Changing out the surge brake actuator.

[FSH 210 Sport]

Okay,

A few weeks back I checked the brake fluid in the reservoir of the surge brakes… bone dry. I wonder how long it was like that since I’d never checked it before… boo on me. I’m still baffled at where the brake fluid went to. I know the brakes worked two years ago when the big Mule Deer Doe stepped out in front of me on the way to Lake Powell and I slammed on the brakes, the trailer started hopping and left big darkies on the road, damn that was close, my friend and his wife and their boxer dog were riding with me, he said nothing but his wife made a little squeak noise.

So, first thing I did was to put in brake fluid on the oft chance I could bleed them out and get by for a bit.. no das. I got old black fluid out first, the the newer fluid but it had air bubbles in it, and when I tried to manually pump the master cylinder I got lots and lots of little bubbles.. so bad master cylinder. After considering my life experiences I decided to just buy a new actuator, with the thought I‘d try and put a new master cylinder in the old one at some point and have a spare on the shelf.

While it did not help that I did this in the rain yesterday, it also did not help that there is nothing, and I mean zilch point poo poo about how to R&R this actuator in the instructions, did I say there was nothing instructions? Just want to make sure I drive that POINT home. First off, when you remove the big pins that hold that whole thing in, the wheels you can see In the pic fall out/down. Those pins also hold the guts in place, the master cylinder, the shock absorber etc…



You know, I just noticed that is there appears to be another removable plug on the bottom of the master cylinder reservoir.. huh.. why would you design something like that??? !!! I now have a plausible place for the fluid to have gone.

Have I mentioned yet that I’m not a big fan of surge brakes? That was before this escapade. One really good reason for having electric over hydraulic brakes is that you can use the manual brake bar on the controller in the cab to test your brakes each time you tow, this is a standard practice on my travel trailer, and if the trailer starts swaying you can apply the trailer brakes manually and get the sway under control. Finally, with modern integrated brake controllers being tied in with anti lock braking system, the anti lock braking system will also modulate the trailer braking to avoid wheel lock up and jack knifing.

Okay, what would have been really nice is if with the new actuator there were some wooden dowels that were only as wide as the actuator itself to hold the guts in place while you R&R it. I mean really, how much would a couple of freaking wooden dowels cost? What I had to do was to remove the folding part of the tongue, the safety chains etc.. and lay it upside down on my bench so I could remove the pins on the new actuator and then very carefully slide the new actuator into the swing tongue and then put the pins in. Even with me being very careful things jumped out of place and I had to hold my mouth just right to get things lined back up again. All of that could have been eliminated with two 5 cent dowels to hold things in place during assembly. Fuck. I don’t like to be negative but cmon.

I’m going to add fluid this morning and use a vacuum bleeder to pull new fluid through the system, and then my friend will be by later to use the manual pump on the actuator to do the final bleeding. I’ll try and get a couple of measurements for some dowels so that others can make them before disassembly/ reassembly.

Moral of this story, don’t be an idiot like me and not check the brake fluid for two years.

I’m also wondering how many folks out there have air in their surge brake system that causes excess travel on the actuator which makes for more slop when going from a stop to staring up again. Time will tell!

 

[Julian]

I need to work on my brakes too. Bled them last year and got them working....now they aren't again. What made you buy a complete replacement vs bleeding and testing?

 

[FSH 210 Sport]

I need to work on my brakes too. Bled them last year and got them working....now they aren't again. What made you buy a complete replacement vs bleeding and testing?

So I initially tried bleeding them and just kept getting air, and when I pumped the master manually there was nothing, no resistance at all and it was just making bubbles in the reservoir. This indicates a bad shaft / actuator rod seal.

Interestingly there was still brake fluid in the reservoir when I took the actuator apart, not as much as when I left it, and I have towed it a few hundred miles since discovering it was empty and trying to refill it and bleed it out. My truck is heavy and has huge brakes ( tow rating of 21,000#) so I didn’t notice it pushing like a lighter tow vehicle with less tow capacity might.

I just finished vacuum bleeding them and now there is resistance when I pump the master manually, and there are not anymore bubbles, just some circulation of fluid, there is still air in the system as it won’t pump to hard.

But unless you wrap the bleeders with Teflon tape you’ll get air bubbles past the threads of the bleeders when using a vacuum bleeder. My friend is coming by in a couple hours and we will bleed them the old fashioned way, and I will make sure there is no air in the system that way.

