How To Adjust Dexter Self Adjusting Brakes

Many trailers and some vehicles are equipped with self-adjusting brakes, designed to automatically maintain proper brake shoe-to-drum clearance. While the "self-adjusting" moniker implies a hands-off approach, these systems occasionally require manual intervention to ensure optimal performance and prevent issues such as brake drag or reduced stopping power. This article details the process for manually adjusting Dexter self-adjusting brakes.

Understanding Dexter Self-Adjusting Brakes

Dexter is a prominent manufacturer of trailer axles and braking systems. Their self-adjusting brake assemblies typically utilize a star wheel adjuster located between the brake shoes. This adjuster is designed to turn incrementally during braking when the brake shoes are excessively far from the drum. However, factors like corrosion, infrequent use, or improper initial setup can hinder the self-adjusting mechanism.

Identifying Dexter Brakes

Before proceeding, confirm that your trailer or vehicle is indeed equipped with Dexter brakes. Look for Dexter branding on the axle, brake backing plate, or brake drums. Documentation accompanying your trailer or vehicle should also specify the manufacturer of the braking system. If unsure, consult with a qualified mechanic or trailer repair specialist.

Tools and Materials Required

Prior to beginning the adjustment process, gather the necessary tools and materials:

• Jack and jack stands: To safely lift and support the trailer or vehicle.
• Wheel chocks: To secure the wheels opposite the ones being worked on.
• Brake adjustment tool (or a flat-blade screwdriver): Specifically designed for manipulating the star wheel adjuster. A dedicated tool often provides better access and control.
• Gloves: To protect your hands from dirt and grease.
• Safety glasses: To protect your eyes from debris.
• Penetrating oil (optional): To loosen a stiff star wheel adjuster.
• Wheel bearing grease (optional): To lubricate the wheel bearings if removing the wheel and drum.

Step-by-Step Adjustment Procedure

The following steps outline the procedure for manually adjusting Dexter self-adjusting brakes. Always prioritize safety and consult your trailer or vehicle's owner's manual for specific recommendations.

1. Safety Precautions

Safety is paramount. Park the trailer or vehicle on a level surface. Engage the parking brake. Place wheel chocks behind the wheels opposite the ones being worked on. Loosen the lug nuts on the wheel to be adjusted, but do not remove them completely.

2. Lifting and Supporting the Trailer/Vehicle

Using a jack, raise the trailer or vehicle until the wheel is off the ground. Position jack stands under the axle or frame to provide secure support. Never work under a vehicle supported only by a jack.

3. Removing the Wheel (Optional)

Removing the wheel and drum provides direct access to the brake assembly. This step is recommended for thorough inspection and lubrication. If you choose to remove the wheel, completely unscrew the lug nuts and carefully remove the wheel. If removing the drum, it’s necessary to remove the wheel first.

4. Locating the Adjustment Slot

On the brake backing plate, locate the adjustment slot. This is typically an oval or rectangular opening covered by a rubber or plastic plug. The slot provides access to the star wheel adjuster.

5. Removing the Adjustment Slot Plug

Carefully remove the plug covering the adjustment slot. Use a screwdriver or a similar tool to gently pry it out. Be careful not to damage the plug, as it is needed to keep dirt and debris out of the brake assembly.

6. Adjusting the Star Wheel

Insert the brake adjustment tool (or flat-blade screwdriver) into the adjustment slot. The goal is to turn the star wheel adjuster. Determining the correct direction for tightening can sometimes be confusing, but usually, turning the star wheel upward (toward the top of the brake assembly) will expand the brake shoes. Rotate the star wheel a few clicks at a time.

After each few clicks, try to rotate the wheel drum (or the wheel if the drum is still attached) by hand. The drum should become progressively harder to turn. Continue adjusting until the brake shoes make firm contact with the drum, and the wheel/drum is very difficult or impossible to rotate by hand. You should hear the brake shoes lightly dragging against the drum.

Important: If the star wheel is very stiff, apply a small amount of penetrating oil to the adjuster mechanism through the adjustment slot. Allow the oil to soak in for a few minutes before attempting to turn the star wheel again.

7. Backing Off the Adjustment

After tightening the brakes, it's crucial to "back off" the adjustment slightly. This prevents brake drag and ensures proper brake function. Insert the adjustment tool into the slot and rotate the star wheel in the opposite direction (usually downward) until you can freely rotate the wheel (or drum) with a slight, consistent drag. This is the optimal adjustment point.

Proper adjustment allows the wheel to turn freely but still provides a responsive braking feel.

8. Reinstalling the Adjustment Slot Plug

Once the brakes are properly adjusted, reinstall the adjustment slot plug. Ensure the plug is securely seated to prevent contaminants from entering the brake assembly.

9. Reinstalling the Wheel (If Removed)

If you removed the wheel, carefully reinstall it onto the hub. Tighten the lug nuts by hand in a star pattern. Lower the trailer or vehicle and remove the jack stands. Using a torque wrench, tighten the lug nuts to the manufacturer's specified torque. Double-check the lug nuts after a short distance of driving.

10. Testing the Brakes

Before driving, test the brakes at low speed in a safe, open area. Ensure the brakes engage smoothly and evenly. Listen for any unusual noises, such as squealing or grinding. If you experience any problems, re-inspect the brakes and repeat the adjustment procedure. If the problem persists, consult a qualified mechanic.

Troubleshooting Common Issues

Despite careful adjustment, certain issues may arise:

• Brake Drag: This indicates that the brakes are adjusted too tightly. Back off the adjustment slightly further.
• Weak Brakes: This could be due to insufficient adjustment, worn brake shoes, contaminated brake linings, or a malfunctioning self-adjusting mechanism. Inspect the brake components and repeat the adjustment procedure. If the problem persists, replace worn or damaged parts.
• Uneven Braking: This can occur if the brakes are not adjusted equally on both sides of the axle. Adjust each brake assembly carefully to ensure even braking performance.
• Seized Star Wheel: Apply penetrating oil and gently try to free the star wheel. If it remains seized, the brake assembly may need to be disassembled for cleaning or replacement.

Preventative Maintenance

Regular maintenance can help prevent brake problems and extend the life of your Dexter self-adjusting brakes:

• Inspect the brakes regularly: Check the brake shoes for wear and tear, the brake drums for scoring or damage, and the brake lines for leaks.
• Lubricate the brake components: Apply brake lubricant to the moving parts of the brake assembly, such as the star wheel adjuster and the brake shoe contact points.
• Clean the brakes: Remove dirt, dust, and debris from the brake assembly on a regular basis.
• Check and adjust the brakes as needed: Even self-adjusting brakes may require occasional manual adjustment to maintain optimal performance.

Conclusion

Understanding how to manually adjust Dexter self-adjusting brakes is a valuable skill for trailer and vehicle owners. While the self-adjusting mechanism generally maintains proper brake clearance, occasional manual intervention is often necessary to ensure optimal braking performance and prevent potential safety hazards. By following the steps outlined in this article, you can confidently adjust your brakes and maintain a safe and reliable braking system. Properly functioning brakes are crucial for the safety of yourself, your passengers, and other drivers on the road. Regular maintenance and timely adjustments are essential to prevent accidents and ensure a safe journey.