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Dexter DX7.5L A-60 Brake Actuator Review and Installation

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Review and How to Install the Dexter DX7.5L A-60 Brake Actuator


Hey everybody, Ryan here at etrailer. Today we're going to be taking a look at and showing you how to install the Dexter axle surge brake actuator with electric lockout. So this actuator is going to be set up for disc brakes. And disc brake conversions are becoming very popular on a lot of trailers, nowadays. People are getting away from the old drum style brakes and going to the disc. And that's because the stopping performance is so much better, a little more reliable and so on.

And so a lot of these trailers are trailers that are a few years old came set up with drum brakes. Well the problem is many times the actuator coupler isn't designed to work with disc brakes. So when you go to upgrade them, you're going to need to find a coupler or an actuator that is compatible with disc brakes. And that's exactly what our customer actually did today. We upgraded the brakes to discs from drum redid the lines and everything else.

And so this was a perfect choice to make the package complete. So the way a surge brake actuator works is pretty simple. Believe it or not. So there's a master cylinder inside of here that's full of fluid. That's connected to your brake line.

And whenever you apply the brakes in your vehicle or start to slow down the trailer is going to want to kind of go towards the back of your vehicle when that happens, what it's going to do. It's kind of tough to do it by hand but you could see that's going to move in, like so, and when that happens, that's going to pressurize or send fluid to your brakes and apply them. And then once you start towing again it'll pull itself back out and release the pressure. So really straightforward how it works. Really not a whole lot to it there.

