Many trailers rely on the inertia of the car for stopping power. While this is acceptable on trailers that only travel short distances or trailers that are infrequently used, trailers that transport boats or travel trailers require slightly more sophisticated methods, such as installing a braking system.
Determine what kind of brake system you should install on your trailer. While simple systems such as electric brakes exist, more complex hydraulic systems are available. Examine such factors as what distance your trailer will be traveling, as well as the environment, such as a crowded city highway or an open country road.
Use a tire iron to loosen the lug nuts on the trailer tires.
Lift the trailer frame using a stable jack or a car lift. Since the brake installation requires being beneath the trailer, take extra care to make sure the trailer is stable before attempting to perform any work.
Remove the lug nuts and set them in a secure place. Then remove the tires from the trailer frame.
Remove the lug nuts and set in a secure place. Then remove the tires from the trailer frame.
Remove the spindle washer and spindle nut that are located underneath the trailer hub. Do not discard them, as they will need to be replaced after the trailer brake is installed.
Locate the plate mount on the axle, a square-shaped piece of metal with four holes at the corners. This is where the brakes will be attached.
Mount the brakes onto the plate mount. Identify which brake is the left and right before you begin and stand behind the trailer to properly determine the trailer's left and right sides.
"Pre-pack" the brake bearings. Coat all the bearing rollers in grease, making sure that all the roller surfaces are thoroughly covered.
Insert grease into the hollow of the trailer hub, and then insert the rear bearing into the hub rotor.
Attach the outer bearing, thrust washer and spindle nut onto the hub rotor. Then use a wrench to tighten the spindle nut. Once the nut is tight, loosen it a quarter of a turn. Loosen and tighten the nut with your fingers until you cannot tighten it without using tools, and then fasten it in place with a cotter pin.
Install the brake tubing system if you are installing a hydraulic brake system. This will connect your trailer brakes with the brake coupler, located behind the trailer ball connector.
Bleed the trailer brakes. Locate the bleeder valve on each brake and then fill the brake coupler with brake fluid. Attach a clear tube to the bleeder valve, place a glass jar underneath the tube, then manually pump the brake coupler and check for air bubbles, repeating the test as necessary until no air bubbles appear.
Replace the tires, and then test the new braking system. Get a friend to turn the trailer tires as you manually engage the brake coupler. If the brakes have been properly installed, the tire will suddenly stop moving.
