Electronic brake force distribution automatically varies the braking force between front and rear wheels based on vehicle loading and deceleration. This system ensures optimal braking performance regardless of whether the car is lightly loaded or carrying maximum weight. ## How EBD Works When you apply the brakes, weight transfers forward, increasing the load on the front wheels and reducing load on the rear. The ideal brake force distribution matches the available grip at each axle. Front wheels can handle more braking force because they carry more weight during deceleration. Traditional brake proportioning valves mechanically limited rear brake pressure based on the assumption of a typical vehicle loading. EBD replaces this mechanical valve with electronic control based on actual wheel load measurements. The EBD system continuously monitors the load on each wheel through the wheel speed sensors and suspension position sensors. When it detects that the rear wheels are carrying less load, it reduces brake pressure to the rear. This prevents the rear wheels from locking before the front, which would cause instability. It also ensures the maximum possible braking force is applied across all wheels simultaneously, minimising stopping distances. ## EBD and ABS Interaction EBD works closely with ABS to provide the best possible braking in all conditions. Under normal braking, EBD optimises the front-rear balance. When a wheel is about to lock, ABS takes over that wheel's brake pressure independently. ABS can also override EBD decisions if individual wheel slip is detected. Even if EBD is directing more pressure to the front, ABS will reduce pressure at any wheel that threatens to lock, regardless of the overall distribution. The systems share the same hydraulic hardware and control module. EBD functionality is typically integrated into the ABS module rather than being a separate system. The distinction between EBD and ABS is largely one of software function rather than separate hardware. Without EBD, vehicles with heavy loads in the rear may lock rear wheels first, causing the rear to swing around. Vehicles with light rear loads may not use all available front grip, extending stopping distances. ## Load Sensing and Rear Brake Proportioning Some vehicles use mechanical load-sensing valves that adjust rear brake pressure based on suspension compression. This gives rough adjustment for vehicle loading without requiring electronic sensors. More sophisticated electronic systems use actual weight sensors or estimate load from suspension deflection measurements. This allows precise adjustment for any loading condition, from an empty vehicle to one carrying maximum payload. The rear brake proportioning can vary between left and right wheels on vehicles with more advanced systems, providing additional stability control through asymmetric braking. ## Frequently Asked Questions **Is EBD part of the MOT test?** EBD is tested as part of the ABS inspection during MOT. The tester applies the brakes firmly and checks that the ABS activates on at least one wheel. Any stored fault codes related to ABS or EBD will cause the test to fail. **Does EBD affect braking feel?** EBD is completely transparent to the driver. The driver applies brakes normally and EBD optimises the distribution without any change in pedal feel or braking response. **Can I feel EBD working?** Under normal conditions, EBD cannot be felt. The adjustment happens so smoothly that drivers are unaware of its operation. Only under extreme conditions with very heavy loads might the rear brake pressure increase noticeably when load transfers forward.