I tow a boat on a 6000 GVWR tandem trailer with surge activated hydraulic disk brakes. All up, it's probably 5000-5500lbs.

My last set of discs burned up after the brakes STUCK on after I slammed on the brakes hard to avoid an accident. By the time I realized they were dragging, it was too late and the brakes exploded into flame the instant I stopped and they were no longer being cooled by 55mph winds. Pretty spectacular, actually.

It turned out the acutator was pretty badly rusted even though it was only two years old. (I launch in salt water)

Now I've replaced every single brake component on the trailer -- surge actuator, electric lockout, brake lines, connectors, hubs, discs, and calipers.

Yes, I bled the brakes (all 8 caliper cylinders) after I installed everything.

Yes the actuator IS designed for use with disc brakes.

But guess what? The brakes still stick on. Not every time, but intermittently. Enough that I could EASILY burn up another set of hubs

So I'm going over everything AGAIN with a fine toothed comb to figure out why, and I'd appreciate suggestions for things to look for.

If I had it to do again, I might choose different components. But at this point, suggestions to junk a whole trailerful of brand new parts and shell out the big bucks to convert to some other brake technology (the new "immersable" electric brakes, for instance) are not helpful.

-SteveH

 

Salt water is death on any sort of brake system. I'd recommend a fresh water washdown every time you pull the trailer out of the water if you want to keep the brake system alive.

While I was stationed in Hawaii, none of us ran brakes on our fishing boat trailers. Towing a 24' boat and trailer without a braking system *really* gets one's attention...

Lou Braun

 

Two things come to mind here.
1) It seems to me there should be a return spring in your actuator/ coupler mechanism
of about 100 lbs or so that would release any forces on your master cylinder piston unless you were braking and that 100 lbs or so has been overcome.
2) You did not mention whether or not you were using a weight distributing hitch system (spring bars). If you are, this might be putting the surge brake system in a bind and thus not releasing when it should.

 

Thanks for the replies.

Yeah, I've been having fun towing without brakes. I leave lots of room; but I still almost blew it once. In rush hour traffic I slowed down early from highway speed to something less than 15mph when the cars in front of me were backed up, but then I almost didn't allow enough space to burn off that last 15mph, and ended up locking up the front wheels on the truck and stopping uncomfortably close to the car in front.

I recognize the need for regular washdowns, but with all the parts on the trailer brand new, and the problem recurring before the trailer ever saw the water, something else is up with either the parts, the installation, or both.

Yes, the master cylinder piston on the actuator has a return spring. But the actuator seems to stick for some reason (sometimes) with about a quarter or half an inch of travel left to go. My next stop is replacing the actuator *again.* (The trailer vendor is shipping me a new one from a different vendor this time, gratis.)

It's a good thought about checking for a weight distributing hitch overloading the stated tongue weight of the surge actuator; but I'm not using a weight distributing hitch.

 

Is the trailer perfectly level when it's hooked up? If not, the actuator could be in a slight bind after braking and not releasing completely. This needs to be checked with the boat AND tow vehicle loaded like they would be for a trip, including passengers. Just a thought.............

 

What if they are not going on all the way? maybe an air pocket. It has been my experience with that terrible system that they stick until they clunk out when you accelerate. If they were not all the way on in the first place, you may not be able to pull hard enough to get it off. Have you tried accelerating hard? Are you underpowered or overloaded?