This is going to work for ball mounts or balls rather that are two inches in size. So really common size and the coupler mechanism itself is a little bit different. It's kind of unique. It seems like it'll work out real well. To open it up, You will simply just kind of push over on that and then pull your pin out. You can do one or the other first don't really matter but then you'll go ahead and put your ball in there close that back up, and then reinstall your pin. And by putting that pin in, that's going to prevent any accidental disconnect. So with the pin in there you can only open it up about this much. So that'll help put your mind at ease too. And you don't have to worry about using some type of separate component to make sure everything is locked down. So, one thing that is nice about this setup is the fact that it is a electric reverse lockout. So if you take a look inside there on top of the master cylinder, there's going to be a solenoid. And when you hook up your ground wire and this blue wire to your reverse light circuit on your trailer, whenever you're backing up you're not going to have to worry about the brakes applying. So that's nice, convenient, especially when you're launching your boat onto the ramp. You're not going to have to fight your brakes or anything else. The master cylinder is made from aluminum as opposed to a plastic or a steel type cylinder. So that's nice, you know, it's strong and we're not going to have to worry about it rusting out or anything like that. This is going to have a pull away cord. And this is there. It's a safety measure, more or less. What this is gonna do is connect to your hitch. And if you we're to accidentally become disconnected, what this would do is pull off inside of here and it would set the brakes on the trailer. So to help bring everything to a safe and a little more predictable stop. So I thought it'd be useful just to kind of set our old one next to the new one, just to kind of compare them. And as you can see they're almost identical in size and style. Now there's a handful of different reasons why you would want to replace your old one. I'd say one of the reasons being maybe this is just damaged, you know, maybe you backed up your trailer wrong or something like that and tweaked this or potentially if it sat for a long time maybe it's difficult to hook up to your ball. But one of the more common causes is the master cylinders just go bad over time. You know, if they sit for a long time out in the weather they can start to rust out and leak fluid and that's not gonna allow your brakes to work properly. Another reason is the bushings inside of here too. Same thing with them. They just get worn out over time and your brakes aren't going to work like they should. And it's a lot easier just to put a whole new unit on as opposed to just replacing those individual components. So if that's your case I'd definitely recommend just grabbing a whole new setup. Another reason would be maybe you want to have that reverse lockout, like we talked about. Which you look at our new one. That's what this solenoid is here. Our old one does not have that. So maybe that's a feature that you really want. I know I would. And that's another reason you would replace this. Or, like in our case, maybe it's a number of reasons. In our case today, our customer actually converted his Ranger boat trailer to disc brakes. And this current setup here would not work with disc brakes. This one, however, the new one is set up to work with those disc brakes and only disc brakes. So that can be another reason. I will say, though, if your trailer has drum brakes you're not going to be able to use this setup but the good news is there's many other options available right here at etrailer that'll work with those. So this is going to be rated for 7,500 pounds. So pretty high number. So it'll work with a lot of different trailers and boats particularly and this is also going to have a zinc finish on it. And that's pretty important since everything's going to be near the water, but these going primarily on boat trailers always going to have that moisture and so that zinc finish is really going to help keep this looking good and functioning properly. But other than that, at the end of the day after kind of working with this I would feel comfortable putting it on my own trailer. It seems to work out really well. Everything fit nice and would make a great replacement or even upgrade. So what's convenient about this setup too, you can actually install it a couple of different ways. You can bolt it on your trailer. Tongue needs to be three by four inches. And so this can bolt right onto it. Or what you can actually do, is remove the inner portion by taking off these snap rings and replace just that part. And that's exactly what we're going to do today here on our Ranger boat trailer. Since everything here is fine we're not going to worry about doing anything with that. We're just going to replace this center section. So should be pretty straight forward and not a whole lot of work. But speaking to that, let's go ahead and put it on together now. So before we actually start installing this I just want to mention, you know, every trailer is going to be set up a little bit different. So depending on your application, this install may vary a little bit. But with that being said, what we're going to do here today will get you pointed in the right direction. So as I mentioned, we're just going to be using the inner portion here and not worry about this tongue or this metal bracket. So we're going to remove these snap rings to slide everything out. Now, if you're not just replacing this inner portion and using the whole thing, you would have to remove the current coupler on your trailer, slide this over the tongue and then you can use these holes here to bolt it all down. So to get our snap rings off, you're going to need a pair of pliers like this We'll carefully get our snap ring removed. So we got that ring off. Set it to the side. Pull off the washer. And we're going to do that same thing to this one as well. Then with these snap rings off, what we're able to do is carefully remove our pins there. Slide this out. And then this piece should come right off. Now what you need to do before you actually remove everything out of your old trailer. If yours already had a actuator similar to the one we're putting on, you are gonna need to remove any wiring as well as the brake line that runs to the back of it. You'd simply unthread that nut to get the brake line removed. When you do that, I do suggest using what's called a line wrench that looks like this, and that's going to really help get around that fitting there and get a little more contact, a little more surface area. That way you don't strip the nut out here. Once you have everything disconnected we can remove these snap rings from our existing setup just like we did the new one. So I already took the one off on the back there towards the back of the trailer. Go ahead and pull this one off as well. Then what we should be able to do is remove the pins, by pushing them out. These ones may be a little bit trickier since they do have some wear on them. So if your pin is sticking a little bit and difficult to get out, it may be necessary to use a punch and a mallet and just assist it out a little bit. Once we get that one removed though, we should be able to grab it and work it out from our trailer. So at this point we can take our new one and slide it into position. I'm going to start by kind of just feeding our wires in first. This will just push those through. Just trying to get them all the way through there. That way, when we slide this in they don't get pinched or kind of jammed up in there. I'll just kind of give them a good twist. They'll stay together. Just feed them all the way back. Once we get close enough, we should be able to kind of reach up on the backside grab them and pull them through. So once we have those pushed through, what you can do is carefully take out this pin and try to kind of hold everything steady. And we're just going to work this into place. And once we get about halfway through probably we're going to have to remove this pin so we can continue forward. Get lined up and push both of our pins back into position. So once you have bot the pins through, you can replace your snap ring and washer. And I just want to mention, too the one here closest to the front, that's going to have kind of this plastic bushing almost and you can see one side is going to be beveled. It's going to be angled. You want that angle side to face this way towards the trailer. So we'll get that slid on get our snap ring and snap it back into position. At this point, what we can do is hook up the two wires coming out of our solenoid, the white wire and the blue wire. The white wire is going to get grounded to the trailer and the blue wire's going to hook up to the reverse light circuit. In our case, our trailer already has a ground post here with a wire on it. It's the white one and the reverse light wire has already been ran too. And that's this blue one. So what you're going to do is strip back the insulation and that'll expose the wire underneath. I like to give them a good twist. And to connect everything, I'm going to use heat shrink butt connectors. These aren't included, but you can grab them here at etrailer. So that butt connector's going to slide over the bare end of the wire, you're going to crimp it down and just hook them up to the corresponding wire. I'll do the same thing for our white wire. So once you have them hooked up, since these are heat shrink butt connectors I'm going to come back with a heat gun and seal up the ends. So what I went ahead and did was just tape up our connections just for a little bit of extra protection. And then I just kind of zip tied everything up, nice and neat. Now with that done, We can hook up our brake line here. Now in our case, our brake line was a little long. That's why you see these bends in it to help not only line it up but to make it the proper length. If yours is too long, you've got a couple options. You can bend it like this. However, I do suggest using a tool like this one. That way you get those nice clean bends in the line and you're not going to have to worry about breaking the line or kinking it, anything like that. Or you can always cut it to length and use a flaring tool. See, flare the end of the line, make sure you use the proper one and you can do it that way. So either way works. It's really just up to you. But what we're going to do is get this started. And what I like to do is get it going as much as I can by hand that way, you know, the threads are on there straight and everything's lined up properly. But I'm going to hold the nut there on the back of the master cylinder to stop it from spinning while we tighten up our brake line. Now with these, you don't need to crank down on them, by any means. What I like to do is just kind of get them snug and then just add a little bit more pressure because my thought is these brass fittings are somewhat easy to crack. So my thought is just get them snug. Once we fill up the system full of fluid we can check for any leaks. If you do happen to have a leak, not a huge deal we'll just have to tighten down our fitting a little bit more. Now, what you're going to want to do is just remove this cap here. So it'll pull off and then you're going to want to fill up the cylinder here full of brake fluid to the bottom of where that cap would sit. So not far from the top. So now what we need to do with the help from a friend is pump up our brakes. That way fluid will go through the whole system and we'll be able to bleed it from the air. The easiest way that I found is on the bottom of our coupler here. If you take a flat blade screwdriver, put it up through this hole, you can actually kind of ratchet that mechanism and see I'll ratchet that multiple times. What that's going to do is pressurize the system and then to let the pressure free or release the pressure you can push this button here. And so that's going to work that fluid in let this draw out and reset it and so on. So while we have someone up here applying the pressure, we can go back to our disc brake, our caliper, open up the bleeder screw and work all that air and fluid through the lines. So once it is pressurized, we can come here to our bleeder screw, and we're just going to crack it open and then close it. So in our case, we have fluid coming out. And so we know it's free of air. However you want to do this a few times. You want solid fluid coming out from here. You don't want any bubbles or foamy looking fluid, anything like that. And I want to mention as well you want to start on the side that's furthest away from your master cylinder. So whichever side has the longest line ran to it. That's how you want to bleed your brakes first. So you'll get that side done. Come over to the other side and constantly do that until you have solid fluid coming out of your brake calipers. Now something I do want to mention is whenever you are bleeding the brakes, you never want your master cylinder to run dry. So keep an eye on that and top it off as needed. If you are doing that and it runs dry you're just going to suck in a bunch of air and you're going to have to redo it all over again. I want to mention too this is going to take a few minutes having to pump this up manually. You are going to have to spend a little bit of time and do that. So if you do it a few times and no results, don't panic. Just keep at it and everything will go smoothly from there. But once it's bled, top off your master cylinder, take your plug, cap that up. And then we're just going to install the included cover here. And that'll finish up our look at and our installation of the Dexter axle surge brake actuator with the electric lockout..


