Having a hard brake pedal can make it difficult to slow down or stop your vehicle, making it feel like you're standing on the pedal. A stiff brake pedal is a severe safety problem that should be fixed immediately since it makes it more difficult to slow down your vehicle. What causes the brake pedal to be stiff? Stiff braking is usually caused by an issue with the brake booster. Brake boosters increase the amount of force you can apply to your brake pedal, and they work in conjunction with the hydraulic fluid in the lines. A diaphragm separates the two chambers of a typical vacuum brake booster, which is situated between the master cylinder and the brake pedal. A low-pressure vacuum is created in the front chamber by removing air. Pressing the brake pedal in the back chamber allows air to enter. The air chamber's higher pressure forces the diaphragm and push rod toward the low-pressure side. The master cylinder's power-assisted push rod makes it easy to move. The master ... read more