Effectively adjusting your trailer’s electric brakes is crucial for safe towing, ensuring predictable stopping distances and preventing dangerous sway. This involves a methodical process of inspection, manual adjustment, and electronic tuning to achieve optimal braking performance across all wheels.
Why Properly Adjusted Trailer Brakes Matter
Hauling a trailer adds significant weight and inertia to your vehicle. Electric brakes are the primary safety feature designed to help you maintain control during braking. Properly adjusted brakes ensure that the trailer decelerates at the same rate as the tow vehicle, preventing:
- Jackknifing: When the trailer brakes are too weak, the tow vehicle can stop faster, causing the trailer to swing around.
- Sway: Unevenly adjusted brakes can cause the trailer to pull to one side during braking, leading to instability and potential loss of control.
- Increased Stopping Distance: Poorly adjusted brakes significantly increase the distance required to bring the combined vehicle and trailer to a complete stop.
- Premature Brake Wear: Over- or under-adjusted brakes can cause uneven wear and tear on brake shoes and drums or rotors, leading to costly repairs.
Understanding Your Trailer’s Electric Brake System
Before diving into the adjustment process, it’s important to understand the key components of your trailer’s electric brake system:
- Brake Controller: Located in the tow vehicle, this device sends an electrical signal to the trailer’s brakes, proportional to the tow vehicle’s braking effort. Modern controllers use inertia sensors to automatically adjust the braking force.
- Wiring Harness: Carries the electrical signal from the brake controller to the trailer’s brake magnets.
- Brake Magnets: Located inside the brake drums, these magnets are energized by the electrical signal and attract to the armature face on the backing plate, creating friction that actuates the brake shoes.
- Brake Shoes: These curved pads press against the inside of the brake drum (or rotor) to create friction and slow the trailer’s wheels.
- Brake Drums/Rotors: The rotating surfaces that the brake shoes press against.
- Adjuster Star Wheel: A small wheel with teeth that allows you to manually adjust the position of the brake shoes within the drum.
Step-by-Step Guide to Adjusting Electric Trailer Brakes
Here’s a detailed guide on how to adjust your trailer’s electric brakes:
Step 1: Safety First!
- Park the trailer on a level surface.
- Chock the wheels on the opposite side of the trailer you’ll be working on to prevent movement.
- Wear safety glasses to protect your eyes from debris.
- Engage the tow vehicle’s parking brake.
- Disconnect the trailer from the tow vehicle’s electrical system.
Step 2: Jack Up the Trailer
- Use a suitable jack to raise the trailer, ensuring you lift it high enough so the wheels can spin freely.
- Always use jack stands for safety. Never work under a trailer supported only by a jack.
Step 3: Locate the Adjuster Slot
- On the backing plate of each brake assembly, you’ll find an access slot, often covered by a rubber plug. This slot provides access to the adjuster star wheel.
- Remove the rubber plug. If it’s missing, you can purchase replacements at most auto parts stores.
Step 4: Adjust the Brakes
- Using a brake adjustment tool (or a small screwdriver), insert it into the access slot and engage the teeth of the star wheel.
- The direction you need to turn the star wheel depends on the brake assembly and the tool you’re using. The goal is to expand the brake shoes until they drag slightly against the drum.
- As you turn the star wheel, spin the wheel by hand. You should feel increasing resistance.
- Continue adjusting until the wheel becomes very difficult to turn. This means the brake shoes are firmly pressing against the drum.
Step 5: Back Off the Adjustment
- Once the wheel is difficult to turn, back off the adjuster star wheel until you can spin the wheel freely with a very slight drag. This is crucial. Brakes that are too tight will overheat and wear out quickly.
- A good rule of thumb is to back off the adjuster 6-8 clicks after tightening it fully.
Step 6: Repeat for All Wheels
- Repeat steps 2-5 for each wheel on the trailer. Ensure that all brakes are adjusted as evenly as possible.
