Trailer bleeding brakes. Part 2

ESGWheel said:

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Your image was what I wanted to do. It would match the longer hose running to the port side as it is on top of the axle with zip ties and snakes down into the caliper. I always felt that this hose hanging down would catch something on the road but at the time it was installed, I did not know anything about it to ask.

And you were on point with the roller coaster loop. That is what I though it needed and it was installed that way. I felt with the loop and the trailers down time it would create an issue with fluid just setting at the bottom.

Now that I kinda know what I am doing, it should not be an issue anymore. Also even using that bleeder, I will still go to the actuator and give it a few pumps as when I tried to bleed it before.

Image is of the port side. I will go and adjust that loop i made on the starboard side and try to run direct with some play or get a degree fitting if its acting up.

Thanks man.

You really want to make sure that as the suspension cycles up & down the brake line won’t get snagged. I have bled brakes with the very simple Lisle one man brake bleeder kit with no problems and while my trailer has drum brakes I have also used this on disc brake vehicles as well. I’m wondering if you have air trapped in your master cyl or there’s a leak in a brake line you can’t easily see…

demarko210 said:

Image is of the port side. I will go and adjust that loop i made on the starboard side and try to run direct with some play or get a degree fitting if its acting up.

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Good you are doing it this way vs going over the frame. This is the proper way.

I only bleed brakes with a pressure bleeder these days. Not only on cars/trucks, but also use one on the boat trailer I own that still has surge brakes. My other two trailers have electric over hydraulic brakes so those are very simple.

Hopefully, you lubed the slider pins before you installed the caliper on your trailer. Not too late to do if you haven't.

I love disc brakes...1000 times better than drum brakes. I still have drum brakes on that one trailer I mentioned before. Only good thing is that it gets dunked twice a year into a fresh water lake...once when launching in spring and once when retrieving in the fall.

Lou C said:

You really want to make sure that as the suspension cycles up & down the brake line won’t get snagged. I have bled brakes with the very simple Lisle one man brake bleeder kit with no problems and while my trailer has drum brakes I have also used this on disc brake vehicles as well. I’m wondering if you have air trapped in your master cyl or there’s a leak in a brake line you can’t easily see…

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Yes be able to move freely and not affected by the suspension moving up and down.
So with the starboard caliper i finally got it to bleed after pulling the bleeder valve off and cleaning it. But it did not bleed like the port side. Port side I got real good stream. Starboard side it took 10x as long to get the stream into the collection reservoir.
Also when I push the actuator to engage the brakes the port side would release but the starboard side would still be locked and slowly release after a while or if I hit the bleeder to release it.

demarko210 said:

Yes be able to move freely and not affected by the suspension moving up and down.
So with the starboard caliper i finally got it to bleed after pulling the bleeder valve off and cleaning it. But it did not bleed like the port side. Port side I got real good stream. Starboard side it took 10x as long to get the stream into the collection reservoir.
Also when I push the actuator to engage the brakes the port side would release but the starboard side would still be locked and slowly release after a while or if I hit the bleeder to release it.

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You shouldn't even see them release much at all. Don't be too worried if one looks like it releases and the other one doesn't. That's just the anti rattle springs doing that(if equipped). Pads are designed to just float along the rotor. The one that looks like it doesn't release is more than likely just a tighter fit of the seals in that one caliper piston.

Don't turn the bleeder screw to release it. By doing that you just allowed air to enter.

Have someone turn the rotor while another person pulls the break away lever. It should take extremely little movement of the break away bar to lock up the rotor that the one person is turning.

Agreed on the benefits of disc brakes, while I still have drums on my boat trailer it goes in the salt water only 2x per year. If I were a trailer boater and had to dunk the trailer every time I used the boat I'd have converted to discs years ago.
I grew up with both self adjusting and non self adjusting drum brakes on 60s and 70s vehicles and the first time I worked on a vehicle with disc brakes it was like a revelation lol. American cars with self-adjusting rear drums (sort of lol) and '60s VWs with manually adjusted drums. BTW, the light VWs with their rear weight bias stopped just fine with their drums. A relative had a '71 Ford Fairlane with manual drums and that thing was hard to stop. We later had a '71 Fairlane with power front discs and it was much better.

