How to Repair the Surge Brake on the Tongue of a Boat Trailer

Replacing the surge brake coupler is the best way to repair the system.

Trailer brakes are required in every state if your trailer is a specific mass. These systems are intended to mitigate the loss of braking when towing a trailer. Two types of breaks are used: electric and surge brakes. Surge brakes convert the force exerted on the trailer's coupler into braking power at the wheels. They do this by compressing a hydraulic master cylinder, forcing fluid down the brake lines. Over time the coupler can fail due to exposure to the elements.

Things You'll Need

• Socket set and ratchet
• Open ended wrenches
• Torque wrench
• DOT3 brake fluid
• Bleeder hose
• Glass

Instructions

1. Remove the bolts that secure the current surge coupler to the trailer with a socket and ratchet.

2. Loosen the bolt that secures the brake line to the coupler with an open ended wrench. Remove the broken coupler from the trailer.

3. Take this coupler to your local parts store and purchase one that matches in size and bolt pattern.

4. Slide the new coupler into position on the trailer's tongue aligning the bolt holes. Insert the supplied bolts through the holes and install lock washers and nuts. Torque the nuts to 80 foot-pounds.

5. Fasten the brake line to the coupler with a wrench.

6. Remove the master cylinder cap on the coupler. Fill the reservoir to 3/4 full with DOT-3 brake fluid.

7. Remove the back two bolts that secure the breakaway lever to the coupler. Loosen the front two bolts on the breakaway lever and rotate the breakaway locks to the side. Tighten the front two bolts.

8. Pull the breakaway lever forward until vertical and then return to the normal downward position. Repeat this up and down action until air stops bubbling in the master cylinder.

9. Loosen the bleeder valve on the first wheel brake with a wrench. Install a bleeder hose on the end of the valve and submerge the other end in a glass container of brake fluid. This is done to observe the air bubbles in the glass.

10. Pump the breakaway lever until air bubbles stop appearing in the glass. Close the valve and repeat this process for each brake. Replenish the brake fluid in the master cylinder between brakes to maintain at 3/4 full.

11. Install the master cylinder fill cap. Loosen the two front bolts on the breakaway lever. Rotate the breakaway locks to their original position . Install and tighten the two rear bolts and washers and tighten the four bolts to 90 to 120 inch pounds of torque.

Tips & Warnings

• Test the trailer's brakes on a quiet country road or abandoned parking lot before heading out on a trip.

References

• Titan: Instruction to Surge Braking

Resources

• Towing World: Towing Laws Listed by State