# Sticky trailer brake



## Morning Wood (Jan 12, 2008)

So, supposed to tow a boat from Maine to Mass sunday. Just got trailer back from shop. Fixed a broken brake line. Brakes are working but one side is sticking. Just read a bunch of stuff on the net that said it could be anything. Calipers and pads are pretty new. No miles. I'm thinking lubricating the slides are hopefully going to be the answer. Could also be air in system still but they did bleed the lines. I'm going to tackle this in the morning but don't want to spend a lot of time f'ing with this thing. I've don't that before. Worst case scenario I'll get the Caliper free and lock the brakes out so I can drive the thing home. It's not very heavy. Any other suggestions appreciated.


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## Mort (Jul 18, 2012)

Lubricate the slides, sand any rust off of anything that mates or slides. Some shops won't do that, takes too much time for their bottom line. 

BTW, I don't think I've ever heard of a trailer with disc brakes. Am I out of the loop or is this a new thing?


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## tjbnwi (Feb 24, 2009)

Air in the line will not cause the caliper to hang up. As mentioned, clean and lube sliding parts. If that does not cure the issue the piston is not retracting properly. 

Tom


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## tgeb (Feb 9, 2006)

I agree with the clean and lube process.

If that doesn't fix it the piston may be sticking.

Like you I'd get it free, then lock out the system and roll on.

I just had 3 out of 4 wheels that had busted return springs that were dragging, but those were electric drum brakes.


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## Morning Wood (Jan 12, 2008)

It is a boat trailer with hydraulic surge brakes on one axle (tandem). I bled brakes some more. Loosened everything up as best as possible. F'ing Tie Down retrofit design, you have to remove backing plates in order to remove calipers and shoes from the rotor. So I just backed out the slides as much as possible and greased them and pried the pads back away from rotors. Got everything loose and applied brakes. The dam things wouldn't retract again. Pretty sure caliper is shot. The rubber seal doesn't look good. So loosened again and stuck a couple bolts in the coupler so everything is locked out. I'll deal with I when I get home boat and trailer are under 5k lbs.


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## tgeb (Feb 9, 2006)

I saw this boat pull into the lot yesterday.
Considering his set up, I'd bet you'll be fine.


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## Morning Wood (Jan 12, 2008)

To complicate this situation I just read that drum brake actuators should not be used on disc brakes which this trailer now has. (Drum originally). Great. WTF.


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## tjbnwi (Feb 24, 2009)

Morning Wood said:


> To complicate this situation I just read that drum brake actuators should not be used on disc brakes which this trailer now has. (Drum originally). Great. WTF.


Remove the line at the master cylinder, remove the seat, remove the residual check valve and spring, reinstall the seat. The purpose of the valve is to keep enough pressure in the system to keep the cup seals against the cylinder walls. It is a bad thing with disc brakes. 

If the piston boot is shot the piston is probably pitted. 

Tom


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## Morning Wood (Jan 12, 2008)

You mean the caliper piston boot right?


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## tjbnwi (Feb 24, 2009)

Morning Wood said:


> You mean the caliper piston boot right?


Yes. The boot you see is there to keep debris out of the caliper. The square cut piston seal is farther down in the bore.

Reading your posts, it is the residual check valve that is causing the problem you are having.

Tom


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## Morning Wood (Jan 12, 2008)

Again, The one in the actuator by the tongue right?


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## tjbnwi (Feb 24, 2009)

Morning Wood said:


> It is a boat trailer with hydraulic surge brakes on one axle (tandem). I bled brakes some more. Loosened everything up as best as possible. F'ing Tie Down retrofit design, you have to remove backing plates in order to remove calipers and shoes from the rotor. So I just backed out the slides as much as possible and greased them and pried the pads back away from rotors. Got everything loose and applied brakes. The dam things wouldn't retract again. * Pretty sure caliper is shot. The rubber seal doesn't look good. So loosened again and stuck a couple bolts in the coupler so everything is locked out*. I'll deal with I when I get home boat and trailer are under 5k lbs.





Morning Wood said:


> You mean the caliper piston boot right?





Morning Wood said:


> To complicate this situation I just read that drum brake actuators should not be used on disc brakes which this trailer now has. (Drum originally). Great. WTF.





Morning Wood said:


> Again, The one in the actuator by the tongue right?


I'm going to guess at your last question using your posts as guidance.

What I made bold in the first post and your second question is what led me to believe you were referring to the caliper piston boot. After reading it again and with the last post it appears as if you mean the master cylinder piston rod boot. The master cylinder is the part on the tongue. If you are asking about the mater cylinder boot you should change it to keep the bore clean. Master cylinder boot being torn should not cause your problem. 

Here is a link to a drawing showing the location of the check valves. You remove the line from the master cylinder, carefully remove the line seat with a pick, remove the valve and spring, reinstall the seat, install the line loosely, fill the master cylinder, when fluid runs out between the line and the master cylinder tighten the line. You should not have to bleed the brakes again because the line is higher than the calipers, fluid should have stayed in the line. 

