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How to Adjust Atwood Surge Brakes

by Thomas West

Boat trailers, campers, horse trailers and rental trailers usually have one of two different types of braking systems. Electric trailer brakes rely on a controller in the tow vehicle and good electrical connections. Surge brakes, on the other hand, are completely automatic and independent of the tow vehicle. Atwood surge brakes rely on a hydraulic master cylinder mounted on the trailer tongue. Upon deceleration an actuator pushes brake fluid from the trailer's master cylinder, then through the brake lines and to the brakes at each wheel. The brakes must be adjusted periodically for proper operation.

Work on one side of the trailer at a time. Chock the wheels on the opposite side of the trailer you will be working on first. Place a floor jack under the axle on the side you want to raise first. Raise the trailer until the wheels are off the ground. Place a jack stand under each axle, then lower the floor jack.

Crawl under the trailer and locate the clip that covers the adjustment hole on the back side of the brake backing plate of the rearmost wheel. Pry the clip off with a flat blade screwdriver and place it aside.

Insert a drum brake adjustment tool or a flat blade screwdriver into the inspection hole until it comes into contact with the brake adjustment star wheel.

Rotate the rear tire and wheel in the direction of forward travel with one hand. Use the brake tool or screwdriver to turn the star wheel in a clockwise direction with the other hand until braking pressure is felt on the wheel.

Back the star wheel off in a counterclockwise direction five notches. Turn the tire and wheel in a forward direction to make sure it turns freely. Remove the brake tool or screwdriver, then push the clip back into the inspection hole until it snaps into place. Raise the wheels with the floor jack, then slide the jack stands out from under the trailer. Lower the floor jack and remove it from under the trailer.

Repeat entire procedure to adjust the brakes on the other side of the trailer.

Tip

  • If the wheel will not spin freely after adjusting the brakes, apply the brakes by pushing the actuator (located on the underside on the coupler) towards the back of the trailer, then release the actuator to release the brakes. Adjust the brakes again as per above.

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