How to Do an Electric Brake Job on a Trailer
Most types of cargo, boat and transport trailers are equipped with electric brake shoes. These are operated by an electrical control box inside the tow vehicle. When the brake pedal is depressed, the controller activates a magnet. The magnet moves the brake shoe linkage until the brake shoes have pressed against the inside of the brake drum. The amount of pressure the brake shoes apply is determined by how far the brake pedal is depressed.
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Things You'll Need
- Lug wrench
- Jack
- Jack stands
- Rubber mallet
- Pliers
- 1/2-inch drive ratchet
- 1/2-inch drive socket set
- Brake spring removal tool
- Brake spring retainer removal tool
- New electric brake shoe kit
- Flashlight
- Brake shoe adjusting tool
- Torque wrench
Instructions
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1
Pull the trailer onto a flat surface and disengage the tow vehicle.
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2
Loosen each of the lug nuts on the trailer rear wheels with a lug wrench.
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3
Raise the driver side rear of the trailer with a jack and place a jack stand under the rear axle about 14 inches away from the back of the brake shoe backing plate. Lower the axle onto the jack stand. Move to the passenger side rear of the trailer and do the same.
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4
Remove the lug nuts and the rear wheels from the rear axle. Move to the driver side rear brake drum and tap the dust cover off of the drum with a rubber mallet. Locate and remove the cotter pin from the castle nut with pliers.
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5
Loosen and remove the castle nut with a 1/2-inch drive ratchet and socket. Grasp the brake drum and move it back and forth until the roller bearing inside loosens from the spindle. Remove the bearing and the flat washer from the spindle. Pull the brake drum off of the brake shoes. If the drum is stuck, use the rubber mallet to loosen it.
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6
Remove the two upper brake shoe return springs from each brake shoe and from the top anchor pin using a brake spring removal tool. Loosen and remove the brake spring retainer clips from the front sides of each brake shoe with the brake spring retainer tool.
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7
Pull the top of the brake shoes apart by hand. Insert the spring removal tool inside the brake shoes and remove the two lower hold-down springs from each brake shoe and the brake shoe backing plate. Remove the brake shoes and set them aside.
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8
Place the new brake shoes onto the backing plate. Slide the bottom two hold-down springs over the retainers inside of each brake shoe with the brake spring tool. Attach the top two return springs to the anchor pin and to each brake shoe with the brake spring tool.
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9
Locate the small rubber plug inserted into an access hole on the brake shoe backing plate and remove it with pliers. Look through the hole with a flashlight and locate the star gears that are attached to the brake shoe adjuster star wheel.
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10
Slide the brake shoe adjuster tool inside the hole and onto one of the star gears. Turn the star gears clockwise until the brake shoes compress together enough to get the brake drum over the brake shoes. Slide the brake drum over the brake shoes and reinstall the flat washer, roller bearing castle nut, cotter pin and the dust cover. Tighten the castle nut with the ratchet and socket. Torque the castle nut to 35 foot-pounds using a torque wrench.
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11
Move to the passenger side rear brake drum and repeat the replacement process. Slide both rear wheels onto each axle and screw the lug nuts on tightly.
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12
Adjust both sets of brake shoes by turning the star gears on the adjuster wheel counterclockwise with the adjuster tool until the brake shoes are fully pressed against the surface of the brake drum.
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13
Try to turn the wheels by hand. If they do not move, then the brake shoes are fully pressed against the brake drum. Turn the star gears clockwise just far enough for the wheel to turn freely. Reinsert the rubber plug into the access hole on each backing plate.
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14
Raise the trailer and remove the jack stands. Lower the trailer to the ground and remove the jack. Finish tightening the lug nuts on each wheel
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1
Tips & Warnings
A long flat-head screwdriver can also be sued in place of a brake shoe adjuster tool to turn the star gears.
Stop adjusting the brakes once the wheels turn freely. If the brake shoes are positioned too far from the brake drum, they will not be able to press against the drum properly.
