Performance
Estimate static front/rear brake bias from piston count, piston diameter, rotor size, and pad friction. Includes level-ground stopping distance from speed and tire μ using d = v²/(2μg).
Brake bias is how much total braking torque comes from the front axle vs the rear. Too much rear on a light tail can lock the rears; too little rear on a swapped heavy front hurts stopping distance. This tool estimates static bias from piston area, rotor diameter, and pad coefficient.
The stopping-distance tab uses level-ground physics: d = v²/(2μg) with tire friction μ — ideal dry pavement, not ABS modulation or downhill.
A good outcome: a bias percentage to compare against rough front/rear weight split and a baseline 60–0 distance for tire upgrades.
Use the same μ (mu) for front and rear pads unless you have dyno friction data — street pads are often similar but not identical.
Rotor diameter is measured to the effective radius where the pad sweeps, not outer hat diameter.
Proportioning valves and ABS change real-world balance — static bias is a design starting point, not a lap simulation.
Torque ∝ μ × piston area × rotor radius (relative units)
Front bias % = Front torque ÷ (Front + Rear torque)
Stop distance (ft) = (mph × 1.4667)² ÷ (2 × μ × 32.174)
Torque ∝ μ × (piston area) × (rotor radius). Bias % = front ÷ (front + rear).
Stop distance (ft) = (mph × 1.4667)² ÷ (2 × μ × 32.174). Assumes constant μ and full lock — real stops are longer.
Larger front rotors and four-piston fronts vs stock rear drums can push static bias toward 75–80% front. Compare to ~55/45 weight split at rest — you may want a proportioning valve or rear upgrade for balanced stops.
This is static hydraulic bias — ABS, proportioning valves, tire grip, and weight transfer change real-time balance. Big front kits on light rears can lock fronts instantly despite “ideal” bias on paper.
Stopping distance mode assumes constant μ and no ABS cycling — real-world stops are longer.
Often near static weight distribution as a starting point — then adjust with prop valves for track use. Front-heavy cars need more front torque, not 50/50 blindly.
Torque scales with piston area × rotor radius — larger front rotors increase front share unless rear is upgraded too.
Modern performance cars on sticky tires can hit 100–110 ft from 60 in instrumented tests; street tires and ABS are longer — use μ you can justify.
Pair this calculator with these related tools in the garage — same session, no signup.