My wife is an expert assistant when it comes to bleeding brakes.
Them vacuum bleeders are ok as long as all the pipework is favourable , hardly ever is .
The biggest advantage of the foot on the pedal bleeding is that any air bubbles are compressed and when the bleed nipple is cracked the pressure of the fluid carries the bubble out the bleed port . And when vacuum bleeding it is possible ( highly likely ) air can be sucked in around the threads of the bleed nipple and will show up as bubbles in the clear bleeder hose making you think its still got air in the system .
Another thing often overlooked is the rear seal on the master cyl if this is faulty it can act like a one way valve and it can suck in air behind the piston as the piston is advanced , and when the piston returns to battery this air is forced past the piston seals and into the fluid .

ESGWheel said:

Sorry for being late to the party but here are a few thoughts for consideration.

• An internally collapsed hose is not a result of the routing unless it was an extremely tight bend or exposed to road damage. It may have simply failed.
• The picture of your hose seems to have too much play and is low to the ground which may have exposed it to road debris damage
• And just to be sure: while the word “loop” is being used it does not mean a literal loop like a roller coaster going upside down. It simply means enough play in the hose to account for the suspension movement + the in/out of the caliper which is critical.
• They make hoses with a 90 bend at the caliper end (link) that you can use to get the hose back to the axle with enough ‘play’ to account for the needed flex. Alternatively, they also make a 90-degree fittings to accomplish the same thing. The key here is to get it to look like the below mockup. And since you have a torsion axle more play than my mockup represents is needed.

I have the same bleeder device you do that creates a vacuum and have used it successfully. However, IMO, nothing beats creating pressure with the actuator (aka master cylinder) and cracking open the bleeder screw. I use the actual trailer hitch ball mount I put in my truck for this. Lock the ball into the actuator as if you were going to tow and now have a lever that can push down on to create the pressure. I have someone do that while I am at the bleeder screws cracking them open. I have them pump up the pressure 2 or 3 times and keep pressing down on the last stroke and then crack open the bleeder no more then a 1/4 of a turn and then close bleeder prior to helper releasing pressure to stroke again. So it’s a quick open/close. Repeat until no air. I use the vacuum device with the hose connected to the bleeder as a collection device as well as being able to see any bubbles in the clear hose. Note: use the closed end of the wrench for this process > just put it on prior to putting on the hose on the bleeder.

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My wife is an expert assistant when it comes to bleeding brakes.
Them vacuum bleeders are ok as long as all the pipework is favourable , hardly ever is .
The biggest advantage of the foot on the pedal bleeding is that any air bubbles are compressed and when the bleed nipple is cracked the pressure of the fluid carries the bubble out the bleed port . And when vacuum bleeding it is possible ( highly likely ) air can be sucked in around the threads of the bleed nipple and will show up as bubbles in the clear bleeder hose making you think its still got air in the system .
Another thing often overlooked is the rear seal on the master cyl if this is faulty it can act like a one way valve and it can suck in air behind the piston as the piston is advanced , and when the piston returns to battery this air is forced past the piston seals and into the fluid .

Mc Tool said:

My wife is an expert assistant when it comes to bleeding brakes.
Them vacuum bleeders are ok as long as all the pipework is favourable , hardly ever is .
The biggest advantage of the foot on the pedal bleeding is that any air bubbles are compressed and when the bleed nipple is cracked the pressure of the fluid carries the bubble out the bleed port . And when vacuum bleeding it is possible ( highly likely ) air can be sucked in around the threads of the bleed nipple and will show up as bubbles in the clear bleeder hose making you think its still got air in the system .
Another thing often overlooked is the rear seal on the master cyl if this is faulty it can act like a one way valve and it can suck in air behind the piston as the piston is advanced , and when the piston returns to battery this air is forced past the piston seals and into the fluid .

