How to Check the Electrical Brakes on a Trailer

Most trailers come equipped with electric brake shoes, which are designed to stop the trailer wheels by applying pressure to the surface of the brake drums. When the brake pedal inside of the tow vehicle is depressed, the brake controller relays the corresponding compression information to the brake shoes. The brake shoes then push against the brake drum according to the distance the brake pedal is depressed. Replace the brake shoes when they wear down to a thickness of 1/8-inch.

Instructions

1

Park the trailer on a flat surface and disconnect the tow vehicle from the trailer.

2

Loosen the lug nuts on both rear wheels one-quarter turn counterclockwise with a tire tool.

3

Jack up the driver side rear of the trailer and place a jack stand under the rear axle about 12 to 14 inches away from the driver side wheel backing plate. Lower the driver side axle onto the stand. Move the jack to the passenger side rear of the trailer. Jack the trailer up and place a jack stand under the rear axle about 12 to 14 inches away from the passenger side rear wheel backing plate. Lower the passenger side axle onto the stand and leave the jack in place.

4

Finish removing the lug nuts from both wheels. Pull the wheels off and place them flat down on the surface. Move to the driver side rear brake drum and tap the dust cap off of the front of the drum with a rubber mallet. Remove the cotter pin from the castle nut and the spindle with the pliers. Loosen and remove the castle nut with a ratchet and a socket.

5

Grab the brake drum with your hands and shake it back and forth until the wheel bearing inside of the drum loosens up from the spindle. Pull the bearing and the washer off of the spindle. Pull the drum off of the brake shoes and place it on the ground. If the drum is stuck, tap it with a rubber mallet until it loosens.

6

Inspect the brake shoes for the proper thickness, which should be no less than 1/8-inch. Make sure that the magnet is still attached between the two brake shoes. Also make sure that the return springs, retainer springs, retainers and the retainer clips are all attached. Inspect the brake drum for damage, such as wear or grooving. Replace the drum if the damage is excessive. Slide the brake drum back over the brake shoes and reverse the steps above to reinstall the wheel hub. Torque the castle nut to 35 foot-pounds with a torque wrench and a socket.

7

Slide behind the brake assembly backing plate and locate the rubber plug on the back of the backing plate. Remove the rubber plug from the access hole with a flat head screwdriver. Adjust the brake shoes to the proper distance from the surface of the brake drums. Start by shining the flashlight through the access hole to locate the star gears on the brake shoe adjuster wheel. Slide the end of the brake shoe adjuster tool onto one of the star gears and turn the gears clockwise until they stop turning. Grab the wheel and attempt to turn it. If the it will not turn, this means the brake shoes are fully compressed to the surface of the brake drums.

8

Turn the star gears counterclockwise to position the brake shoes away from the brake drum. Turn the wheel at the same time. Once the wheel begins to turn with no restrictions, stop turning the star gears and reinsert the rubber plug. Slide the wheels back on and screw the lug nuts on tightly. Jack up the trailer and remove the jack stands. Lower the trailer to the surface and remove the jack.

9

Move to the passenger side brake drum and repeat the same process described above. After both rear electric brake shoes have been inspected, slide the wheels back on and screw the lug nuts on tightly.

10

Jack up the trailer back and remove the jack stands. Lower the trailer to the surface and remove the jack. Finish tightening the lug nuts firmly.