I have very little experience with these types of braking systems. With that in mind, and my own experience with rebuilding master / slave cylinders (rarely if ever worked) I decided I would forgo the past of trying to rebuild stuff and messing around with something I have little experience with and just buy a new one and do it once. As an fyi, you can buy a new master cylinder for $100 as opposed to buying the whole actuator for $350. Again, I didn’t want to try and save money only to find out something else was wrong and extend the repair time and hassle. I may go ahead and get a master cylinder assembly and replace the bad one and put the whole assembly on the shelf for a spare.

In your case, unless you can identify a leak somewhere else, I’d say your master cylinder has a leak some place. My suggestion would be to just get a new master cylinder and change that if you want to save $250.

I did not see a rebuild kit for the master by the way. I believe the website said it was a sealed unit??

If you are going to go that route make yourself some wooden dowels that are .739” in diameter and a touch under 3” long. When you go to remove the main pins, to remove the actuator, use the wooden dowels to push the metal pins out with. This will retain the wheels and the rest of the actuator parts inside the actuator housing so you can slide it out without things falling out. Or just lay it on the bench upside down.

These main mounting pins are not stainless! So when you reassemble the actuator be sure and lube the heck out of these pins for the metal wheels which support the actuator to ride on. And really, over time greasing these metal pins for the metal wheels should be a maintenance item to keep the actuator functioning smoothly.

 

[Babin Farms]

Like you I have a tow vehicle that is more than capable and have the same trailer brake issue with fluid disappearing with no visible leaks. I just keep the fluid topped off and watch to make sure the rotors are shined up after towing. I have a hard time justifying fixing it due to the trailer being steel and I am down here in salt water so eventually I’ll have to replace the trailer. Once I get a galvanized or aluminum trailer I’ll fix issues as needed but for now I’ll just keep on truckin.

 

[FSH 210 Sport]

Alrighty…. After doing the bleeding with a screw driver to pump the actuator rod we were able to get the air out of the system, the air was mainly in the calipers. What did happen while we were bleeding is that the new fluid picked up a ton of contamination that was in the system, so it looked like muddy brake fluid for a while. I recommend that if you are going to do this endeavor you pick up a large bottle of brake fluid and a small one, we used 95% of the large one and I’ve still got the small bottle sealed up to put in my spares crate. Brake fluid has an affinity to attract water

This is why you get the big bottle of brake fluid… there was so much crap in the lines and calipers. Usually when brake fluid turns dark its because it has water in it, which of course leads to corrosion on the inside and that is usually why you loose a caliper seal. That fluid in the bottle was much darker, like black, but the color faded as new clear fluid was added during the bleeding process.



One of the things you will find when bleeding these brakes is that there is an initial dead zone or hysteresis built into the stroke, you can see some fluid pumping from the back to the front along the top Inside the brake fluid reservoir, once the air is out of the system, as soon as that fluid flow stops after about 1/2” of stroke then at the same time the actuator rod stops moving as the brake pads have been applied. I have no idea why it works that way but it does. And the best part is that now I have trailer brakes again.

@Babin Farms my friend who has a boat and trailer he bought in 2005 has the same thing happen to him, the brake fluid just vanishes with no trace as to where it is going.. just one of life’s many mysteries..

So to wrap all this up, there was a good sized high spot on the drivers side brake rotor that I got machined off, O’reily turns brake rotors if you are looking to get that done. It was at that time when I discovered that the brake fluid reservoir was bone dry, this was about 5-6 weeks ago I think. I have been on the road quite a bit since then and had ordered the new actuator some time ago but it came between road trips, Missoula, Birmingham, and lastly St. Anthony, roughly 6000 miles in 4 weeks of driving. I’m glad that the replacement actuator is finally done, and hopefully I won’t need the boat trailer brakes for any panic stops!

Epilogue;

Brake fluid is one of the most overlooked maintenance items on vehicles with hydraulic brakes. When your car was new, your brake fluid reservoir looked almost clear, but over time it has grown dark, and this is due to water assimilating into the fluid, its hypergolic, like the ethanol thats in gasoline, and its really bad for your brake system components, but more so the performance of the brake fluid itself. For the purpose of this short blurb, water contamination or wet boiling point in DOT 3 brake fluid is 3.75%, and look what an impact it has on the boiling point.



So if your brake fluid is ”wet” and you are driving in the mountains, or just a lot of stop and go traffic, there is a good chance you could experience brake fade, which is caused by the fluid boiling and becoming a gas, then you have basically no braking power as there is a big air bubble in your caliper.

