Properly adjusted trailer brakes are paramount to safe towing. The key to adjusting your trailer brakes lies in achieving a balance: tight enough to provide effective stopping power without causing premature wear or brake lockup. This typically involves adjusting the brake shoes until they are just shy of contacting the drum when the brake pedal is released, ensuring a responsive and reliable braking system for your trailer.
Why Trailer Brake Adjustment is Crucial
Towing a trailer significantly increases the overall weight and stopping distance of your vehicle. Properly functioning trailer brakes distribute the braking load, preventing the towing vehicle’s brakes from being overloaded and reducing the risk of accidents. Neglecting trailer brake maintenance can lead to several dangers: increased stopping distances, jackknifing, trailer sway, and excessive wear on the tow vehicle’s brakes. Regular adjustment ensures optimal performance, minimizes wear and tear, and keeps you and others safe on the road.
Understanding Trailer Brake Systems
Before diving into the adjustment process, it’s essential to understand the types of trailer brake systems you might encounter. The two primary types are electric brakes and hydraulic surge brakes. Electric brakes, the most common type, use electromagnets to activate the braking mechanism within the drum. Hydraulic surge brakes rely on a master cylinder located in the trailer tongue, activated by the momentum of the trailer pushing against the tow vehicle during braking. The adjustment procedures differ slightly for each type. This article will primarily focus on electric brake adjustment, but we will touch upon hydraulic systems briefly.
Step-by-Step Guide to Adjusting Electric Trailer Brakes
This section provides a detailed guide to adjusting electric trailer brakes. Always consult your trailer’s owner’s manual for specific instructions and recommendations.
Step 1: Gather Your Tools and Materials
You’ll need the following:
- Jack and jack stands: To safely lift and support the trailer.
- Wheel chocks: To prevent the trailer from rolling.
- Brake adjustment tool (adjusting spoon or screwdriver): Specifically designed for turning the brake adjuster wheel.
- Torque wrench: For tightening lug nuts to the proper specification.
- Gloves: To protect your hands.
- Safety glasses: To protect your eyes.
- Wheel bearing grease (if re-packing bearings): During the adjustment, it’s a good time to inspect and re-pack the wheel bearings.
- Owner’s manual: For specific torque specifications.
Step 2: Safety First – Prepare the Trailer
Park the trailer on a level surface. Engage the parking brake on your tow vehicle and apply wheel chocks to the trailer wheels that you aren’t working on. Loosen the lug nuts on the wheels you’ll be removing. Use the jack to lift the trailer and secure it on jack stands. Remove the wheels.
Step 3: Locate the Brake Adjustment Slot
On the backing plate of the brake assembly, you’ll find an adjustment slot. This slot is typically covered by a rubber plug. Remove the plug to access the brake adjuster wheel.
Step 4: Tighten the Brake Shoes
Using your brake adjustment tool, turn the adjuster wheel in a direction that expands the brake shoes. This usually involves pushing upward on the tool. Continue turning the adjuster until the brake shoes make firm contact with the drum, making it very difficult or impossible to turn the drum by hand. You may hear a clicking sound as the adjuster engages.
Step 5: Back Off the Adjustment
Now, carefully back off the adjustment by turning the adjuster wheel in the opposite direction. The goal is to allow the drum to turn freely with a slight drag. A good rule of thumb is to back off the adjustment until you hear 8-12 clicks of the adjuster wheel. This ensures the brake shoes are close to the drum without binding.
Step 6: Test the Drum
Spin the drum by hand. It should rotate freely with a slight, consistent drag. If the drum is too tight, back off the adjustment a little more. If it spins too freely, tighten the adjustment slightly.
Step 7: Repeat for All Brakes
Repeat steps 3-6 for all brake assemblies on your trailer. Ensure each brake is adjusted consistently for balanced braking.
Step 8: Replace the Plug and Reinstall the Wheel
Replace the rubber plug in the adjustment slot to prevent dirt and debris from entering the brake assembly. Reinstall the wheel, tightening the lug nuts by hand in a star pattern. Lower the trailer to the ground and torque the lug nuts to the manufacturer’s specified torque using a torque wrench.
