If you notice that the brakes feel softer or harder than usual when driving, it's essential to check several aspects.
Firstly, inspect the positions of the four wheels to see if any brake caliper or oil pipe is leaking. This is the most common cause of soft brakes and is often associated with drum brake models, where brake calipers are prone to oil leaks due to design and quality issues. The brake fluid leakage leads to a decrease in braking pressure, resulting in soft brakes, which can only be resolved by replacement during maintenance.
Likewise, if the brakes feel particularly hard when pressed, it's likely due to a faulty brake caliper. Rusting of the pistons inside the brake caliper can cause them to seize, resulting in increased resistance or even immobility. This condition is often referred to as "brake lock-up." It's crucial to address this issue promptly as severe locking can lead to dangerous situations such as overheating of the brake pads and fluid, causing brake failure. If the brake caliper piston is severely rusted, it's advisable to replace it rather than attempting repairs.
The most common cause of hard brakes in cars is often attributed to the two positioning pins on the rear side of the brake caliper, which are prone to rusting and seizing. In such cases, cleaning and maintaining these positioning pins on all four wheels can usually resolve the issue.
Another scenario to consider is when only one of the positioning pins on the brake caliper is rusted, while the other remains functional. Over time, this imbalance can lead to uneven wear on the brake pads, resulting in soft brakes. Therefore, it's essential to check for this condition as well.
The second most common cause of hard or soft brakes is related to the brake master cylinder and the brake booster. A malfunctioning check valve on the brake booster, in particular, can disrupt the vacuum supply, rendering the brake pedal hard to press. Additionally, any cracks or leaks in the hose connecting to the engine's intake manifold can also affect brake assistance, causing a stiff pedal. However, identifying minor leaks in the brake booster hose might require thorough inspection.
Although brake booster failures are relatively rare due to their simple structure, they should not be disregarded entirely. When encountering hard brakes, it's crucial not to rush into replacing the booster without ruling out other potential causes.
In cases of soft brakes, attention should be directed towards the brake master cylinder adjacent to the brake booster. The probability of oil leakage and pressure loss from the master cylinder is significant. However, assessing this issue externally can be challenging since the cylinder's sealing side is located within the booster. A telltale sign of master cylinder malfunction is a gradual sinking of the brake pedal after multiple presses, even without visible oil leakage. In such instances, replacing the master cylinder is necessary to rectify the soft brake problem.
Furthermore, master cylinder pressure loss and oil leakage can introduce air into the brake lines. Therefore, during repairs, it's essential to purge the air from the lines; otherwise, even after master cylinder replacement, soft brake issues may persist. Some cars may exhibit a phenomenon where the brakes feel soft on the first press but return to normalcy on subsequent presses. This is often due to air trapped within the brake lines, which compresses and causes the observed fault. Bleeding the brake lines can effectively resolve this issue.
