The premise that self-adjusting trailer brakes never require manual adjustment is a dangerous myth. While designed to compensate for wear, these systems can and often do malfunction, necessitating a periodic manual inspection and adjustment to guarantee optimal braking performance and safety.
Why Manual Adjustment Matters
While the name implies a hands-off approach, the “self-adjusting” mechanism relies on specific conditions to function correctly. Factors like brake shoe contamination, corrosion in the adjuster assembly, or infrequent heavy braking can all hinder its effectiveness. Ignoring the need for occasional manual adjustment can lead to uneven braking, increased stopping distances, and potentially hazardous towing situations. A proactive approach ensures your trailer brakes remain reliable and responsive.
Understanding the Self-Adjusting Mechanism
Most self-adjusting trailer brake systems utilize a star wheel adjuster located within the brake drum. This adjuster is typically linked to a lever that engages during braking, usually when backing up and applying the brakes simultaneously. This action ratchets the star wheel, bringing the brake shoes closer to the brake drum, compensating for wear. However, this system is not infallible. The linkage can become corroded or gummed up, preventing proper ratcheting. Furthermore, the system relies on adequate friction between the brake shoes and the drum; if the brakes are consistently used gently, they may never fully engage the adjuster.
The Manual Adjustment Procedure: A Step-by-Step Guide
Before starting, ensure the trailer is safely supported on jack stands and the wheels are chocked. Safety is paramount.
Gathering Your Tools and Materials
You will need the following:
- Jack stands
- Wheel chocks
- Flathead screwdriver (or brake adjusting tool)
- Gloves
- Safety glasses
- Brake cleaner (optional, for cleaning components)
Accessing the Adjustment Slot
On the back of each brake backing plate, you’ll find an adjustment slot. This slot is usually covered by a rubber plug to prevent debris from entering. Carefully remove the plug, taking care not to damage it.
Tightening the Star Wheel
Using your flathead screwdriver or brake adjusting tool, carefully insert it through the adjustment slot and engage the star wheel. You’ll need to move the tool in small increments, turning the star wheel upward (towards the top of the brake drum) to tighten the brakes. Continue tightening the star wheel until the wheel becomes difficult to turn by hand. You should feel a noticeable drag.
Backing Off the Adjustment
Once the wheel is difficult to turn, back off the adjustment by turning the star wheel downward (towards the bottom of the brake drum). Typically, backing off 6 to 8 clicks will provide the optimal brake drag. The wheel should turn freely with a slight, consistent drag.
Repeating the Process and Testing
Repeat this process for each wheel on your trailer. After adjusting all the brakes, lower the trailer and remove the jack stands. It’s crucial to perform a test drive in a safe, controlled environment. Start slowly and gradually increase your speed, paying close attention to how the trailer brakes respond. Look for even braking and the absence of any pulling or grabbing.
Identifying Symptoms of Maladjusted Brakes
Recognizing the signs of maladjusted trailer brakes is crucial for maintaining safety. Some common symptoms include:
- Uneven braking: The trailer pulls to one side when braking.
- Increased stopping distance: It takes longer to stop the trailer than usual.
- Brake grabbing: The brakes lock up suddenly and unexpectedly.
- Brake noise: Squealing, grinding, or scraping noises coming from the brakes.
- Poor brake pedal feel: The brake pedal feels spongy or requires excessive effort.
If you notice any of these symptoms, inspect and adjust your trailer brakes as soon as possible.
Frequently Asked Questions (FAQs)
Here are some frequently asked questions that delve deeper into the intricacies of self-adjusting trailer brakes.
FAQ 1: How Often Should I Manually Adjust My Self-Adjusting Trailer Brakes?
There’s no one-size-fits-all answer. Annual inspection and adjustment are recommended as a baseline. However, if you frequently tow heavy loads or notice any of the symptoms of maladjusted brakes, inspect and adjust them more often.
FAQ 2: What Can Prevent the Self-Adjusting Mechanism from Working Properly?
Rust, corrosion, dirt, and debris are the most common culprits. Infrequent heavy braking can also prevent the self-adjusting mechanism from engaging. Additionally, worn or damaged components within the adjuster assembly can render it ineffective.
FAQ 3: Can I Convert My Manual Adjusting Brakes to Self-Adjusting Brakes?
Yes, it is possible to convert. However, it involves replacing the entire brake assembly, including the backing plate, shoes, and adjuster. This can be a complex and costly undertaking. Consider whether the benefit outweighs the expense.
FAQ 4: What Tools Are Specifically Designed for Adjusting Trailer Brakes?
While a flathead screwdriver can work, a dedicated brake adjusting tool is specifically designed for this purpose. These tools often have a specific angle and length to make accessing and manipulating the star wheel easier. They also minimize the risk of damaging the star wheel teeth.
FAQ 5: What Does “Backing Up and Applying the Brakes” Have To Do With Self-Adjustment?
Many self-adjusting mechanisms are designed to activate when the trailer is backing up and the brakes are applied. This action engages the lever that ratchets the star wheel, compensating for brake shoe wear. Some systems utilize forward motion for the same adjustment.
FAQ 6: What Type of Brake Cleaner Should I Use When Servicing Trailer Brakes?
Use a non-chlorinated brake cleaner specifically designed for brake systems. Avoid using general-purpose cleaners or solvents, as they can damage brake linings and other components.
FAQ 7: Can I Replace Just the Brake Shoes, or Do I Need to Replace the Entire Assembly?
You can typically replace just the brake shoes, as long as the other components, such as the brake drums and hardware, are in good condition. However, if the drums are scored or excessively worn, they should be resurfaced or replaced. Examine the springs and hold-down hardware, replacing as needed.
FAQ 8: What Is “Brake Drag,” and Why Is It Important?
Brake drag refers to the slight amount of resistance felt when turning the wheel after adjusting the brakes. A small amount of drag is necessary to ensure the brakes are properly adjusted and will engage quickly and effectively. Too much drag, however, can cause excessive wear and overheating.
FAQ 9: How Do I Know If My Brake Drums Need to Be Resurfaced or Replaced?
If the brake drums are deeply scored, cracked, or excessively worn, they should be resurfaced or replaced. Resurfacing can only be done a limited number of times before the drum becomes too thin. Consult a qualified mechanic for recommendations.
FAQ 10: What is the correct tightness of the brake adjusting nut and what should I use to measure it?
There is no adjusting nut outside the assembly. You are adjusting the star wheel through a small hole. The correct tightness is judged by feeling a slight drag on the wheel after adjusting and backing off the adjuster as described above. There is no torque specification involved in this adjustment.
FAQ 11: How do electric brakes work with the self-adjusting mechanism?
Electric brakes utilize an electromagnet to activate the braking force. When the brake controller sends current to the trailer brakes, the electromagnet is energized and pulls on a lever, which applies pressure to the brake shoes. The self-adjusting mechanism then ensures that the brake shoes remain properly positioned relative to the brake drum, compensating for wear.
FAQ 12: What happens if I over-tighten the self adjusting trailer brakes?
Over-tightening will cause the brakes to drag excessively, generating heat, increasing brake wear, and reducing fuel efficiency. In severe cases, it can lead to brake failure and even a fire. Back off the adjuster immediately to the recommended clearance.
Conclusion: Prioritizing Safety Through Vigilance
While self-adjusting trailer brakes offer convenience, they should never be considered maintenance-free. Regular inspection, manual adjustment when necessary, and a keen awareness of potential issues are essential for ensuring the safety and reliability of your towing setup. By understanding how these systems work and taking a proactive approach to maintenance, you can confidently hit the road knowing your trailer brakes are up to the task.