Step 7: Replace the Rubber Plug
- Once the brakes are adjusted, replace the rubber plug in the access slot to prevent dirt and moisture from entering the brake assembly.
Step 8: Test the Brakes
- Lower the trailer and remove the jack stands and wheel chocks.
- Connect the trailer’s electrical connector to the tow vehicle.
- Adjust the brake controller in your tow vehicle according to the manufacturer’s instructions.
- Perform a series of slow-speed braking tests in a safe, open area to verify proper brake function. Listen for any unusual noises and feel for any pulling to one side.
- Gradually increase speed and braking force, continuing to monitor the trailer’s behavior.
- Fine-tune the brake controller setting as needed until the trailer brakes smoothly and predictably, without locking up.
FAQs: Deep Diving into Trailer Brake Adjustment
Here are some frequently asked questions that address common concerns and provide additional insights into trailer brake adjustment:
1. How often should I adjust my trailer brakes?
Trailer brakes should be inspected and adjusted at least once a year, or more frequently if you tow regularly or in harsh conditions. A good time to adjust them is before each major trip.
2. What tools do I need to adjust electric trailer brakes?
You’ll need: A jack, jack stands, wheel chocks, safety glasses, a brake adjustment tool (or a small screwdriver), a rubber mallet (optional), and potentially replacement adjuster hole plugs.
3. How do I know if my trailer brakes are adjusted too tight?
Signs of overly tight brakes include: Excessive heat in the brake drums/rotors, reduced fuel efficiency, a burning smell, and difficulty turning the wheels.
4. What happens if my trailer brakes are adjusted too loose?
Loose brakes will result in poor stopping performance, increased stopping distance, and potentially dangerous sway. The tow vehicle will do most of the work, leading to increased wear on its brakes.
5. Can I adjust trailer brakes myself, or should I take it to a professional?
If you’re comfortable working on vehicles and understand the principles of brake operation, you can adjust them yourself. However, if you’re unsure or lack experience, it’s best to consult a qualified mechanic.
6. What does “bedding in” trailer brakes mean, and why is it important?
“Bedding in” refers to the process of gradually wearing in new brake shoes to the brake drums (or new pads to rotors) to achieve optimal contact and braking performance. It involves a series of moderate braking events from moderate speeds.
7. What if the adjuster star wheel is seized or difficult to turn?
Try tapping the backing plate around the adjuster with a rubber mallet. You can also try spraying penetrating oil into the access slot. If it’s still seized, you may need to disassemble the brake assembly and clean or replace the adjuster.
8. How can I tell if my brake magnets are worn out?
Worn brake magnets will produce weak or inconsistent braking. You can test them using a multimeter to check their resistance. Consult your trailer’s manual for the proper resistance value.
9. What should I do if my trailer brakes lock up?
If your trailer brakes lock up, immediately reduce braking force and try to regain control. Adjust your brake controller to reduce the gain. If the problem persists, inspect the brakes for damage or contamination and consult a professional.
10. Are electric over hydraulic brakes adjusted the same way as standard electric brakes?
No. Electric over hydraulic brakes use a hydraulic actuator powered by an electric signal. The adjustment process is significantly different and usually involves adjusting the actuator and bleeding the brake lines. This system typically does not have the star wheel adjustment.
11. My trailer has self-adjusting brakes. Do I still need to manually adjust them?
While self-adjusting brakes are designed to automatically maintain proper adjustment, they can sometimes fail or become ineffective over time. It’s still a good idea to periodically inspect and manually adjust them if necessary.
12. What are some common signs of trailer brake problems that aren’t related to adjustment?
Other signs of trailer brake problems include: Unusual noises (grinding, squealing, scraping), pulsating brakes, uneven wear on the brake shoes, leaks in the brake lines (for electric over hydraulic systems), and a soft or spongy brake pedal in the tow vehicle. These issues may indicate the need for further inspection and repairs beyond simple adjustment.