Why Are My Brakes Suddenly Locking Up?

[lncoop]

21' Trailstar single axle trailer with Titan model sixty coupler. Free backing brakes. New master and wheel cylinders last spring. Towed fine all summer, but this evening I moved it out of the back yard to jockey some trailers, and while I had it out I decided to put on the new tires I had gotten in today. I had put one on (curb side) in the back yard, pulled the boat out and parked it on the street, then put it back in the driveway to put on the other tire. When I jacked it up I noticed the driver side wheel would barely turn with considerable effort. The actuator was engaged (plunger in). I loosened the bleed valves and that freed the wheels. Since I had gone that far I went ahead and bled the lines and the fluid that came through looked good; no rust or crud. I took it for a spin around the block and when I returned they were locked up again, but this time the plunger was fully extended. I noticed the emergency lever (the one attached to the breakaway cable) had less play than normal, so I removed the cover and jiggled it and tried to spin the wheel on the side I had jacked up again (curb side) and it spun freely. After I jiggled the lever some more and replaced the cover the wheel would still spin but was dragging quite a bit. I don't see how the lever could cause this since it has quite a bit of play before it starts pushing on the plunger, but I don't know what to think.

 

[dockwrecker]

Gummed up coupler probably. Mine did that too with a d60. Pulled the coupler apart, wire wheeled the rust out and put it back together with lots of anti seize. Also look at the shock inside the coupler and see that it isn't rusted stuck. Good luck Coop!

 

[robert graham]

Re: Why Are My Brakes Suddenly Locking Up?

Are your brakes the self adjusting kind?...maybe adjuster moved too far, locking the brakes? Sounds like you're gonna have to pull those wheels/brakes for closer inspection. Let us know what you find and good luck!

 

[RogersJetboat454]

Re: Why Are My Brakes Suddenly Locking Up?

I'm assuming you have rubber lines from the frame to the wheels. How recently have those been replaced? I have seen it several times on cars where the rubber lines will break down internally, and start acting like a one way valve. You can pressure the brake fluid into the line thus applying the brakes, but when the pressure is released, the restricted fluid will keep the brakes applied and only release if you crack the bleeders or wait long enough for the fluid to seep back to the master. Just food for thought.....

 

[lncoop]

Re: Why Are My Brakes Suddenly Locking Up?

I'm leaning toward Dockwrecker's diagnosis, because messing with the coupler did seem to have an impact, and in retrospect I'm thinking some of what I thought was plunger movement was actually the entire coupler moving. At ten years old and outside its entire life it's certainly not a stretch to suspect the coupler. I checked with my local trailer parts house and they have a shock absorber in stock, so I'll clean the coupler and go ahead and replace the shock absorber while I'm in there. Should be thirty bucks well spent. Thanks guys. I'll report back when I know.

 

[lncoop]

Re: Why Are My Brakes Suddenly Locking Up?

I'm assuming you have rubber lines from the frame to the wheels. How recently have those been replaced? I have seen it several times on cars where the rubber lines will break down internally, and start acting like a one way valve. You can pressure the brake fluid into the line thus applying the brakes, but when the pressure is released, the restricted fluid will keep the brakes applied and only release if you crack the bleeders or wait long enough for the fluid to seep back to the master. Just food for thought.....

Interesting. Maybe I should go ahead and address those while I'm at it. Can't imagine those two short sections would be difficult or expensive to replace. Rogers, here's a question. When I opened the bleeders the fluid shot out like it was still under a lot of pressure. Would that be consistent with internal breakdown in the lines? Seems like it would be more of a dribble, but I don't know.

 

[RogersJetboat454]

Re: Why Are My Brakes Suddenly Locking Up?

Rogers, here's a question. When I opened the bleeders the fluid shot out like it was still under a lot of pressure. Would that be consistent with internal breakdown in the lines? Seems like it would be more of a dribble, but I don't know.

Seen it with my own eyes... on cars mind you. If one came in with dragging brakes the usual problems were frozen calipers/cylinders or a bad line. To test which one, I would open the bleeder. If the fluid shot out and the wheel released, the line was suspect. If the fluid dripped out, and the wheel was still stiff then the caliper/cylinder was most likely frozen.

Then again, cars don't have crusty couplers. If the coupler is maintaining pressure on the system when it should theoretically be released, its going to shoot brake fluid and release the brakes when you open the bleeders. If both sides are having this issue, then chances are high the common denominator that could cause the problem is the coupler. If only one side is doing this, I would suspect the line. Good luck.....

 

[lncoop]

Re: Why Are My Brakes Suddenly Locking Up?

Okay, thanks Rogers. I'll communicate the solution when it avails itself.

