Fault Diagnosis — Brake System (Opel Ascona C)

Before attempting to diagnose a fault using the following table, check that any braking problems are not caused by:

• Uneven or incorrect tire pressure.
• Wear of the steering mechanism.
• Defects in the suspension and shock absorbers.
• Incorrect positioning of the body.

Symptom / Cause /s/.

• The pedal travels a long distance before the brakes are applied.
• Incorrect remote control rod/servo push rod adjustment.
• The brake shoes are positioned too far from the drums (manual adjustment).
• The self-adjusting mechanism is faulty (if there is one).
• The linings are badly worn.
• The brake disc is too worn.

Poor braking despite the pedal being firm.

• The pads, discs or drums are badly worn or scratched.
• One or more hydraulic cylinders have seized up, causing some brake shoes to not press against the drums (or pads on the disc).
• Brake linings are contaminated with oil.
• The wrong type of pads are installed (too hard).
• The brake shoes are assembled incorrectly.
• The servo unit is not functioning.

The car swerves to the side after braking.

• Brake pads or linings are contaminated with oil on one side.
• The hydraulic cylinder on one side is partially or completely stuck.
• Various lining materials are installed between the sides.
• Brake discs are not all the same.
• Uneven wear between sides caused by partially seized cylinders.

When braking, the pedal feels like a "sponge".

• There is air in the hydraulic system.

When braking, the pedal feels like a "spring".

• The brake pads have not rubbed against the drums
• (after installing new ones).
• The master cylinder or rear brake plate mounting bolts are not tightened properly.
• Severe wear of the brake drums when applying the brakes causes warping.
• Inaccurately installed disks.

The pedal goes all the way down with little or no resistance and the brakes barely work.

• A leak in the hydraulic system resulting in insufficient pressure to operate the cylinders.
• If there are no signs of leakage, then the internal seals are not maintaining pressure.

Seizure, vibration, overheating.

• One or a combination of several of the above reasons.
• The shoes are not installed correctly in relation to the leading and trailing ends.
• The shoe return spring is broken.
• Excessive disc wear.
• The drum is warped.
• Incorrect remote control rod/servo push rod adjustment.

Insufficient operation of the servo unit.

• The vacuum hose is disconnected or leaking.
• The check valve is faulty or incorrectly installed.
• Internal failure of the servo unit.

Material was taken from a resource [opelbook.ru]