Why Are My Brakes Suddenly Locking Up?

[lncoop]

Re: Why Are My Brakes Suddenly Locking Up?

Allrighty. I'm not certain, but I think I've cracked it. I put the coupler back on this morning and bled the driver side with no trouble. When I attempted to bleed the curb side I pushed against the plunger so hard the shaft of my screwdriver was bending, but there was barely a dribble coming from the bleeder. At that point I began systematically disconnecting one fitting at a time starting at the MC and pushing fluid. After I flushed the last point I jacked her up and noted satisfactory performance, so I took her for a test drive. Once I returned I jacked her up again and the wheels were dragging slightly. I adjusted the curb side, but the star on the driver side adjuster won't turn a click, even after being introduced to penetrating oil, big channelocks, and a hammer, so I pulled it to take to the trailer parts store Monday. I'll probably also go ahead and replace the shock absorber while I'm at it. I can slide it by hand, but it doesn't seem to be a hundred percent. Once I get that done I'll test her out and report. Thanks for the input everyone.

 

[lncoop]

Re: Why Are My Brakes Suddenly Locking Up?

UNCLE!!!!! After that^^^ they still weren't functioning properly. I've replaced both rubber lines and the faulty adjuster and flushed and bled til I'm blue in the face. Here's where I am now. If I actuate them manually with a big screwdriver against the plunger they stop then release properly, but after I tow the trailer around the neighborhood then jack it up when I return they're almost completely locked up every time. I just had my buddy drive around the neighborhood while I sat in the back of the Expedition with the lift gate up and I watched the coupler slide forward when braking then slide back just as I think it should. I just don't know what to think at this point. Unless someone has an epiphany for me I'm going to have to throw in the the towel and take it to the shop. I hate to do it, but I'm completely stumped.

 

[tswiczko]

Re: Why Are My Brakes Suddenly Locking Up?

Sorry Coop No epiphany's here for ya brother,

I'm trying to think of all the things that I have done wrong that has caused this problem.

Lets see, I done done a brake job on my old Grenada years ago and got the adjusters switched (left to right 0 and they would run the shoes out every time I hit the brakes, after 3 or 4 stops they would stay locked up.:facepalm:

On my old ford I had the primary and secondary shoes reversed and they would lock up spontaneously at times. (now I never forget the little shoe goes to the front).:facepalm: After pulling them apart 3 or 4 times I put them back together the the picture in the book looked.:redface: now I don't take more than one wheel at a time to avoid confusion and so I can reference the other side if anything looks amiss

What does it look like under the drum, a single servo wheel cylinder that (only actuates one shoe)?
Did you replace any hardware last year(or not) when you done them like maybe the spring on the shoes that could possibly be weak.

Sorry I can't give you any other Ideas to help get you rolling.

 

[bruceb58]

Re: Why Are My Brakes Suddenly Locking Up?

Take a picture of one of the assembles and note if its the right or left and post it up here.

 

[lncoop]

Re: Why Are My Brakes Suddenly Locking Up?

This is the right (passenger) side. Note the stowaway on top. Maybe he's been locking them up. When I jacked it up to remove the hub it spun freely, so obviously they released on their own some time between yesterday and now. Ay carramba!:facepalm:

 

[UncleWillie]

Re: Why Are My Brakes Suddenly Locking Up?

As long as you have it off ...

Have someone operate the coupler manually.
Note how the brake cylinder extends.
See if it retracts as soon as the pressure is released.
I would be hesitant to trip the breakaway actuator without the drum on.
It could over extend the brake cylinder, and pop the piston completely out.

With the luck you have been having so far... I would not be surprise if that Beetle's name isn't "Murphy."
In which, case you will be subject to his Law!

 

[lncoop]

Re: Why Are My Brakes Suddenly Locking Up?

With the luck you have been having so far... I would not be surprise if that Beetle's name isn't "Murphy."
In which, case you will be subject to his Law!

I knew I should have killed that little rascal when I had a chance.

 

[bruceb58]

Re: Why Are My Brakes Suddenly Locking Up?

That looks perfect to me.

 

[CatTwentyTwo]

Re: Why Are My Brakes Suddenly Locking Up?

As long as you have it off ...

Have someone operate the coupler manually.
Note how the brake cylinder extends.
See if it retracts as soon as the pressure is released.

I would definitely try this. When I had drum brakes and had a problem, it was always the wheel cylinders. They get moisture and corrosion behind the rubber boot and then hydraulic pressure can push the piston out but the springs are not strong enough to pull it back. Have you tried cracking the bleed screw open again when they are locked up? That might help to narrow it down also.

 

[lncoop]

Re: Why Are My Brakes Suddenly Locking Up?

Had the admiral actuate the brakes earlier while I watched the cylinder. Everything appeared to function properly. The aduster fell out, but I gather that's normal when the wheel's not on since it's never happened before. If not, someone please let me know. As I mentioned earlier, they only lock up after I've towed it, not when I test it in the driveway. And, they released some time after yesterday afternoon's test tow. When I jacked it up this afternoon the wheel that was off the ground was spinning freely, so obviously there is fluid return. Did I mention I'm stumped?