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that last point is what I was wondering about, I never had trouble bleeding the brakes on my trailer and the actuator is over 20 years old now, but I guess that can happen.

demarko210 said:

But it did not bleed like the port side. Port side I got real good stream. Starboard side it took 10x as long to get the stream into the collection reservoir.
Also when I push the actuator to engage the brakes the port side would release but the starboard side would still be locked and slowly release after a while or if I hit the bleeder to release it.

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Lots of good info here but I am going to suggest two things still warrant looking at.

1st with respect to bleeding using the vacuum device > follow the same protocol of putting the closed end of the wrench on the bleeder screw prior to hooking up the hose, turn on the vacuum device and only open the screw no more then ¼ turn. As mentioned above air can get sucked in around the bleeder screws threads giving a false indication of air in the line. And by putting the closed end of the wrench on the screw you have better control and a visual of the ¼ turn opening (vs using the open end, having it slip off and then having the hose itself causing the value to open more as screw is real easy to turn (or should be)). And a ¼ turn (or less) should help preclude sucking in air. Sucking air thru the threads of the bleeder screw is not an issue with pressure bleeding.

2nd that stbd side is not ‘releasing’. I strongly recommend further investigation. The piston of a disc brake caliper is retracted by two things: (1) the square “O-Ring” sealing the piston actually flexes when the brakes are applied and once pressure is relieved, it relaxes back to its normal shape pulling in the piston and (2) the play in the wheel bearing allows ever so slight movement of the rotor > a very slight rocking back and forth (as if you grabbed the wheel at top and bottom and push / pulled) > this play also ‘pushes’ on the pad which pushes on the piston (once the pressure is relieved). All that said, a key indicator of something wrong is when one side behaves or feels differently from the other. And this really caught my attention.

More: I am unsure if you changed out the actual hoses, reroute yes, but are they new? The concern is that you had to relieve pressure via the bleeder screw to get it to be free. That, and the issue with 10X the effort to bleed, leads me to believe you have an internally collapsed hose or some other restriction. This restriction is not allowing the pressure to bleed off AND is causing air to be sucked around the threads of the bleeder screw giving a false indication as mentioned above > i.e. the restriction is causing the fluid to not easily flow in either direction.

While the above is my first guess, it’s also possible that the caliper is bad via one of two methods (1) the piston / seals are such that the piston does not operate as it should (ex. corroded piston, damaged seal) or the floater pins/caliper are not freely moving. But this does not account for the 10x to bleed, hence my first guess.

More More: it is my strong opinion that you need to be 100% confident your brakes are working as designed and if need be, take it somewhere to be sure. While not ideal to turn it over to others, I truly get that, but the hazards of not having proper working brakes on trailer or the tow vehicle are simply not worth it.

I test them in a big quiet shopping mall with another person driving and doing different degrees of stopping. As I watch the wheels.

Another thing that can cause issues , gotta admit I have not seen this on a braked trailer but it goes with the above ESGWheel info .
When the brake is applied the master cylinder piston must advance far enough to close the port to the fluid reservoir before any pressure is applied to the system . This is seen as free play at the pedal or lever ( cars or bikes ) and I have seen peeps adjust things in an attempt to reduce this free play by advancing the piston until that port is unwittingly covered . But with the port covered / blocked as the fluid heats up its got nowhere to go other than moving the caliper piston and the brakes start to apply , and as the brakes heat up the pressure increases and it snowballs from there to locked wheel city . A perverse twist to this is that by the time you have got home from hospital the whole thing will have cooled down and the fault may not be evident ( nah not me , it was Brian but I was right behind him when he chucked down the road yeah that was real funny and I tried to tell him but ...)