If you do not want to go through removing the valve you'll have to locate the same size and mounting type master cylinder for disk brakes.

http://www.jalopyjournal.com/forum/threads/master-cylinder-residual-valve.433296/

Tom


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## Morning Wood (Jan 12, 2008)

Thanks Tom. Very helpful. I'll tear into intros weekend and see if the check calve is still in there.


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## Morning Wood (Jan 12, 2008)

*Sticky Trailer Brake*

Ok. Here is what I've got. Which side of the fluid reservoir should I be looking at for that check valve?

Also, is that a tiny shock absorber underneath the tongue? If so, it's completely shot. Thanks, Nick.


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## Morning Wood (Jan 12, 2008)

Forgot pics.


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## Morning Wood (Jan 12, 2008)

Ok. I finally pulled my head out of my ass. I have this thing figured out. I'm waiting on some snap ring pliers so I can check this out. Hopefully the spring and limiter are in there and I can remove them and these brakes will improve.


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## tjbnwi (Feb 24, 2009)

Discharge side.

The shock is a damper to keep the brakes from coming on to strong. 

Check to see what an assembly will cost you. May be easier than rebuilding everything.

Tom


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## Morning Wood (Jan 12, 2008)

Damper was only $26 or so.
If there is a spring in there and a check valve I'll get it. Should be just like this I hope.

https://www.etrailer.com/question-61178.html


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## Morning Wood (Jan 12, 2008)

It was in there. Now lube the calipers and bleed brake lines again. We'll see how she does.


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## tjbnwi (Feb 24, 2009)

If you have a hand vacuum pump that is the best and easiest way to bleed the brakes. Mighty Vac makes a pump kit with the necessary pieces.

If the lines did not drain you only need to bleed at the master cylinder.

Tom


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## Morning Wood (Jan 12, 2008)

All ordered up. Boat is splashing in tomorrow and I'll have the trailer free and clear to f with over the weekend


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## Morning Wood (Jan 12, 2008)

Was able to pull a caliper today as I have the week off due to child care issues. I think the calipers are shot. I couldn't get enough play in the calipers to remove the pads. So, I think the piston is frozen and won't return. I'm not surprised seeing as they have never been allowed to return with that check valve in the master cylinder. Probably just get new calipers and swap them out and bleed them again and see what happens this time around.


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## tjbnwi (Feb 24, 2009)

Morning Wood said:


> Was able to pull a caliper today as I have the week off due to child care issues. I think the calipers are shot. I couldn't get enough play in the calipers to remove the pads. So, I think the piston is frozen and won't return. I'm not surprised seeing as they have never been allowed to return with that check valve in the master cylinder. Probably just get new calipers and swap them out and bleed them again and see what happens this time around.


Loosen the bleeder and see if they'll retract. I have seen the hoses delaminate, when you attempt to park the piston the lamination seals the hose and locks the piston.

Tom


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## Morning Wood (Jan 12, 2008)

won't that suck air back into the line?
I believe the hoses are only a couple years old.


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## tjbnwi (Feb 24, 2009)

No, the hoses are multi ply.

Tom


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## Morning Wood (Jan 12, 2008)

Ok. So not my idea. My father thinks that taking the calipers off the trailer for short distance towing is the way to go. Most likely the long distance only happens twice a year. Otherwise it's a few miles to ramp which kills the brakes. Is there a way to plug the brake lines if the calipers were removed? Is the fitting at the calipers a flare fitting? 

http://www.easternmarine.com/tie-down-g-5-caliper-assembly-w-pads-46910a

Thanks, Nick.


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## tjbnwi (Feb 24, 2009)

Flex hoses have banjo fittings with banjo bolts, no flare.

Tom


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## Morning Wood (Jan 12, 2008)

Damn. I knew that.


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## tgeb (Feb 9, 2006)

I would not disable the brakes. 
In the event there may be an indecent, and it was investigated, you would likely be found at fault, and that could cost you a whole lot more than a couple hundred bucks that it would take to buy and install the new calipers. 

I know you already know this.


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## Morning Wood (Jan 12, 2008)

It wouldn't matter. Locally with brakes off the trailer the commute is about 1 mile at 25 mph. The boat and trailer are quite light. When used for going between ma and me then the brakes would be on and hopefully would function correctly


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## Morning Wood (Jan 12, 2008)

Ok. Tom you seem pretty knowledgable with this stuff. So we installed new calipers and pads. Got everything installed and I went to bleed he brakes with the mightyvac. The thing just sucked air forever. Couldn't get any fluid really to come out. So we pumped the tongue to activate the master cylinder and fluid did come out fine. No bubbles. The mightvac I tried on my thumb and it held pressure fine. No leaks in the syatem that I can see, but after road test and trying mightvac again still didn't get any fluid from it. Just cracked the bleeder and didn't open it alot. But, got both calipers as far as I can tell bled by pumping the tongue. 
Is there some type of way to do it with brand new calipers or something? I'm pretty fed up with this f'ing trailer. Glad it is going away soon. Thanks, nick.


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