1. Master cylinder reservoir low on fluid.
2. Brake system contains air bubbles.
3. Master or wheel cylinder piston worn or parts damaged.
4. Brake pads contaminated with grease or oil.
5. Brake pads badly worn.
6. Brake disc badly worn or warped.
7. Brake drags -brake pedal and master cylinder piston not returning completely.
8. Brake fades due to heat build up - brake pads dragging or excessive braking.