 

[FSH 210 Sport]

Follow up…

Pretty nice to have the trailer brakes working again!

There’s also way less movement in the hitch when taking off after a start. When I put everything back together I tightened the swing pivot bolts up pretty snug and removing that little bit of play took away some movement/ vibration and made towing smoother, especially under braking.

 

[AZMark]

Obviously too late now but I was able to find a few videos online of people taking these apart to get an idea of how it all worked. Just had to google various terms about “A-60 brake actuator” to find things.

Those round spacers were pissing me off too. I was able to get it back together while still installed in the trailer but it took a number of tries. Dowels are a great idea.

I need to do the brake fluid flush on my truck and my trailer. This is a good reminder!

 

[bubbasuwannee]

Well, now I've gotta take a look at mine. I'm not really familiar with different types of trailer brake setups and it sucks there's no shop manual for these brakes. I do a ton of car work, so I'm sure I can figure them out.

Thanks for the write up of your experience working on these!

 

[FSH 210 Sport]

Well, now I've gotta take a look at mine. I'm not really familiar with different types of trailer brake setups and it sucks there's no shop manual for these brakes. I do a ton of car work, so I'm sure I can figure them out.

Thanks for the write up of your experience working on these!

Hopefully you still have fluid in the reservoir… if you do its just a matter of looking at the owners manual that came with it on how to bleed it…since you work on cars and stuff you will probably be able to figure it out. There is a small hole on the bottom where you put a screw driver through to get at the actuator rod to manually pump it. There is also this clip like thing that hangs down to release the actuator rod assembly after you have compressed it, this is part of the brake away system. When the brake away system gets actuated by the cable being pulled, it compresses the actuator rod and that clip mechanism holds it compressed to keep the brakes applied.

 

[FSH 210 Sport]

Obviously too late now but I was able to find a few videos online of people taking these apart to get an idea of how it all worked. Just had to google various terms about “A-60 brake actuator” to find things.

Those round spacers were pissing me off too. I was able to get it back together while still installed in the trailer but it took a number of tries. Dowels are a great idea.

I need to do the brake fluid flush on my truck and my trailer. This is a good reminder!

I had forgot all about Google U… I had seen the one vid from Dexter on this site about the guy bleeding the brakes manually by pumping the actuator rod, but even that doesn‘t show much really. Again, now much would it really take to toss in a couple of wooden dowels to hold things in place?? A first world problem, but frustrating none the less. But, now I know how to work on this thing and you can bet I will be keeping an eye on the fluid level.

I raced motorcycles off road for decades, as well as shifter karts for about 6 years, both of those have relatively small brakes / brake components and they are expected to perform one heck of a lot of work. So keeping clean dry brake fluid those braking systems was important… I used to bleed those systems with a 60CC irrigation syringe and push the fluid from the caliper back to the master reservoir, but, you have to flush them out from the master to the caliper first to get all the crap out, otherwise you risk messing up the master cylinder. I remember when I was younger there were power bleeders that were a pot of brake fluid with a connector that went onto the caliper or brake cylinder bleeder that wouldn’t leak and compressed air was put into this pot for pressurization. The brake fluid was then pushed back to the master cylinder from the back, they worked great and made it so one guy could bleed brakes pretty easily. At some point this summer I’ll get my friend to help me bleed the brakes on my truck as well just for good measure, I’ve got those brakes pretty hot a few times, had to have the rotors turned once already and will probably replace the factory rotors and pads with some aftermarket ones down the road. I did that with my last truck and those rotors and pads were nothing short of awesome.

 

[scokill]

Hopefully you still have fluid in the reservoir… if you do its just a matter of looking at the owners manual that came with it on how to bleed it…since you work on cars and stuff you will probably be able to figure it out. There is a small hole on the bottom where you put a screw driver through to get at the actuator rod to manually pump it. There is also this clip like thing that hangs down to release the actuator rod assembly after you have compressed it, this is part of the brake away system. When the brake away system gets actuated by the cable being pulled, it compresses the actuator rod and that clip mechanism holds it compressed to keep the brakes applied.

I just block front and back wheels with chocks and pull back and forth, go back, and hit emergency break. Get out of truck and go turn the bleeder screw. Then repeat as many times as needed. I've done it a couple of times over the years and I'm never prepared for the fluid shooting out the first time.

 

[FSH 210 Sport]

Update:

The other night as I was getting ready to take the boat out the next day I noticed a drop of brake fluid on the ground underneath where the flexible brake line (60”) from the swing tongue meets the long flexible line (200”) that goes down the frame rail. The leak was coming where the red arrow is pointing to.