 

[bruceb58]

Re: Why Are My Brakes Suddenly Locking Up?

With drum brakes you will always have a small amount of pressure in the lines. There is a residual valve in the master cylinder that causes that. Just mentioning this so it doesn't fool you.

I would pull the drum on the offending side. If you truly had some extra pressure caused by the actuator, I would expect both sides to be locked up. A cause for one side locking up over another would be grease getting past the rear seal coating the brakes. That will make them stick like crazy believe it or not.

 

[lncoop]

Re: Why Are My Brakes Suddenly Locking Up?

Both sides are locking up. That fact was probably not readily apparent from my original post, which was mostly late night rambling after three hours of doing exactly what I swore to myself I wouldn't; messing with the brakes at night in the cold wet weather. I have trouble letting stuff go sometimes.:facepalm:

 

[Thalasso]

Re: Why Are My Brakes Suddenly Locking Up?

Are your brakes the self adjusting kind?...maybe adjuster moved too far, locking the brakes? Sounds like you're gonna have to pull those wheels/brakes for closer inspection. Let us know what you find and good luck!

Free backing brakes don't have self adjusters. I don't think any boat trailer has them.

 

[bruceb58]

Re: Why Are My Brakes Suddenly Locking Up?

I forget what you replaced last year. Did you replace the whole coupler or master cylinder only?

 

[lncoop]

Re: Why Are My Brakes Suddenly Locking Up?

I forget what you replaced last year. Did you replace the whole coupler or master cylinder only?

Master and wheel cylinders. I pulled the coupler this afternoon. I dropped the shock absorber to see how freely the coupler would slide. I was easily able to actuate it. I then put the shock absorber back in place and tried it again. I'm pretty sure it's behaving normally though I don't have anything to compare it to. I'll put the coupler back on tomorrow and see what happens.

 

[scoyt]

Re: Why Are My Brakes Suddenly Locking Up?

If I didn't have to work tomorrow, I would come help ya work on it! Good luck, keep us posted.

 

[Silver Eagle]

Re: Why Are My Brakes Suddenly Locking Up?

Are you sure it's your brakes and not your wheel bearings? they could be locked up from sitting too long and with no grease in them.Take it for a ride some place and feel your drums. See if they are hot and where. also if they lock up while pulling the trailer disconnect the rubber hose from the master Cylinder and see if that sets the trailer free.

 

[lncoop]

Re: Why Are My Brakes Suddenly Locking Up?

Thanks scoyt. Eagle, it's not the bearings. I'll get it sorted out eventually.

 

[gus-gus]

Re: Why Are My Brakes Suddenly Locking Up?

I have had this happen a couple times. Both times it was me being cheap and buying cheap shoes. The brake compound came loose of the steel part and as soon as the brake application begins the brake material slaps out against the drum and you have uncontrollable brakes. Have a look at the shoes is my suggestion.

 

[04fxdwgi]

Re: Why Are My Brakes Suddenly Locking Up?

A leaking wheel brake cylinder leaking just a little brake fluid on the linings will maker them lock up tight as soon as brakes are applied. But this case sounds more like the master cylinder is still applying pressure on the brakes, due to the surge coupler not releasing fully, or the master is hung up, possibly due to the master being old and getting stuck.

Just rebuilt the Titan 10 on my Eagle trailer (20 years old), because it was barely working and clunking around real bad, due to worn out plastic "bearings" and shocks (dampers) being completely shot. Master worked, but was due to be replaced. The rubber boot on it was all rotted out and the piston rusted real bad, sticking a bit. Tight as a drum now and works smooth as silk. Cost just around one twenty five for all the parts to completely rebuild it and only took a couple of hours. Most of time spent cleaning out old / hard grease, cleaning up the rust and bleeding the brakes.

 

[tswiczko]

Re: Why Are My Brakes Suddenly Locking Up?

The Primary and secondary shoes aren't reversed are they. I done that once and had the same symptoms.

Ran fine for a few miles then would lock up. jacked it up and the wheel spun fine. Put it back down and run a few miles and would lock up again.

I had tore them down and put them back together 3 times before figuring out what I screwed up on the fourth try.:facepalm:

 

[lncoop]

Re: Why Are My Brakes Suddenly Locking Up?

The Primary and secondary shoes aren't reversed are they. I done that once and had the same symptoms.

Ran fine for a few miles then would lock up. jacked it up and the wheel spun fine. Put it back down and run a few miles and would lock up again.

I had tore them down and put them back together 3 times before figuring out what I screwed up on the fourth try.:facepalm:

LOL. That is DEFINITELY something I would do, but that's not it. I've never even removed the backing plates. I replaced the wheel cylinders from under the trailer last year.