Questions and Comments about this Video


Tom R.
I have a 2013 Nitro boat / dual axle trailer with disc electric brakes - the current master cylinder is 'gunked-up / fluid is brown jelly like'. I'd like to replace the brake actuator. What actuator do you recommend? The trailer 'swing arm with hitch' is 32" long, and it looks like the actuator is 17.5". Thank you Dexter DX7.5L A-60 Brake Actuator
Etrailer Expert
Reply from Jon G.

Just so that we are on the same page about everything - it sounds like you have the Dexter DX7.5L A-60 actuator which is designed for disc brake and an electric lockout, correct? Are you looking for this same actuator just with a different brand? Dexter Axle makes excellent products so I would think that something got busted and there was a leak inside your actuator that caused everything to get gunked-up.

Reply from Tom R.

@JonG yes, we are on the right page. Nitro told me that the original actuator is Dexter Model 80LP/85LP - is the DX7.5L A-60 actuator the same? I assume the 80 means 8,000lbs capacity, and the 7.5 is 7,5000 lbs capacity. the 500 lbs difference is not a big deal. is the DX7.5L A-60 actuator an inner?

Etrailer Expert
Reply from Jon G.

@TomR I was having trouble finding specs on the Dexter Model 80LP/85LP but what I can say is that couplers tend to be somewhat universal. The DX7.5L A-60 has mounting bolt holes that measure 2-1/2 inches (top to bottom) by 3 inches (side to side) on center. If that matches what you have then this should be a pretty straightforward installation for you.

Info for this part was:

Employee Jeff D
Installed by:
Jeff D
Employee Ryan G
Installed by:
Ryan G
Employee Joshua S
Video by:
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Employee Jacob T
Video Edited:
Jacob T

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