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Demco Hydraulic Drum Brake Assembly Installation

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How to Install a Demco Hydraulic Drum Brake Assembly


Today on our trailer, we'll be installing the Demco Hydraulic Brake Drum Assembly, 10"x 2-1/4" in size on the left-hand or driver side, part number 40716. For the right, or passenger side, part number 40715. To begin our install, we'll first go ahead and remove the wheels. To remove our hub drum assembly, we'll go ahead and first remove the dust cap. Next, we'll remove the castle nut. Once the castle nut's out of the way, we'll go ahead and pull the washer and outer bearing. Now with those out of the way, we can go ahead and remove the hub drum assembly. There are four fasteners that will need to be removed. Here looking from the outside in, we can see the bolt that goes through the backing plate and gets secured with a nut on three of the attachment points, and it's reversed here on the other one because if the bolt came through, it'd interfere with the wheel cylinder.

So the nut is on the back side of the backing plate for this attachment point. Note, we will not be reusing the old hardware as we have new hardware to install. Now we're ready to install the new backing plate and wheel cylinder. To determine if you've got the driver or passenger side set of backing plates without any identification, we'll look at the shoe length. The largest shoe goes to the rear of the trailer. We turn it around, we can see that this is marked for left, or driver side. And then we've got a brake line inlet for the wheel cylinder and the rubber cap covering up the brake bleeder. We're now ready to go ahead and install the backing plate.

Note, we're going to secure it with a new bolt, split-lock washer, and nut. Here's a way to remember it, is put the bolt through the backing plate, and then through the axle. Now, we'll tighten each fastener down finger tight until we have them all in place. With all of our hardware in place, we can go ahead and tighten each fastener down. Next, we're ready to reinstall the hub drum assembly. Slide the hub drum assembly on, and then our outer bearing. After the bearing, we put on our flat washer, the castle nut keeper, and then our castle nut.

Go ahead and use the castle nut to seat the bearings and to set our free load. Then we'll bend the tabs of the keeper over to prevent the castle nut from backing off. Now, because we have the easy lube axles with the grease zerk in it, we can take our grease gun and add additional grease as necessary. Once we have it fully greased, we'll then go ahead and reinstall the dust cap. We can use the access holes on the back side of the backing plate by removing the rubber grommet and adjusting up the brake shoes tp fit the drum assembly. And that does it for the install of the Demco Hydraulic Brake Drum Assembly, part number 40716 on our trailer. .


Info for these parts were:

Employee Jeff D
Installed by:
Jeff D

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