 

[UncleWillie]

Re: Why Are My Brakes Suddenly Locking Up?

...The aduster fell out ...

Interesting!!



Consider this possibility...

When the brakes are applied ...
Piston 1 pushes Shoe 2 against the Drum and down against adjuster 3.
Adjuster 3 pushes Shoe 4 against the Drum and up against (un-numbered) pin above brake cylinder.
So far so good!

When brakes are released....
Spring 5 retracts Shoe 2 and Piston 1.
Springs 6 and 7 retract adjuster 3 and Shoe 4.
Spring 8 keeps the top of Shoe 4 tight against the top pin.
As it should.

If Shoe 4 does NOT return via spring 7, spring 6 will retract adjuster 3.
And the left side of Adjuster 3 will fall out of shoe 4!
Shoe 4 will remain in contact with the Drum and the brakes will not release.

And then Murphy arrives ....

 

[gus-gus]

Re: Why Are My Brakes Suddenly Locking Up?

The picture is a breed of brake I have not seen. No idea.

 

[bruceb58]

Re: Why Are My Brakes Suddenly Locking Up?

Willie, The adjuster fell out becuase he didn't have the drum on.

 

[Idlespeedonly]

Re: Why Are My Brakes Suddenly Locking Up?

That is a Demco free backing type. The adjuster should be turned around. It shouldnt make any difference though. I would check the wheel cylinder for corrosion if you havent already done so.

 

[lncoop]

Re: Why Are My Brakes Suddenly Locking Up?

That is a Demco free backing type. The adjuster should be turned around. It shouldnt make any difference though. I would check the wheel cylinder for corrosion if you havent already done so.

That's factory orientation for the adjuster. If it were turned around the star thingie (technical term) wouldn't be accessible. Wheel cylinders are less than a year old. I haven't seen the other one in action, but the exposed one seems to be functioning properly, so I'm pretty confident it's not them.

 

[bruceb58]

Re: Why Are My Brakes Suddenly Locking Up?

The adjuster is in the correct orientation.

Looks like the same one as here:
http://www.etrailer.com/Trailer-Brakes/Titan/T4423400.html

 

[UncleWillie]

Re: Why Are My Brakes Suddenly Locking Up?

Willie, The adjuster fell out because he didn't have the drum on.

I realized the drum was off.

I am thinking that the spring(#7) above the a adjuster keeps the tension between the two brake shoes, and the adjuster maybe-shouldn't have fallen out if the shoes are able to reposition themselves easily.
If the Brake piston was retracting, and the shoes were retracting freely via the springs, He would not be having a problem.
We are looking right at the problem somewhere in the picture!

We are grasping at straws here. Anything/everything is suspect.
Let?s not rule out anything arbitrarily! We have to try something!

A Judicious touch of grease on the back plate where the shoes slide, and under the cups on the "Nails" that hold the shoes against the back plate may be in order.
That would rule out this scenario.

As a minimum; It would be justified to disassemble the brakes shoes and re-inspect for any binding.

 

[Cheetah 210es]

Re: Why Are My Brakes Suddenly Locking Up?

Any kinks or pinches in the metal lines? I've seen a couple similar where the line had been nipped either by running over something that flipped up or by bad positioning of the jack. The brakes work because of the higher pressure but wont release because its only spring tension pulling them back in. Hope this helps.

 

[lncoop]

Re: Why Are My Brakes Suddenly Locking Up?

The unique free-backing design, patented by DICO, lets your trailer move in reverse without actuating the brakes. When you begin backing up, the brake shoes are firm against the drum, as in a braking situation. As you continue in reverse, however, the shoes turn with the drum until the lining pressure is released and you are able to back up freely(my italics)

Okay, bear with me guys. Just for giggles I clicked on the link Bruce provided and stumbled onto this little tidbit. If my interpretation is correct, even though my assemblies are free-backing, it is normal for the brakes to act as if they are engaged when backing the trailer and the shoes gradually pull away from the drum as the backing continues. Every examiniation I've performed has been immediately following my backing the boat back into the driveway, which is a pretty quick process because I've done it so many times, and the last maneuver is a fairly sharp turn to get her lined up just right. What if the brakes have been working right the entire time and I just thought there was a problem because of my lack of knowledge? This diagnosis would be consistent with what I've been experiencing. When towing the trailer around the neighborhood there are no symptoms typically associated with grabbing brakes. When I've tested them immediately following backing the trailer into the driveway they've been grabbing, but not at any other time.

I think I'll take the rig to a big parking lot and engage the brakes abruptly while driving around then jack up the trailer and spin the wheels, then assuming they're not grabbing I'll back the trailer a long distance and jack it up again. If they're not grabbing then we'll have our answer. If they are, once I pick myself up from the ground following my kicking and screaming tantrum I'll take it to the trailer shop. :facepalm:

 

[UncleWillie]

Re: Why Are My Brakes Suddenly Locking Up?

The adjuster is in the correct orientation.

Looks like the same one as here:
http://www.etrailer.com/Trailer-Brakes/Titan/T4423400.html

Zoom In on the third thumbnail!

No way the adjuster should fall out!