How to Tell If Your Trailer’s Brakes Are Failing

A failing brake system can compromise control, reduce stopping power, and put lives at risk. Here’s how to identify the early warning signs of brake failure before disaster strikes.

Sudden Pulling or Uneven Braking

If your trailer pulls to one side during braking, it’s time to raise a red flag. This typically indicates uneven brake shoe wear or a malfunctioning service chamber. In drum brake systems—standard on most heavy-duty trailers—air pressure moves a diaphragm in the service chamber, which activates the pushrod, slack adjuster, and S-cam. Any inconsistency in this chain can result in unbalanced brake force, leading the trailer to veer unexpectedly.

Unusual Noises: Grinding, Squealing, or Hissing

When you start hearing squealing, grinding, or metal-on-metal noises, your brakes are crying out for help. Squealing may indicate glazed brake shoes, while grinding often means the brake shoes are worn down completely, causing direct metal contact with the brake drum.

A hissing sound, however, is specific to air brake systems. This usually points to an air leak in the lines, service chamber, or valves—potentially leading to complete brake failure if left unchecked.

Increased Stopping Distance

Your trailer should come to a stop within a predictable distance. If it's taking noticeably longer, you might be looking at low air pressure, worn brake shoes, or even a malfunctioning slack adjuster. Remember, the slack adjuster compensates for wear on the shoes. If it fails to take up slack, your pushrod must travel further to engage the brakes—decreasing responsiveness and increasing stopping distance.

Low or Fluctuating Air Pressure

Air brakes rely on pressurized air stored in air tanks fed by an air compressor. When this system is compromised, your trailer’s brakes won’t have the air pressure needed for effective operation. Constant fluctuations or the inability to maintain pressure are clear indicators of:

• Leaks in air lines
• A faulty air dryer allowing moisture buildup
• A weakening air compressor

Moisture in the system can freeze in cold temperatures, restricting airflow and increasing the likelihood of brake lockup or failure.

Brake Fade During Repeated Use

"Brake fade" occurs when braking becomes progressively less effective with repeated use. This is often caused by excessive heat, which reduces the friction between the brake shoes and drum. Over time, this heat can cause the brake linings to harden or glaze over, severely compromising their grip.

Common scenarios where this occurs include:

• Steep downhill grades
• Stop-and-go urban driving
• Overloaded trailers

Regular inspection of the brake shoes and drums for glazing or cracking is crucial.

Visible Damage or Excessive Wear on Brake Components

Visual inspections are vital in any preventive maintenance program. Look out for:

• Cracked or scorched brake drums
• Worn or broken return springs
• Loose or seized slack adjusters
• Pushrods extending beyond their stroke limits

Mechanics should measure pushrod travel regularly. If the stroke exceeds manufacturer-specified limits, that’s a telltale sign your brakes are dangerously out of adjustment.

Inconsistent or Delayed Brake Application

When the brake pedal is engaged but there’s a lag before braking occurs, your trailer may be experiencing:

• Sticky S-cams that are not rotating freely
• Service chamber issues, including a torn diaphragm
• Slack adjusters out of sync between wheels

This delay can be fatal in high-speed or emergency scenarios. Synchronization across axles is critical to maintaining control under load.

Overheating Hubs and Brake Drums

After a run, if your hubs or drums are hot to the touch—or worse, smoking—you're likely dealing with dragging brakes. This could be the result of:

• A stuck S-cam
• Misadjusted slack adjusters
• A failing return spring keeping the brake shoes from disengaging

These situations accelerate wear and increase the risk of fire in extreme cases. Using an infrared temperature gun during post-trip inspections can help catch this issue before it escalates.

What to Do When You Suspect Brake Issues

If you observe any of these symptoms, take immediate action. Here’s a quick response plan:

1. Pull over safely and secure the vehicle.
2. Perform a visual inspection of the brake components.
3. Check air pressure levels and inspect for leaks.
4. Contact a professional technician if adjustments or replacements are beyond your capability.
5. Schedule a full brake inspection and service immediately.

For fleets, this underscores the value of routine BIT inspections (Basic Inspection of Terminals) every 90 days as mandated by California law. These inspections can catch issues long before they snowball into hazardous failures.

Inspect Your Brakes Today

From S-cams and slack adjusters to service chambers and air lines, every part must work in harmony. By staying vigilant for the warning signs—like uneven braking, abnormal noises, longer stopping distances, or visible wear—you can prevent dangerous failures, reduce downtime, and keep your rig roadworthy.

If you require brake repairs near Fontana, CA, contact JB Trailer Service today!