Lou C said:

We later had a '71 Fairlane with power front discs and it was much better.

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Old friend of my brother had a Montclair with powerbrakes. Oh my gosh with a slight tap of the brake you almost hit your head on the dashboard. I could not drive that car 2 blocks. Take some getting use too.

ESGWheel said:

2nd that stbd side is not ‘releasing’. I strongly recommend further investigation.

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I purchase new calipers and a new 24" hose. The old calipers I will rebuild and place on my other single axle boat trailer that is in its project stage. The old one I removed the piston and rubber seals. No pitting and the seals are in good shape except for when I removed the main seal. I think the issue was just the 24" hose. I will let you guys know when I test drive it to pick up some lumber.

demarko210 said:

Old friend of my brother had a Montclair with powerbrakes. Oh my gosh with a slight tap of the brake you almost hit your head on the dashboard. I could not drive that car 2 blocks. Take some getting use too.

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Yep the ‘70 with manual drums took 2 feet to stop and the ‘71 with power front discs just took the weight of your foot!

Lou C said:

Yep the ‘70 with manual drums took 2 feet to stop and the ‘71 with power front discs just took the weight of your foot!

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You can stop one of them land yachts in 2 feet ?
Good brakes , how bout 100hp , 185kg ( that 407 pounds for all you imperial Americans ) wet and TWO 320mm discs with 4 pot calipers . Thats more brakes than most 2 ton cars have . ( so how come you rode that motorbike into the back of a car at 100mph I hear you ask

lol a play on words…
I will say that the surge drum brakes on my trailer (12” free backing) stop it really well.

Well there has to be a reason why trucks still use drums , I think the drums give a lot more swept area than discs .

While we are diverging from the OP’s issue, I will take a chance and provide my thoughts regarding Drum vs Disc. My understandings: (1) for a given diameter disc have move sweep area then drum and (2) drums have a mechanical multiplying (aka self-energizing) effect that increases the shoe’s pressure against the drums beyond what the hydraulic pressure is doing > the forward shoe, when rubbing against the drum tries to rotate with it, causing the bottom of that forward shoe to push against the bottom of the rear shoe (via the adjuster), which has also been pushed out to engage the drum causing it to also try to spin with the drum causing the top of the rear shoe to push against the cylinder which in turn causes the forward shoe to press even more against the drum (they are coupled b/c the hyd fluid is not compressible). For disc brakes, the only force pressing the pads against the disc is the hyd pressure. Note that there is a higher pressure applied to disc vs drum due to these design differences. This is why Lou has the experience he does with that 70’s auto and his trailer.

ESGWheel said:

While we are diverging from the OP’s issue, I will take a chance and provide my thoughts regarding Drum vs Disc. My understandings: (1) for a given diameter disc have move sweep area then drum and (2) drums have a mechanical multiplying (aka self-energizing) effect that increases the shoe’s pressure against the drums beyond what the hydraulic pressure is doing > the forward shoe, when rubbing against the drum tries to rotate with it, causing the bottom of that forward shoe to push against the bottom of the rear shoe (via the adjuster), which has also been pushed out to engage the drum causing it to also try to spin with the drum causing the top of the rear shoe to push against the cylinder which in turn causes the forward shoe to press even more against the drum (they are coupled b/c the hyd fluid is not compressible). For disc brakes, the only force pressing the pads against the disc is the hyd pressure. Note that there is a higher pressure applied to disc vs drum due to these design differences. This is why Lou has the experience he does with that 70’s auto and his trailer.

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Might be wrong but I have always thought tis was called (self servo ) and on bikes with TLS (twin leading shoe) brakes it can so strong that the bike will stop on a dime ..... going forward but wont stop it rolling backwards very well . Possibly why rear drums are sls ( single leading shoe ) on cars etc otherwise the handbrake wont work so well backwards ( like park it on a hill ) , but with one leading shoe in each direction your covered