MFI Trailer Issue

[Captbob]

The trailer brakes have started going on in reverse on any small incline. There is electricity getting to the reverse solenoid. I used a test light. It was always very sensitive in reverse but has gotten worse. Anyone have any advice?

 

[Bruce]

How is your ground? Perhaps there is power but not enough to disengage the brakes?

 

[Captbob]

I'll check the ground.

 

[Big Shasta]

Might just be a faulty solenoid. If all the wiring checks out, Have someone put it in reverse while you listen to it. You should be able to hear it click. They aren't that expensive, should be under 50.00.

 

[Ronnie]

My trailer locked up, as expected when I backed up a small incline before backing down a ramp yesterday. I will test it like @Big Shasta suggested but if I don't get around to replacing or fixing it soon I will just use the "D" key, a nickel or something to mechanically block the surge brakes from activating.

 

[Captbob]

I cleaned the ground real well and the switch does not make a clicking noise so it must be a bad reverse solenoid. It looks like a knuckle buster. Has anyone have any ticks to the easiest way to replace it?

 

[Ronnie]

It's not bad, you can get the part online. Fold the tongue, unscrew the brake line, remove the c clips that hold the assembly in the sleeve of the tongue, pull the assembly out and work on it from there, preferably on a bench. You may need to bleed the brakes afterwards, not sure, I just replaced the safety cable not the solenoid.

 

[David D]

There's got to be a way to avoid this like electrically, like the guys above said, if you have electric brakes. But I think what is happening is that you have a hydraulic breaking system that activates when the trailer shifts forward on the ball. That happens whenever you back up. My trailer has a metal "thingy" (a technical term) that you can insert into the hitch mechanism to disable that forward movement. I'm not home or I'd send pictures. ----- I just saw you have a 24ft boat, so maybe you don't have hydraulic momentum brakes??

 

[Captbob]

They are disc surge brakes. I just ordered the part. Should be here Wednesday.
Thanks also Ronnie. I hope it is as easy as you say.

 

[Ronnie]

Easy is a relative term. Getting the c clips off was easy, getting them back on, not so much. The stock or magnetic d key as well as a nickel and some tape are easy to use, the down side being you have to remember to remove the items before you trailer your boat.

When I experimed the problem yesterday I just continued to back up the ramp with the brakes locked up, left little black skid marks (two three foot sections) but it was a lot easier than reseting the trailer and installing a mechanical block.

 

[Captbob]

Ronnie , Do you remember whether you removed the front 2 rings only or all 4?

 

[Ronnie]

All 4. It's the only way to get the assembly out of the outer sleeve. Here is a link to my post on the subject which includes some pics I took but remember I was just replacing the safety cable not the solenoid itself. There is also a link to a web page which contains some animation showing how surge brakes work. See my post of 9/11/14 at 11:14 am.

http://yamahajetboaters.com/forum/viewtopic.php?f=1&t=63775&hilit= Surge brake

 

[Ronnie]

@Captbob , correction, you only need to remove two of the c clips one on each rod. It does not matter which side or if you switch sides. This will allow you to push the retention rods out and the Internal assembly should drop out. Don't forget to move the trailer wirkng out of the way first, you will need to remove the brake line from the main cylinder to colete separate the internal tongue assembly from the trailer.

I don't know what the cost of the main cylinder is but is may be easier to just replace the whole assembly.

 

[Captbob]

The solenoid is a separate unit. I took a picture of it to the dealer so he could order the right one. I may try and squeeze it out. I may be lucky or may be not, but again Ronnie thanks very much for the advice.

 

[Matt Phillips]

I carry a C-clamp in my trailer box for moments like those. just expand the tongue, spin the c clamp on it and it'll back up hill if needed. just don't forget to remove said clamp or you won't have any trailer brakes.

 

[Ronnie]

Yes a nickel and tape will work in a pinch, just need something to mechanically block the surge brake mechanism from operating/compressing. There is another option, a cap that replaced rhe outer surge brake fluid cap which you could turn to mechanically block the surge brake from compressing and which would automatically disengage when the tow vehicle moves forward. However, for what we pay for these boats and trailers and how seldom they get used it is reasonable to expect that they will work as designed.


The newer mfi trailers should automatically disable the surge brakes when the tow vehicle is put In reverse. The older ones had a bare blue lead that the user had to connect whenever backing up a hill the problem with it is that you had to remember to disconnect it because it was an always on configuration when it was plugged in (I.e., as long as it was plugged in the surge brake was disabled).

 

[Captbob]

One broken tool, one stripped bleeder valve, and a large cut above the eye and 3 hours and 40 minutes later I'm done. Ronnie was right about the clips being a bitch. The ring tool broke off as I was putting the last clip on. The worst part was removing the brake line hose at the solenoid. It is a solid piece but flexible line. The line does not want to twist. It has to come off before you remove the actuator and the last item to go back on. I had to twist it with a wrench while holding it with a pair of pliers. The MFI trailer is one of the hardiest trailers I have ever worked on. I have had one Shorelander, one EZ Loader, and 2 Loadrites.

 

[tdonoughue]

AAANNNDD? After all of that, did it work?!?!

One likes to see progress, especially if there was blood involved.

 

[Ronnie]

I'd bet @Captbob got it done and done right.

Now we have something in common, losing money by repairing it ourselves. I think it took me more than 3.5 hours to repair mine. In retrospect it would have been cheaper and easier for me to replace the entire surge brake assembly for $130 ish instead of just the safety cable for under $10.

 

[Captbob]

The answer to the question does it work now is YES. You can hear a distinct clicking sound when the reverse is activated. I also backed it up an incline with no problem. The worst part was still the removal of the brake line. It is a poor design. The wound occurred when the socket I was using to remove the frozen bleeder valve flew back and hit me above the eye. I stopped the blood from flowing into my eye with a small dap of anti-seize. I wasn't about to get out from under the trailer when I was 95% done. I also got a small magnet from Home Depot to hold the lock out key on the trailer in case it is needed.