Step 9: Road Test
After adjusting all the brakes, perform a road test in a safe, controlled environment. Start at a slow speed and gradually increase it, testing the braking performance. Listen for any unusual noises and feel for any pulling or uneven braking. If necessary, readjust the brakes to achieve optimal performance.
Hydraulic Surge Brakes: A Brief Overview
While electric brakes are adjusted via the star wheel mechanism described above, hydraulic surge brakes have a different adjustment procedure. The primary adjustment on these systems involves ensuring the master cylinder in the actuator tongue is properly filled with brake fluid and that the actuator moves freely. While minor adjustments may be possible on individual brake assemblies similar to electric brakes, major issues usually require professional repair. Check the hydraulic fluid level regularly and inspect for leaks.
Frequently Asked Questions (FAQs)
Here are some frequently asked questions to further clarify the process and address common concerns.
1. How often should I adjust my trailer brakes?
Trailer brakes should be inspected and adjusted at least every 3,000 miles or every six months, whichever comes first. More frequent adjustments may be necessary if you tow frequently or in demanding conditions.
2. What happens if I don’t adjust my trailer brakes?
Neglecting brake adjustment can lead to uneven braking, increased stopping distances, premature brake wear, and potential accidents. It can also damage the tow vehicle’s braking system.
3. How do I know if my trailer brakes need adjusting?
Signs that your trailer brakes need adjustment include:
- Longer stopping distances.
- Uneven braking or pulling to one side.
- A spongy or low brake pedal in the tow vehicle.
- Squealing or grinding noises from the brakes.
- Excessive heat buildup in the brake drums.
4. Can I adjust my trailer brakes myself, or should I take it to a professional?
If you have basic mechanical skills and a good understanding of trailer brake systems, you can adjust them yourself. However, if you are uncomfortable or unsure, it’s best to consult a qualified mechanic.
5. What is the correct “drag” I should feel when spinning the drum?
The “drag” should be slight but consistent. You should feel some resistance, but the drum should not be overly difficult to turn. Think of it as the resistance you’d feel turning a slightly sticky knob.
6. What if I can’t get the drum to turn after tightening the adjuster?
If the drum is completely locked, you’ve tightened the adjuster too much. Carefully back off the adjustment until the drum can rotate. Be patient and avoid forcing anything.
7. How do I adjust hydraulic surge brakes?
Hydraulic surge brake adjustment primarily involves checking and maintaining the hydraulic fluid level in the actuator. Inspect the actuator for smooth movement. Fine-tuning adjustments may be possible at the wheel cylinders, but complex issues require professional attention.
8. What is the purpose of the rubber plug in the adjustment slot?
The rubber plug protects the brake adjuster mechanism from dirt, water, and debris, which can cause corrosion and malfunction. Always replace the plug after adjusting the brakes.
9. What type of grease should I use for my wheel bearings?
Use a high-quality, wheel bearing grease specifically designed for trailer applications. Synthetic greases often provide superior performance and longevity. Refer to your trailer’s owner’s manual for specific recommendations.
10. How do I troubleshoot uneven braking after adjusting my trailer brakes?
Uneven braking could be caused by several factors, including:
- Incorrect brake adjustment on one or more wheels.
- Contaminated brake shoes or drums.
- A faulty brake controller in the tow vehicle.
- Damaged or worn brake components.
Inspect each brake assembly carefully and make any necessary adjustments or repairs.
11. Is it necessary to replace brake shoes and drums during brake adjustment?
Not necessarily. However, if the brake shoes are worn below the minimum thickness specification or the drums are scored, cracked, or warped, they should be replaced. Regular inspection is crucial.
12. What is a breakaway switch, and how does it relate to trailer brakes?
A breakaway switch is a safety device that automatically applies the trailer brakes if the trailer becomes detached from the tow vehicle. It consists of a cable attached to the tow vehicle and a pin inserted into a switch on the trailer. If the trailer separates, the cable pulls the pin, activating the trailer brakes. Always ensure the breakaway switch is properly connected and functioning correctly before towing.