The Most Common Reasons for a Poor Brake Pedal:
- The bleeder screws on the calipers are not facing up.
- The master cylinder was not bench bled or was not bled completely.
- Defective rebuilt master cylinder with pitted cylinder bore or defective pressure seals.
- Master cylinder bore size too small for the system volume requirements.
- Use of a disc/drum master for a 4 wheel disc system.
- Master cylinder lower than the calipers or wheel cylinders.
- Lines or components near a heat source.
- Lines that loop up higher than the master cylinder and then come back down. Will trap air.
- Low drag metric calipers without the use of a quick take up master cylinder.
- No residual valve to rear drum brakes.
- Drum brake wheel cylinders too large.
- Silicone brake fluid. It can tend to trap air and cause seals to swell. In addition, if Dot 5 is used and it comes in contact with Dot 3/4, it can become a sludged up mess!
- Rear caliper parking
brake / pistonsnot set properly with a rear disc system.
- Rear calipers not being bled properly. Most brake problems with four wheel disc cars
comesfrom the rear.
- Improper pedal adjustment with too much free play.
- Old or inferior quality brake hoses.