Trailer brakes keep engaging when I'm backing it up a slope

[Goffredo]

Hey gang. First post here! I just bought my first boat, a 1999 Cobalt 252, and I'm learning how trailers work (and don't work). The trailer that came with it is a 2005 Sport Boat Trailers Cobalt 252 S25T5, and the tongue has an Atwood coupler -- see attached photo.

I'm having a problem with the coupler's brakes repeatedly engaging when I'm backing it up a slight slope into its parking slot. The process is as follows:

1. Start to back up the slope,
2. "click!" and the trailer brakes lock up.
3. Curse profusely. Pull forward slightly to disengage trailer brakes.
4. On the coupler, slide the little slider along a curve from "TOWING" to "BACK-UP POSITION," and then drop it into the little notch at the very bottom,
5. (Sometimes, the slider will move down but it won't drop into the notch -- so I have to wedge a piece of wood under the trailer tire and drive forward over the wood to "fix" it so it drops into the notch)
6. Get back in the truck. Back up the hill about 2 feet.
7. Click! and the trailer brakes lock up.
8. Go back to step 3

I ended up having to force the little slider to stay in its damned notch with a bungee cord, to be able to park my boat.

Seeing as how my designated boat parking space is on a slope, I'm going to have this battle each and every time I try to park my boat. I sure would appreciate some suggestions on how to fix this, including upgrading the coupler if necessary.

 

[Scott Danforth]

first, welcome aboard

next, do you have drum brakes or disc brakes?

if you have drum brakes and they are properly maintained, they are free-backing

if you have disc brakes, there should be a solenoid on the output of the surge head master cylinder that is shut off when you shift into reverse. this is fed by the blue wire on your 5-pin trailer harness.

so drums or discs?

 

[Maclin]

If you have one just like the one in the pic, then there is a mechanical lockout on it. The curved slot with the bar poking out has a square receptacle on the bottom front. That bar is meant to slide down and follow the curve, then you move it down into that square receptacle. That locks out the braking until it is moved back to the top of the curved path. I had one like that, but it was so old the bar would not stay at the bottom. It was drum brakes though, and I only had a problem when backing up a grassy hill where the trailer did not want to go.

 

[Goffredo]

That bar is meant to slide down and follow the curve, then you move it down into that square receptacle. That locks out the braking until it is moved back to the top of the curved path. I had one like that, but it was so old the bar would not stay at the bottom. It was drum brakes though, and I only had a problem when backing up a grassy hill where the trailer did not want to go.

Yeah this is basically the issue. The knob will move along the curved path and into the little notch at the bottom of its travel, but as soon as I back up a little bit, the knob pops out of the notch on its own accord, and so the trailer brakes lock up again.

 

[Goffredo]

first, welcome aboard

drums or discs?

Thanks! I'm not sure, I'll go out and check and report back. The harness is a flat-4 type, it does not have 5 pins.

 

[Maclin]

It looked like on the one I had, that the knurled part on the knobs had a purpose, and looked like maybe you were supposed to turn it and the one on the other side against each other to hold it there. Mine was so rusty it was useless.

 

[MTboatguy]

Probably need to service the coupler so it works correctly, they take a beating sometimes and need to be serviced regularly to function properly.

 

[Goffredo]

so drums or discs?

Drums!

 

[Goffredo]

the knurled part on the knobs had a purpose, and looked like maybe you were supposed to turn it and the one on the other side against each other to hold it there.

Ah very interesting. I'll give it a try. I thought it was knurled so it was easier to get a hold of, but I have not tried twisting or otherwise futzing with it, once it has fallen into the notch -- only forcing it in place with a bungee.

 

[Scott Danforth]

Pull the drums ans make sure everything is adjusted properly. If the shoes are too loose, they wont free-back

 

[MTboatguy]

Ah very interesting. I'll give it a try. I thought it was knurled so it was easier to get a hold of, but I have not tried twisting or otherwise futzing with it, once it has fallen into the notch -- only forcing it in place with a bungee.

Make sure and spray with a rust breaking product before you try it, that way if it is rusted in the threads it will loosen up and then you can turn it a bit easier, if there is rust in it, you could risk breaking it, or the threads could cross and make it difficult to use.

 

[KD4UPL]

While I agree you need to make sure your drums are adjusted I'd just put the solenoid on it. That's what I recently did. I had the exact same situation you describe. My previous boat trailer had a reverse lock-out solenoid. This one did not. I had a trailer shop install one. The whole job, parts and labor, including the solenoid, was only $70. It's the best money I ever spent.

 

[Horigan]

It sounds like there is corrosion in the brake drum mechanism that is preventing the freebacking feature from working. This could likely affect normal braking operation. I would have the mechanism inspected and any issues addressed. Drum brakes are cheap to maintain.