Today we are going to take a look at Dexters 12 Electric Brake Assembly left hand side, part number 3-105-09. This is a 12 by 2 assembly, we will measure the diameter across the shoes, and theres our 12 figure. Then we can measure the width of the shoe, and theres our 2 mark. When paired up with the right hand side assembly these brakes are good for axels rated up to 6,000 pounds. There are 2 different mounting configurations predrilled into the assembly back, you can either use the 5 bolt assembly with the smaller bolt holes, or you can use the Alco, or Hays 4 bolt assembly with the larger bolt holes. So check your axel to see if you have either the 5 bolt or the 4 bolt off set Alco / Hays pattern.
There are a pair of wire leads that you will use to make your electrical connections. It doesnt matter which you use for ground and which you use for brake feed so long as you have a good solid electrical connection. These are manually adjusting brakes so when you first install them, and over time as the shoes will wear, you will need to adjust the tension. To do this you will rotate the star wheel on this pin that will open up the brake assembly shoes, and set your tension. This is an electric brake assembly, so you dont want to use it on boat or marine trailer applications.
The way the assembly works is the wheel and drum rotate around the assembly, and you press the brakes inside the vehicle. This magnet will become charged and stick to the inside of the hub drum. As the drum rotates its going to drag on this magnet pulling this arm which in turn will open up the brake assembly and apply pressure. You can tell that this is for the left hand side because the short shoe over here will go to the front of the trailer, and the long shoe here will face the back of the trailer. And that does it for Dexters 12 Electric Brake Assembly for 4 bolt Alco / Hays, or 5 bolt, part number 23-105-09.
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Questions and Comments about this Video
I have a 2012 Rockwood Tent Camper Freedom model 1940LTD. Althought it doesnt have breaks I would like to install electric breaks. Can you suggest which model break assembly I should purchase?Thanks for your help.PS I already have the tow vehicle wiring and controller.Rich
comment by: richard b - 1/16/2013
The necessary brakes will dependent on the axle weight rating as well as wheel size. There should be a plate or tag on the axle with information regarding a weight rating. The most common by far are 10 inch assemblies good for use on axles with a 3500 pound weight rating. Note that they are left/right hand sensitive. Also, the axle will need mounting plates welded onto it. This is not something we recommend the DIY guy to do as the plates must be perfectly square and concentric.
Patrick B - 2/1/2013This Old Trailer: Changing Hydraulic Trailer Brake to Electric
Today on This Old Trailer we are going to replace hydraulic brakes with electric brakes. Basically it is going to be a matter of taking off the tires, removing the hubs, go ahead and removing the backing plates and drain the hydraulic lines of fluid, and then going ahead and bolting on the new brakes. We will start off, obviously, by taking the wheels off. OK, go ahead and remove the dust cover here. It is an E-Z Lube spindle so this has a tang washer that we need to bush back down so we can unlock the castle nut right here. Just push it back down. Now we should be able to take the hub right off. The next task is to go ahead and disconnect the hydraulic lines. We have that disconnected. Now we need to pull the clip out so we can release this part here. And that is just a little piece of metal right here that you can just pry out. Alright, now we can unbolt this at the back of the hydraulic backing plate. Alright, now we can unbolt the backing plate from the flange on the axle. Now we are down to our bare axle. We will clean it up a little bit and then reinstall the brakes. 1:24
This Old Trailer: Electric Trailer Brake Installation Part 1
Alright, today on This Old Trailer, what we are going to do is install electric brakes. Right now this trailer does not have any brakes on it whatsoever, so it has two drag axles. So the first thing that we need to do is go ahead and take off the rear wheels. And then we will go ahead and take off the hubs. At this point we will take off the dust cap on our axle. And basically what you want to do is on this particular unit we have an E-Z Lube cap, so it fits kind of tight. It is a good idea to go ahead and rotate the hub and lightly strike it and then I will just back it off with a screw driver behind the flange. And then pry it off. Alright, let us wipe off the excess grease on the end of the spindle here and we will get to our tang washer. And we will release it so we can back off the castle nut. Alright, we have it cleaned up a little bit. Now right here, this is the tab I was talking about. That is our tang washer. Take this. Push it down flat to the flat spot on our spindle and then you can take the castle nut off. 1:07
All right today we are going to show you a typical brake inspection. Basically what we are going to do is take off the brake hub here and we are going to inspect the brakes, the linings, the springs, and the display cylinder inside. First off we will go ahead and take off the dust cap. In this case it is a bearing buddy. Next, is taking out the locking pin. There is either a cotter pin that goes in the center here but once you get that lock washer off you have to go ahead and just take off the nut and pull your whole hub off. First thing you want to check for is grease on the linings, and sure enough we have got grease all over these linings here. Also on this side here and probably smeared around over to the other side as you can tell.
All right today we are going to show you how to bleed hydraulic brakes on a trailer. First off you want to top off your master cylinder, with appropriate fluid. To pump the fluid from the master cylinder out, there is a couple of different ways of doing it. Sometimes it will have the emergency lever the and the safety chain will pull. Okay what you can do is unbolt the plate that holds the lever in place and then use that lever to actuate the master cylinder and force the fluid through. Some of them, you are going to have to go where the ball goes and manually activate it. Pull it in and out. Or like on this model here there might be a little lever underneath here that you could use.
Trailer Hub Brake Magnet Replacement Demonstration
When one wheel does not seem to be stopping as quick as the others it may be because the brake magnet needs to be replaced. We put together a short video to help you recognize this problem and to show you how easy it is to fix it. Keep your trailer safe for yourself and others on the road by checking and replacing parts like the brake magnet when needed.
Trailer Brakes and Wiring Installation
Today we are going to show you how to install brakes on a trailer that does not have existing brakes. It is actually pretty easy to do. It is just very time consuming. There are a couple of things you want to look out for before you start. You want to step behind your trailer, and look behind the existing hub you have. Make sure you have a flange like this on the axle. It is this 4-bolt flange on here; if you have that on your axle you are pretty much home free. This size flange has four bolts. You will see it on 3,500- pound axles like we have here. You also see it on 2,000- pound axles. On a 3,500 -pound one you would probably use a 10- inch drum and on a lighter axle, 2,000 pounds, you probably would use a 7- inch size. Also you notice we have the hub missing. We have to take that off because the hub and drum assembly is all in one piece. It is not like the automotive application. You have to take off the old hub, discard it, and start off fresh.