This leak just showed up on its own, there were no leaks there when we were bleeding the brakes after the new actuator install. I had done one trip of 3 hours round to a lake and back and the brakes appeared to work fine. At the very least, I think this may have been the point at where the oem brake fluid disappeared from.

So the next day I called a local marine shop that is a shoreland’r dealer and I had the part number for them but they would have to order it, next I tried another brake shop who it was said could make the line, I had to leave a message. That guy called back within a half hour with instructions to call another shop in town, he even gave me the part number for the 3/16” line and 3/8”x24 fitting- HF-16. When I called the other shop a gal answered and knew who I was and said she could make the line in 5 mins, and she wasn’t fibbing. The 5 min line was cheaper than the oem one listed in the online parts fische.



The fitting is a different style and I’m good with that. On to bleeding the brakes again. Without giving a total blow by blow, I will just say it took filling a water bottle with brake fluid to get all the air out of the system, so buy a large bottle of brake fluid to do the bleeding with, I also bought a smaller bottle to keep in my spares crate that is sealed just in case I need to add some on the road. Once you start bleeding the system you are going to get a lot of crappy fluid coming out and you should bleed the brakes until the fluid is totally clean and looks like what is coming out of the bottle.



By the way, if you ever want to test your brakes before travel using this manual actuation feature would be the best way to check. One of the things I don’t like about surge brakes is not being able to test them while underway or be able to apply them should a trailer swaying condition happen.

The stroking during the bleeding process will feel inconsistent until all the air is removed, one time you may feel a big one so to speak, and that is usually when some air will come out, the rest will be smaller ones where the actuator doesn’t seem to want to fully compress, thats the way my friends 27 year old son described it, I was laying under the trailer doing the less desirable part of this job. Keep going from side to side bleeding the air out. I started at the caliper farthest away, port, then to the starboard side, then back to port, probably did that 6 times before the stroke of the actuator was consistent and no more air came out. The majority of the air came out all at once, but subsequent bleeding garnered more air bubbles. I

By the way, don’t waste your time with a vacuum bleeder, this system doesn’t work with that type of bleeding and just pulls air into the system due to, IMO, the way the initial part of the actuator works. During the initial part of the stroke, the fluid comes back into the reservoir from the master cylinder, this hysteresis I think could be a way to keep the master cylinder free from air, dunno, but seems like the only plausible reason, see my Mycroft Holmes quote in my signature.

So now I’m looking forward to towing the boat with what I know is a air free system.

I also agree with my friend that such a large amount of flexible brake line reduces effectiveness due to the expanding of the flexible line, so, perhaps over next winter I may remove the 200” flex line as well as the axle cross over flex line and replace them with solid tubing to limit the amount of flex lines in the system and enhance trailer braking.

This one of those issues that sort of nickel and dimed me money wise, but more so time wise and cost me an outing, the money gets replaced but the time and the fishing trip with my friends son are not replaceable. I gained experience and this will be part of my routine checks. Do yourself a favor and check your system over and take a hour or so to bleed your brakes thoroughly and make sure your surge brake system is working properly.

 

[AZMark]

Update:

The other night as I was getting ready to take the boat out the next day I noticed a drop of brake fluid on the ground underneath where the flexible brake line (60”) from the swing tongue meets the long flexible line (200”) that goes down the frame rail. The leak was coming where the red arrow is pointing to.

View attachment 202560
View attachment 202561

This leak just showed up on its own, there were no leaks there when we were bleeding the brakes after the new actuator install. I had done one trip of 3 hours round to a lake and back and the brakes appeared to work fine. At the very least, I think this may have been the point at where the oem brake fluid disappeared from.

So the next day I called a local marine shop that is a shoreland’r dealer and I had the part number for them but they would have to order it, next I tried another brake shop who it was said could make the line, I had to leave a message. That guy called back within a half hour with instructions to call another shop in town, he even gave me the part number for the 3/16” line and 3/8”x24 fitting- HF-16. When I called the other shop a gal answered and knew who I was and said she could make the line in 5 mins, and she wasn’t fibbing. The 5 min line was cheaper than the oem one listed in the online parts fische.

