Pressures and Balance Bar

Balance Bar Controls
mm
50.0%
50.0%
38 mm
38 mm
Slide to adjust brake bias. Total distance defines the balance bar length.
Resultant Pressures and Torques Per Rotor
0.0 MPa
0.00 Nm
0.0 MPa
0.00 Nm
cc/MPa
MPa
MPa
Required Baseline Upgrade Delta
Front Axle Torque (Nm)
0.99 0.00 0.00 0%
Rear Axle Torque (Nm)
0.99 0.00 0.00 0%
Total Brake Torque (Nm)
1.98 0.00 0.00 0%
Front Bias (%)
99.00 0.00 0.00 0%
Rear Bias (%)
1.00 0.00 0.00 0%
Hydraulic Pressure Ratio
- 0.00 0.00 0%
Braking Efficiency (Nm/N)
- 0.00 0.00 0%
Braking Power (kW)
- 0.00 0.00 0%
Pedal Feel Stiffness (unitless)
- 0.00 0.00 0%
Note: Achieved values are calculated based on the current hydraulic setup, balance bar adjustment, and brake booster assist ratio. You can have too much torque for a safe system in emergency situations. Use your brain.
Status Indicators: Are for reference only. Green checks appear when achieved torque is >= 98% of required torque and ±5% of required bias.
Front/Rear Bias: Percentage of total torque distributed to front and rear axles.
Hydraulic Pressure Ratio: Ratio of front to rear line pressures (front/rear), showing pressure balance impact on performance.
Braking Efficiency: Total torque per unit of leg force (Nm/N); typical fixed caliper systems range from 40–60 Nm/N.
Braking Power: Kilowatts absorbed by brakes at max G and 100km/h (per Eq. 3-6 in Brake Design and Safety).
Pedal Feel Stiffness: Arbitrary measure of pedal firmness; ratio of pedal leverage to hydraulic gain (higher = firmer pedal).
Brake Booster Assist Ratio: Amplifies pedal force; set to 1 for manual brakes or calculate for boosted systems (e.g., 3.667 for typical vacuum boosters).
Required Baseline Upgrade Delta
Front Fluid Volume Displaced (cc)
- 0.000 0.000 0%
Rear Fluid Volume Displaced (cc)
- 0.000 0.000 0%
Front Master Movement (mm)
- 0.000 0.000 0%
Rear Master Movement (mm)
- 0.000 0.000 0%
Front Stroke Check
- Safe Safe -
Rear Stroke Check
- Safe Safe -
Pedal Displacement (mm)
- 0.000 0.000 0%
Fluid volumes and master movements are calculated for the entire axle (two calipers, both sides). Stroke checks indicate if the master cylinder stroke is sufficient. Fluid volume calculations use a fixed compression factor and do not account for temperature effects for simplicity (per Limpert Ch. 3).