View attachment 202568

The fitting is a different style and I’m good with that. On to bleeding the brakes again. Without giving a total blow by blow, I will just say it took filling a water bottle with brake fluid to get all the air out of the system, so buy a large bottle of brake fluid to do the bleeding with, I also bought a smaller bottle to keep in my spares crate that is sealed just in case I need to add some on the road. Once you start bleeding the system you are going to get a lot of crappy fluid coming out and you should bleed the brakes until the fluid is totally clean and looks like what is coming out of the bottle.

View attachment 202569

By the way, if you ever want to test your brakes before travel using this manual actuation feature would be the best way to check. One of the things I don’t like about surge brakes is not being able to test them while underway or be able to apply them should a trailer swaying condition happen.

The stroking during the bleeding process will feel inconsistent until all the air is removed, one time you may feel a big one so to speak, and that is usually when some air will come out, the rest will be smaller ones where the actuator doesn’t seem to want to fully compress, thats the way my friends 27 year old son described it, I was laying under the trailer doing the less desirable part of this job. Keep going from side to side bleeding the air out. I started at the caliper farthest away, port, then to the starboard side, then back to port, probably did that 6 times before the stroke of the actuator was consistent and no more air came out. The majority of the air came out all at once, but subsequent bleeding garnered more air bubbles. I

By the way, don’t waste your time with a vacuum bleeder, this system doesn’t work with that type of bleeding and just pulls air into the system due to, IMO, the way the initial part of the actuator works. During the initial part of the stroke, the fluid comes back into the reservoir from the master cylinder, this hysteresis I think could be a way to keep the master cylinder free from air, dunno, but seems like the only plausible reason, see my Mycroft Holmes quote in my signature.

So now I’m looking forward to towing the boat with what I know is a air free system.

I also agree with my friend that such a large amount of flexible brake line reduces effectiveness due to the expanding of the flexible line, so, perhaps over next winter I may remove the 200” flex line as well as the axle cross over flex line and replace them with solid tubing to limit the amount of flex lines in the system and enhance trailer braking.

This one of those issues that sort of nickel and dimed me money wise, but more so time wise and cost me an outing, the money gets replaced but the time and the fishing trip with my friends son are not replaceable. I gained experience and this will be part of my routine checks. Do yourself a favor and check your system over and take a hour or so to bleed your brakes thoroughly and make sure your surge brake system is working properly.

I have replaced the flex lines on a truck before and it dramatically firmed up the pedal and reduced the stroke. That might not be ideal on something as imprecise as surge brakes. I could see little jolts locking up the brakes constantly.

I don’t know if this is an issue but it’s something to think about.

 

[bubbasuwannee]

Checked my fluid yesterday and it was full after 2 years of use.

 

[FSH 210 Sport]

I have replaced the flex lines on a truck before and it dramatically firmed up the pedal and reduced the stroke. That might not be ideal on something as imprecise as surge brakes. I could see little jolts locking up the brakes constantly.

I don’t know if this is an issue but it’s something to think about.

Well, as I mentioned, the first part of the stroke doesn’t apply the brakes, that bit o hysteresis maybe there for that dunno. But you make an excellent point.

This drama could have been avoided, well maybe, had I been checking the fluid level regularly. I think the leak on the line was where the fluid went to, I just don’t know if that started after the panic stop two years ago to avoid the huge mule deer doe did something to the line. And the hopping that happened was I’m sure due to that major high spot on the drivers side rotor. All in all hopefully I’m done with working in that for the season and a few thousands of miles of trailering this summer !

 

[FSH 210 Sport]

Checked my fluid yesterday and it was full after 2 years of use.

Is the fluid in the reservoir still clear?

 

[bubbasuwannee]

Is the fluid in the reservoir still clear?

It sure was. maybe a slight yellow tint, but definitely clear.

 

[FSH 210 Sport]

Thats great news!

 

[AZMark]

Well, as I mentioned, the first part of the stroke doesn’t apply the brakes, that bit o hysteresis maybe there for that dunno. But you make an excellent point.

This drama could have been avoided, well maybe, had I been checking the fluid level regularly. I think the leak on the line was where the fluid went to, I just don’t know if that started after the panic stop two years ago to avoid the huge mule deer doe did something to the line. And the hopping that happened was I’m sure due to that major high spot on the drivers side rotor. All in all hopefully I’m done with working in that for the season and a few thousands of miles of trailering this summer !

Sucks you had to do so much work on a fairly new trailer. At least you know it’s all safe now.

 

[FSH 210 Sport]

Sucks you had to do so much work on a fairly new trailer. At least you know it’s all safe now.

Agreed… I do think that leaky line is the root cause. Hey, as long as it is all good and trouble free this will be in the rear view mirror.